Y

\'?'t\'<{"[

A RETROSPECTIVE

CEPHALOMETRIC STUDY OF THE

EFFECT oF THE rnÄNrnt-, APPLTANcE,

THE CLARI( T\MIN BLOCK AND THE ACTIVATOR ON

CLASS II DIVISION 1 PATIENTS

***l*

A Thesis Submitted in Partial Fulfilment

for the Degree of Master of Dental Surgery

by

Con Laparidis

Dental School Faculty of Health Sciences University Of Adelaide

South Australia

1999 Tnsre or CoNrexts 2

TABLE OF CONTENTS

TABLE OF CONTENTS 2

List of Tables...... 5

List of Figures ...... 9

Summary T3

I AIMS t6

2. LITERATURE REVIEV/...... t7

2. 1 Introduction...... t7 2.2 Summary of adolescent growth changes 18

2.3 Comparison between "normals" and Class II patterns '. 26 2.4 Functional appliance effects.... 27 2.5 Conclusion...... 68

3. MATERIALS AND METHODS .... 69 3.1 Selection of sample...... 69 3.2 Radiography 72 3.3 Tracing technique 74 3.4 Superimposition technique...... 75 3.5 Computerised cephalometrics and digitising 78

3.6 Reference points. 79 3.7 Thevariables 82 3.8 Statistical analyses...... 84 3.9 Errors of the method...... 87

4. RESULTS 90 4.1 The error study 90

4.2 Pre-freatment ages and treatment times...... 96

4.3 Sex comparisons of pre-treatment hard and soft tissue variables ...... 97

4.4 Sex comparisons of post-treatnent hard and soft tissue variables...... 104 4.5 Hard and soft tissue treatment changes for the activator, the Clark Twin Block and the Fråinkel .... TABLE OF CONTENTS J

4.6 Sex comparisons in treatrnent changes..... '..'.. 118 4.7 Comparison of different appliances: two'way analysis of variance .. 118 4.8 Comparison of different applainces: one-way analysis of variance ...12t 4.9 Comparison to published controls..... 125 4.10 Pre- and post-treatment composite tracings 126

5. 131 5.1 The sample 131 5.2 Age of patients ...... 131 5.3 Treatment time ...... t32 5.4 Limitationsofretrospectivecephalometricstudies ...... '....133 5.5 Erors in cephalometrics...... r39 5.6 Sexual dimorphism..... r42 5.1 The activator with headgear 142 5.8 The Clark Twin Block 151 5.9 The Fråinkel r59 5.10 Comparison of the results from the present study with published

untreated subjects ...... 165 5.11 A comparison of the activator with headgear, the Clark Twin Block,

and the Fråinkel ...... 172

5.12 Compa¡ison of skeletal and dental changes contributing to overjet and

molar correction. ..

6. CONCLUSIONS...... 182 6.I Futr¡re resea¡ch. 185

7. REFERENCES : Literature cited.. 187

8. APPENDICES 8.1 Landmarks 2r2 8.2 Calculation of angular and linear variables. 2t6 8.3 Correlations and coeffrcients of determination 224 8.4 Cranial base superimposition- treatment changes for landmarks using Taslg or CoNreNrs 4

SN-7o Cartesian rxes...... 229 8.5 Summary of signifrcant differences between males and females pre-

and post-treatrnent ...... 238

8.6 Comparison with untreated subjects 240 8.7 Individual treatnent changes for selected variables... 258 Teerp or CoNrBNrs 5

LIST OF TABLES

Table 1 Attainment of adult size for various soft tissue variables and three skeletal base measurements (Nanda et a1.,1990)...... 23

Table2 Sexual dimorphism in adolescence ...... 25

Table 3 Advantages of the Cla¡k Twin Block ...... 58

Table 4 Breakdown of the functional appliance sample numbers and ages...... 71

Table 5 Cephalometric radiographs with visible metric rulers ...... 72

Table 6 Facilities from which cephalometric radiographs were obtained 73

TableT Mean magnifications of cephalometric radiographs ...... 74

Table 8 Hard tissue cephalometric landmarks and abbreviations 81

Table 9 Soft tissue cephalometric landmarks and abbreviations 82

Table 10 Hard tissue cephalometric variables and abbreviations...... 83

Table 11 Soft tissue cephalometric va¡iables and abbreviations ...... 84

Table 12 Error Study : Results for double determinations of landmark identification. Hard Tissue Landmarks 9T

Table 13 Enor Study : Results for double determinations of landmark identifi cation. Soft tissue landma¡ks. 93

Table 14 Error Study : Results of double determinations for va¡iables. Hard tissue variables 94

Table 15 Enor Study : Results of double determinations for variables. Soft tissue variables 95

Table 16 Tables of pre-treatment age (in years) and length of treatment (in days) 96

Table 17 Activator : Sex comparisons of pre-treatment hard tissue variables.... 98

Table l8 Activator : Sex comparisons of pre-treatment soft tissue variables..... 99

Table 19 Cla¡k Twin Block : Sex comparisons of pre-treatment hard tissue variables 100

Table 20 Clark Twin Block : Sex comparisons of pre-treatment soft tissue variables.... 101

Table2l Fråinkel : Sex comparisons of pre-treatment hard tissue variables...... 102

Table 22 Frânkel : Sex comparisons of pre-treatrnent soft tissue variables... 103 TABLE OF CoNTENTS 6

Table 23 Activator : Sex comparisons of post-treatment hard tissue variables . ...105

Table 24 Activator : Sex comparisons of post-treatment soft tissue variables.. ...106

TabLe 25 Clark Twin Block : Sex comparisons of post-treatment hard tissue variables ...t07

Table 26 Clark Twin Block : Sex comparisons of post-treatment soft tissue variables 108

Table 27 Fränkel : Sex comparisons of post-treatment hard tissue variables 109

Table 28 Fränkel : Sex comparisons of post-treatment soft tissue variables 1r0

Table 29 Activator : Means and standard deviations for treafinent changes. Hard tissues tt2

Table 30 Activator : Means and standard deviations for treatment changes. Soft tissue variables lr3

Table 31 CTB : Means and standard deviations for treatment changes. Hard tissues...... tt4

Table 32 CTB: Means and standard deviations for treatment changes. Soft tissue variables 115

Table 33 Fråinkel : Means and standard deviations for treatment changes Hard tissues...... tt6

Table 34 Fråinkel : Means and standard deviations for treatment changes. Soft tissue variables r17

Table 35 Comparison of the changes in craniofacial and soft tissue variables from pre-to post-treatment between males and females 118

Table 36 Two-way analysis of variance, with functional appliance groups and sexes as factors. Hard tissue variables. .. 119

Table 37 Two-way analysis of variance, between functional appliance groups and gender. Soft tissue variables...... 120

Table 38 Pre-treatment one-way analysis of variance comparisons ...... r22

Table 39 Po st-treatment one-way analysis of variance comparisons...... 123

Table 40 Pre- to post-treatment differences: one-way analysis of variance ...... t24

Table 41 Summary of statistically significant differences between the three fimctional appliance groups .184

Table 42 Significant correlations between age and craniofacial / soft tissue variables.. 224

Table 43 Significant correlations between treatment time and craniofacial / soft tissue variables. 226 Teel,e or CoureNrs 7

Table 44 Craníal Base Superimposition: treatment changes for activator / headgear ha¡d tissue landmarks. 229

Table 45 Cranial Base Superimposition: treatment changes for activator / headgear soft tissue landmarks. 23t

Table 46 Cranal Base Superimposition: treatment changes for the Clark Twin Block hard tissue landmarks. ..232

Table 47 Cranal Base Superimposition: treatment changes for the Clark Twin Block soft tissue landmarks. 234

Table 48 Cranial Base Superimposition: treatment changes for the Fränkel hard tissue landmarks. 235

Table 49 CrantalBase Superimposition: treatment changes for the FrZinkel soft tissue landma¡ks. ..237

Table 50 Significant differences between males and females pre-treatment...... 238

Table 51 Significant differences between males and females post-treatment. . ..239

Table 52 Age comparison of the three functional appliance grouPs with the Illing et al. (1998) and Monis et al. (1998) control group. 240

Table 53 Control comparison with the pre-treatment male activator group ...... 241

Table 54 Control comparison with the pre-treatment female activator group... .242

Table 55 Control comparison with the pre-treatment male Clark Twin Block group. ..243

Table 56 Control comparison with the pre-treatment female Clark Twin Block group...... 244

Table 57 Control comparison with the pre-treatment male Fränkel group...... 245

Table 58 Control comparison with the pre-treatrnent female Fråinkel group...... 246

Table 59 Control comparison with the post-treatment male activator group.... .247

Table 60 Control comparison with the post-treatment female activator group ...248

Table 61 Control comparison with the post-treatment male Clark Twin Block group...... 249

Table 62 Control comparison with the post-treatment female Cla¡k Twin Block group. ...250

Table 63 Control comparison with the post-treatrnent male Fråinkel group ...... 251

Table 64 Control comparison with the post-treatrnent female Fränkel group...... 252

Table 65 Lange et al. (1995) control comparison wittr the post-treatment activator group ...253 T¡,erp OF CONTENTS 8

Table 66 Lange et al. (1995) control with the ctlrent post- treatrnent Clark Twin Block 2s5

Table 67 Lange et al. (1 995) control comparison with the post-treatment Fråinkel group 257 TABLE OF CONTENTS 9

LIST OF FIGURES

Figure I Expected changes ofthe nasal dorsum 2l

Figure 2 The total increments of size increases for males and females aged 7 to l8 years...... 26

Figure 3 The effect of the latera] pterygoid muscle...... 34

Figr:re 4 Control mechanisms of condylar cartilage gro'rth rate in rats...... 37

Figure 5 Bone adaptation due to mechanoreception and mechanotransduction. .. 43

Figure 6 Bone adaptation due to threshold exceeding stimulus....'.... 44

Figwe 7 Gradual structural changes due to ñnctional appliances...'. 46

Figr.ue 8 Activator with headgear tubes (used in the present study)- frontal vle\il 48

Figwe 9 Activator with headgear tubes (used in the present study)- side vlew 48

Figure 10 Centre of resistance in the mærilla...... 50

Figure 11 Clark Twin Block (as used in the present study)- Occlusal view... 54

Figure 12 ClarkTwin Block (as used in the present study)- side view.. 54

Figure 13 The sequence of trimming the upper molar covering to reduce overbite. ..56

Figure 14 The pterygoid response ..57

Figure l5 Fråinkel - frontal view.. ..6l

Figure 16 Fråinkel - side view 61

Figure 17 Structures suggested by Bj örk and Skieller (1983) for cranial base superimposition...... , 76

Figure 18 The cephalometric landmarks...... 80

Figure 19 Activator / Headgear Composite Tracing: Males t27

Figure 20 Activator / Headgear Composite Tracing: Females...... t27

Figwe 21 Clark Twin Block Composite Tracing: Males...... 128

Figure 22 ClarkTwin Block Composite Tracing: Females ..128 Tesln on CoNrBNts 10

Figure 23 Fränkel Composite Tracing: Males..', ..r29

Fignre 24Frrärltkel Composite Tracing: Females ..t29

Figure 25 Comparison of skeletal and dental horizontal changes contributing to overjet correction. ... 178

Figure 26 Comparison of skeletal and dental horizontal changes contributing to molar correction...... 180

Figure 27 Graphs displaying the individual changes, for selected variables obsêrved iñ the three functional appliance groups' 258 AcrNowLEDGEMENTS 11

ACKNOWLEDGEMENTS

I wish to extend my underlying appreciation and gratitude to the following, for without them, this compilation would not have been possible.

The Australian Society of Orthodontists. 'Wayne professor J. Sampson, P.R.Begg Chair in Orthodontics, University of Adelaide, who not only provided cherished words of wisdom, but a learning bank of unparalleled riches. V/ithout his tireless efforts and encouragement I would have " attempted little and achieved even less". professor Grant C. Townsend, Dental School, University of Adelaide, for his unrelenting precision in guidance and direction.

I am also indebted to Mrs. V/endy Schwerdt for the production of copious volumes of SpSSX statistics, which were indispensible in the analysis of the data. Toby Hughes and Phil Leppard are also acknowledged for their advice.

Dr. Colin Twelftree, Dr. Guy Burnett and Dr. Steve Bajada, orthodontic practitioners and part-time orthodontic tutors, University of Adelaide, whose high quality data provided me with the foundation for this thesis. I am greatly appreciative for their kindness in allowing me to freely access their patient records. Without them this thesis would not have been possible.

To my parents, George and Sophia, for their unconditional love and encouragement in every endeavour I have undertaken. To my parents-in-law, Mr. Bartholemew and Mrs. Mary Velis, for their inexhaustible patience, generosity, continual support and guidance,

freely given at" any time of need.

I dedicate this thesis to my family who have been a constant source of inspiration. To my beloved wife Sandra and daughter Sophia, who I adote, for their endless support, innumerable sacrifices, love and patience. Above all for my two year old Sophia, who often sat upon my knee during the compilation of this thesis for giving me reason to reach for the stars.

SuvtueRY

SUMMARY

of the The complete evaluation of facial balance and harmony includes an examination chin are facial profile. The relationship and balance between the size of the nose, lips and that soft essential for a balanced facial appealance. In the past, Angle (1907) believed is tissues automatically adopt a harmonious relationship once a "no1mal" occlusion related to the established .ln 1957 Riedel stated that the soft tissue profile was closely skeletal and dental structures. This, however, may not be the case. In 1959 Subtelny it confirmed that the bony and soft tissue profiles matured along opposing paths, and could not be assumed that the soft tissue profile was similar to the underlying skeletal profile. Burstone (1958) and Neger (1959) stated the variation of the actual soft tissue thickness may influence the differences between the hard and soft tissue profile.

Functional appliances are mainly used to correct "retrognathic mandibles" in skeletal Class II patients. Functional appliances transmit, eliminate or guide natural forces of growth, muscle function and tooth eruption. Typical treatment time is twelve to eighteen months. They may act by redirection of growth and changing its timing (Fields, l9g3) and it is controversial whether they produce changes in absolute size' Nevertheless, the overlying soft tissues are affected'

A review of the literature suggests a lack of published data on the effects of functional appliances on the soft tissue profile.

The present research involved an observational retrospective study to determine if any differences exist in the soft tissue profile of Class II division 1 patients before and after treatment with three different functional appliances; the activator with headgear, the Clark Twin Block, and the Fränkel.

The aim of this thesis was to test the null hypothesis, that the soft tissue profile response is independent of the type of functional appliance used in the correction of Class II division 1 patients. SUMMARY 14

The criteria for sample selection included

1. Angle Class II, division 1 maloccluston.

2. At least one Class II molar relationship. 3. A minimum overjet of 4mm 4. No prior serial extractions, nor any concurrent orthodontic treatment during the course of functional theraPY'

5. The absence of observable major dental and craniofacial deformity. 6. Pretreatment radiographs taken within 90 days before the start of active treatment. End of treatment radiographs taken within 90 days after discontinuation of functional therapy, or the radiograph was taken and treatment continued for a varying length of time, prior to the retention period.

7 . All individuals were of Caucasian origin'

The three individual functional appliance samples were obtained from three private practices. No attempt was made to determine success of the treatment response in case selection.

The sample consisted of 94 Class II division 1 patients. Thirty-five consecutive patients (17 males and 18 females) were allocated to the activator group, thirty patients (17 males and 13 females) to the Clark Twin Block group, and twenty-nine patients (15 males and 14 females) to the Fränkel group

The mean ages of the Fränkel (10.8 years), the activator with headgear (11.1 years) and the Clark Twin Block (10.6 years) were similar, with a range of 8.0 to 14.7 years. Mean treatment times varied between the groups, activators with headgear being used for an average of 610 days, Fränkels for 596 days, while Clark Twin Blocks were worn for 465 days. Differences in age, sex and treatment time were considered.

Soft tissue analysis was performed and compared to the dento-skeletal structures on cephalometric radiographs which were adjusted for magnification prior to the analysis. Error statistics were determined and evaluated in an effort to validate reliability' Statistical comparison of data was executed to determine if sexual dimorphism was SulvttuaRY 15

present and to determine if the soft tissue profile was independent of the type of functional appliance used. In addition, a comparison with appropriate untreated controls was made, so as to determine the effect of functional appliance treatment'

Some differences were discovered between males and females pre-treatment, especially in the Fränkel group. The overjet in the Fränkel group, was 8.2mm in the males and 6.2mm in the females. Post-treatment, more variables were significantly different between males and females, especially in the Clark Twin Block group. The significant overjet difference in the Fränkel group was no longer evident'

The SNA angle decreased in females of the Clark Twin Block group. The SNB increased in all groups, thus effectively decreasing the ANB angle. The application of the activator with headgear appeared to limit the anterior displacement of the maxilla, yet the maxillary complex continued to descend vertically.

Upper incisors uprighted with treatment in all three groups. Lower incisors proclined in the Clark Twin Block and Fränkel groups. All groups showed statistically significant decreases in overjet and overbite. The biggest overjet decrease was seen in the Clark Twin Block group. The least overbite decrease was detected in the activator with headgear group. The Frankfort-mandibular plane angle did not change significantly during treatment in any of the appliance groups.

Facial convexity decreased most in the Clark Twin Block group, then the Fränkel group and then the activator with headgear. The nasolabial angle changed similar amounts between the groups, yet the labiomental fold decreased most in the Fränkel group. The soft tissue changes appeared to be correlated to some extent with the underlying hard tissues however a wide variation in response was evident. The null hypothesis that the soft tissue prohle change is independent of the type of functional appliance used in correction of the Class II division 1 patient was rejected.

Long-term evaluation is necessary to determine the stability of the treatment effects. This has been recommended for future research' Altrrts 16

1. AIMS

The broad aims of this research project were to determine the effects of three different functional appliances, the activator, the Clark Twin Block, and the Fränkel appliance, on a selected longitudinal sample of patients with Class II division 1 malocclusions.

The specific aims of this study were:

1. To provide a comprehensive and critical literature review with respect to the use of these three functional appliances in actively growing patients and the effects observed.

Z. To establish suitable, unbiased matched sample of Class II, division I subjects to enable comparison between the treatment effects of three types of functional appliances in routine clinical application. 3. To investigate changes which may have occurred dwing the course of the treatment.

4. To investigate changes in soft tissue profile which may have occurred in the couïse of functional appliance therapy.

5. To compare the treatment results with past research and other published works. 6. To determine if there were differences between males and females pre-treatment and post-treatment in craniofacial and soft tissue variables. of the type 7 . To test the null hypothesis, that the soft tissue profile is independent of functional appliance used in the correction of Class II division 1 patients. LITERATURE REVIEW tl

2. LITERATURE REVIEW

2.1 INTRODUCTION

Facial appearance is a compelling motive for individuals to seek orthodontic treatment (Riolo et aL, LgBl). Despite the plethora of publications on the mode of action and the treatment effects of functional appliances (McNamata et a1.,1975,1979,1987) there is a disappointing lack of information on effects on patients' soft tissues (Subtelny, 7959; Forsberg and Odenrick, 1981;Nanda et al., 1990; Bishara etal., 1997 Nanda, 1998). This insufficiency may be due to the imprecise stability and reproducibility of a relaxed lip position on cephalometric measurements (Hillesund et al., 1978).In addition, until recently, profile assessment was limited to a two-dimensional assessment of a three- dimensional change measured from a cephalogram (Subtelny, 1959; Bishara et al',

1 e8s).

Optimal facial harmony is required in our patients. Angle (1907) initially stressed the importance of the soft tissue profile. Soft tissues were later recognised as being important in treatment planning (Riedel, 1957; Ricketts, 1957; Neger, 1959)' Stoner et al. (1956) in addition to Huggins and McBride (1975) believed treatment could help change facial appearance and improve the soft tissue profile. Angle (1907) postulated that the placement of teeth in their correct position would automatically allow a harmonious draping of the perfect prof,rle. However, a single type of skeletal and dental pattern may be associated with a variable arrangement of integumental profiles (Burstone, 1958).

Functional appliances are most often employed to assist in correction of Class II malocclusion in patients. Functional appliances transmit, eliminate or guide natural forces of growth, muscle forces and tooth eruption. Direct force application onto the teeth is possibly also involved. LTTERRTURE REVIEV/ 18

eI Very few studies are dedicated to soft tissue analysis (Bishara et al., 1985; Nanda al, nose and 1990). Prahl-Andersen and co-workers (1995) studied the growth of the lips, chin in a mixed longitudinal sample aged between nine and fourteen years. They linear. determined that the correlation between the hard and soft tissues was not strictly The soft tissue growth was quite independent of the underlying hard tissues. Soft tissues varied in thickness over the different parts of the craniofacial skeleton (Prahl-Andersen et al., 1995). Thus the correlation with the soft tissue prof,rle is not predictable (Lundström et al., lgg2). The assumption can not be made that correction of the underlying hard tissues will automatically allow the soft tissues to harmoniously drape over them (Burstone, 1958)'

2,2 SUMMARY OF ADOLESCENT GROWTH CHANGES

Buffon in 1749 was probably the first to clearly describe the adolescent growth spurt (Tanner, 1987). Normal pubertal growth occurs when there is adequate nutrition and tþroid function. Puberty in males is probably caused by stimulation of the hypothalamus, which in turn stimulates luteinizing hormone secretion from the anterior pituitary (George, 1,987). In females however, anterior pituitary follicle stimulating hormone secretion is secondary to the hypothalamus stimulation, with follicle- stimulating hormone leading to follicular development in the ovary and accompanying estradiol production (George, 1987). The gonadal hormone secretions interact with the actions of the pituitary to affect the rate of craniofacial bone development and maturation (George, lg87). Björk (1963, 1966) reported a pattern of craniofacial growth in humans which was similar to that for stature. Hägg and co-workers (1987) also determined the close relationship between the pubertal peaks of facial growth and height. Other investigators (Tofani, lg72), found a low correlation in growth velocity of pubertal height and facial dimensions. In 1987 Luder confirmed the close relationship between craniofacial growth and overall somatic growth. LITERATURE REVIEW 19

2.2.1 HARD TISSUES

The immature convex profile of a child tends to become less convex with growth' The maxilla appears progressively less protrusive relative to the rest of the facial profile. This is due to the accelerated mandibular growth relative to the maxilla during adolescence.

With growth, the ramus remodels posteriorly and this allows backward growth of the mandibular alveolus and lengthening of the corpus (Fränkel and Fränkel, 1989; Enlow and Hans, 1996). Thus this previous part of the ramus now becomes the corpus, allowing it to become lengthened. The corpus length and ramus height grow in a rather irregular pattern (Dibbets et al., 1987)'

Ramus "uprighting" occurs as the angle of the mandible changes so as to accommodate the growing pharynx (Moss and Salentijn, 1969). It provides the ability to retain the coordination of the upper and lower dental arches, and thus maintain facial balance'

Facial balance is dependent on the equivalent quantum of the vertical nasomaxillary growth and vertical growth changes associated with the mandibular arch, the ramus, and the middle cranial fossa. Any mismatch of these will produce a mandibular rotation.

Björk and Skieller's (1983) implant studies were able to determine the components of mandibular rotation. These act independently, yet are coordinated. Growth of a particular area requires, coordinated growth andlor remodelling, via periosteal resorption and deposition, so as to maintain the complex shape and proportions evident (Enlow, l9l5; Björk and Skieller, 1983).

The chin shows considerable variation, both in size and shape. It is one of the most variable growth areas of the mandible and slowly continues to enlarge with age. It progressively moves farther forward in relation to the upper face (Subtelny, 1959). The most typical combination of remodeling is with deposition of bone at the apex of the chin. Cortical regression moves the alveolus posteriorly while the chin continues to grow with apposition at pogonion (Enlow, 1968). This progressively enlarges the chin and changes its contour. There is marked variation in the amount of deposition and resorption (Enlow and Hans, 1996). LITERATURE REVIEW 20

2.2.2 SOFT r/^SSUES

tissue growth' Orthodontists tend to be more informed on skeletal growth than soft The relying often on hard tissue analysis for orthodontic treatment (Yogosawa, 1990)' Not all correlation between hard and soft tissues is not strictly linear (Subtelny, 1959). (Burstone' 1958; parts of the soft tissue profile follow the underlying skeletal structures Sforza, Miani et Genecov et a1.,1990; Nanda et a1., 1990; Formby et al., 1994; Ferrario, aL.,1997).

Growth and development, including that of the lips, cheeks, tongue and periodontium of the teeth. can disturb the equilibrium and have a marked influence on the position (Riolo There is also a need to correlate the local soft tissue changes with weight change gain et al., 1987). The thickness of the chin has been seen to change in adults as they profile reacts in and lose weight, but there is no evidence that the remaining soft tissue the same manner (Riolo et al., 1987). Body composition and changes in composition may be 'effect modifiers' of the soft tissue profile. Fat children, have thicker soft tissue profiles. Early maturing subjects appear to also have greater soft tissue thickness at most ages, this being more evident in males (Riolo et al,, 1987).

Opposite to what we may expect, long-faced individuals experience their pubertal growth spurt earlier and exhibit thicker and longer soft tissue drape than short-faced vertical patterns (Blanchette eL al., 1996). This may be a compensatory mechanism to mask the vertical discrepancy and to "normalise" the facial profile (Blanchette et al., t9e6).

The direction of growth of the nose apparently closely approximates the nasal bone (Subtelny, 1959; Posen, 1967; Prahl-Andersen et al., 1995) and the "hump" occuls during the adolescent growth spurt (Subtelny, 1959; Posen, 1967; Ferrario, Sforza, Poggio et al., 1997)"

Growth of the dorsum of the nose is regular and linear, with the majority of growth being complete by 16 years (Posen,1967). Nasal growth however continues throughout life (Behrents, 1997). Shape changes associated with the nasal dorsum are closely related to the changes of the lower dorsum. Even though the upper dorsum rotates up and forward approximately 10o between the ages of 6 to 14 years, the major contribution is from the lower dorsum. This upward rotation is relatively greater in girls (prahl-Andersen et al., 1995). The lower dorsum may rotate up and forward in horizontal growers, or down and back in cases where there is limited horizontal growth of the maxilla and excessive vertical growth (Buschang et al., 1993). This is however dependant on the method of superimposition' LTTnRETURE REVIEW 2l

Figure 1 Expected changes ofthe nasal dorsum

a)"Expected changes of nasal dorsum in some Glass llcases with more limited ' hoiizontal groralth of maxilla together with excessive vertical growth." ( from Buschang et al. 1993 )

I I

I I rl\\ -ì. a, \,\

\ I

I I

I

b)"Expected changes of nasal dorsum in excessive anterior maxillary growth."

I I

I I

I I LITERATURE REVIEW 22

Class II subjects have a marked elevation of the dorsum, whereas Class I subjects have more forward growth at the nasal tip (Chaconas, 1969). This elevation of the dorsum may be associated with the limited forward growth of the nose tip with respect to the nasal bone (Posen, 1967). The sagittal growth of the nose is independent of the underlying skeleton (Posen, L967; Nanda et a1., 1990; Prahl-Andersen et al., 1995; Ferrario, Sforza, Poggio et al., l99l).In addition, the female lower nose attains adult height by 15 years whereas the male continues to show growth even at the age of 18 years. Thus total facial convexity increases with age (Bishara et al., 1985)' Holdaway's angle decreases with age (Bishara et aL,1985). The inclination however, of the nasal base and the nasolabial angle changes little after 7 years of age (Bishara et al., 1985). Nanda et al. (1990) noted a decrease in the nasolabial angle in both sexes during adolescence, even though there is retrusion of the lips with time. This is primarily due to the fact that nasal prominence relative to the rest of the soft tissue profile increases with growth (Bishara et a1.,1935). This produces an increase in the total facial convexity in both males and females (Subtelny,1959; Bishara et al., 1985).

Burstone (1967) stated the average lip length to be 24mm in males and 20mm in females, with an upper lip to lower lip ratio of I to 2.

The upper lip usually overlaps 6l%-61% of the upper central incisor crown, with the remainder being covered by the lower lip (Subtelny, 1959). The growth of the lips follows the growth of the muscles and other connective tissues (Scammon et a1., 1930).

Vig and Cohen (1979) noted most of the lower lip increase was detected between 10 to 11 years and 13 to 18 years in males and 11 to 13 years of age in females. Males demonstrate a more protrusive upper lip, while the lower lip, relative to the nose and chin, becomes more retrusive with age in both sexes (Bishara et al,, 1985).

In general, the vermillion regions closely follow the contour of the underlying hard tissues (Subtelny, 1959).

The soft tissue chin inclination is seen to be approximately the same in both sexes, whereas males show greater inclination of the hard tissue chin (l{anda et a1.,1990). LITERATURE REVIEW 23

Table I Attainment of adult size for various soft tissue variables and three skeletal base measurements (Nanda et al., 1990).

continuing at variable % of growth comPlete Growth ending by 15Yrs Growth complete 15 to Growth by 7 years 18yrs l Syrs

Male Female Male Female Male Female Male Female

Upper 80% 82% Yes Yes nose complete height

Lower 67% 90% Yes Yes Nose complete Height

Nose 63% 70% Yes Yes Depth complete

Nose 85% 90% Yes Yes Skeletal complete Base ;at prn'-PMV

Upper 87% 90% Yes Yes Nose complete lnclination

Lower 92% 89% Yes Yes Nose complete lnclination

Upper Lip 88% 95o/o Yes Yes Length complete

Lower Lip 78% 91% Yes Yes Length complete

Upper Lip 73% 76% Yes Yes Thickness complete atA

Upper Lip 82% 93o/o Yes Yes Thickness complete at LS

Lower Lip 85% 89% Yes Yes Thickness complete at Ll

Lower Lip 80% 85% Yes Yes Thickness complete at "8"

Chin 83% 88o/o Yes Yes Thickness complete at Pog

lnclination 44% 27% Yes Yes of complete Skeletal Chin

lnclination 72% 66% Yes yes of Soft complete Tissue Chin LITERATURE REVIEV/ 24

2.2.3 BOYS VERSUS GIRLS

In general, males continue soft tissue growth until past 17 years of age whereas females conclude alarge proportion by the age of 12 years (Genecov et al', 1990)'

The male profile straightens with age. Both lips become more retrusive relative to the E- line as the nose and chin increase in size. Small incremental increases continue throughout life (Genecov et a1., 1990; Behrents, 1997). Over time a decrease occurs in upper and lower lip thickness.

The female profile does not become as straightened with age as the male profrle. The female lips are less retrusive and even though the nose increases in size, it is not to the same extent as the male. In females the upper lip tends to decrease in thickness and the lower lip tends to increase. Lip thickness appears to be stable after 14 years of age in females whereas growth continues in males. After 9 years of age the vertical growth of the lips and the alveolar process is approximately equivalent, such that the lip line remains constant in relation to the central incisors. LITBRRTURE REVIEW 25

Table 2 Sexual Dimorphism in Adolescence

Compilation from Riolo et al. (1987); Enlow and Hans (1996)' FEMALES MALES

Age of the Growth SPurt 10-12 years 12-14 years

Size Growth until 14 years old Until 18 years old Moderate increase until 16

Supraorbital Ridges Not evident Well developed

Frontal Sinus Small Large

Nose Moderate Large

Cheekbones Small Large

Mandibular Symphysis Round Prominent

Gonion Round Prominent

Condyles Small Larger

Bony Facial ConvexitY More obtuse with growth More obtuse with growth (similar to females)

Soft Tissue Convexity More acute with growth More acute with growth

Soft Tissue Thickness lf treated near end of sPurt, then Thicker profile less soft tissue change compared to boys at same (except at Nasion) maturational age. Greater increase over a larger time span.

Lips Less increase in length and Thicker, longer lips thickness than males More protrusive

Early Maturing Subjects Greater soft tissue thickness Soft tissue thickness more (11-14 year olds) pronounced in males

The onset of the spurt is delayed in boys and this delay in exposure to sex steroids may allow an overall increase in adult height (Kelch, 1987).

In females, the elevated level of oestrogen assists in the onset of menache, but inhibits further musculoskeletal growth. Males lack this elevated blood oestrogen, and therefore lack the musculoskeletal system inhibition (George, 1937). The precise mechanism for cessation of the male adolescent growth spurt remains elusive. LITERATURE REVIEV/ 26

Figure 2 The total increments of size increases for males and females aged 7 to 18 years

Prn C Pñ

2.7 t1

LS 4.2 15

d Pg'

? PTV

( in millimetres) Nanda et al', 1990.

2.3 COMPARISON BETWEEN ''NORMALS'' AND CLASS II PATTERNS

Individuals with Class I skeletal and dental relationships with harmonious soft tissue profiles are generally considered to be "normal".

Class II patients represent a majority of the patients treated in orthodontic practices and their growth potential is yet to be understood in its entirety. There exists a vast amount of individual variation, but there are a number of general morphological possibilities (Fisk et aI.,1953; Moyers, 1988; Graber, 1997b). The Class II malocclusion describes a variety of conditions ranging from very simple to vastly complex. These individuals do not grow in the same amounts or direction, and do not have the same expectations of treatment success (Mills, 1991; Graber, I997b). Rakosi (I997b) described five basic Class II types, whereas Fisk et al, (1953) previously described six. Graber (l99lb) noted the existence of up to 64 different types of Class II individuals. Moyers (1988) extensively classified Class II malocclusions into combinations of six horizontal and five vertical subgroups. LITERATURE REVIEW 27

This variation has ensured previous attempts to find a universal appliance to treat all Class II malocclusions have failed (Rakosi, I991b).

Often the maxilla is well-positioned with respect to cranial base, but the mandible is retrusive or retrognathic (Drelich, 1948; Ctaig, 1951; McNamara, 1981b). Ricketts (1952) determined anterior condylar displacement was often present prior to treatment being instigated. Maj et al. (1960), found the total mandibular length to be normal in 96Yo of Class II patients. Apparently Rothstein (1971) ( in Bishara et al., 1994) agreed with Maj et al. (1960) with respect to the length of the mandible and went further to say the problem lay in the maxilla, which was often protrusive. Class II division one patients vary morphologically in their dentofacial relationships, respond differently to treatment and have a unique growth pattern (Bishara et al., 1994). This growth may be unfavourable thus making treatment more difficult. These patients all have overbite, overjet, ANB angle and soft tissue convexity which all differ from typical Class I individuals, thus when assessing treatment results a comparison needs to be made with a comparable control group. This untreated sample is difficult to obtain, due to ethical obligations. Thus little has been published on long-term changes which occur in untreated subjects with this malocclusion'

Many researchers compare their results to cephalometric standards of normal Class I patients with subjectively good face patterns (Fisk et aL, 1953; Hitchcock, 1973; Pancherz, 1gg7). Drage and Hunt (1990) studied the effects of the Andresen activator and the bionator, and compared them to twenty-four untreated Class II division one subjects (mean age of 11.8 years). Carter (1987) had previously reported on dentofacial changes in thirty untreated subjects, but failed to disclose any soft tissue changes.

2.4 FUNCTIONAL APPLIANCE EFFECTS

2.4.1 MECHANISM OF GROWTH MODIFICATION, TIMING AND

CONTROVERSIES

When a skeletal discrepancy exists, the ideal is to be able to modify the growth pattern with a functional appliance and thus correct the skeletal problem. This is possible only LITERATURE REVIEV/ 28

in a growing patient, otherwise camouflage or surgery are the only other options (Fields, 1ee3).

Obtaining a new " morphologic pattern" following a new " functional pattern" (Carels and van der Linden, 1987) may not necessarily be stable. Orthopaedic and dento- alveolar effects are seen in different proportions according to different studies (Bishara andZiaja,1989; Fields, 1993;Pancherz, 1997). This is thought to be in the range of 30Yoto 40% skeletal and 60Yoto70o/o dento-alveolar.

A number of possible mechanisms, which may be interrelated, are thought to be involved in growth modification and in spite of the considerable research the mode of action remains obscure. Johnston (1986) indicated that functional appliances may all have a similar mode of action by unloading the joint. Petrovic and Stutzmann (1997) also noted that the Fränkel appliance, the Clark Twin Block and the Herbst may have similar physiologic mechanisms of action on sagittal growth of the mandible. This is contrary to previous research on rats by Pertovic (1984) where responses appeared to depend on the functional appliance employed. The condyle may not be alone in its involvement, thus cephalometric evaluation needs to look further than the evaluation of mandibular length.

ABSOLUTE INCREASE IN SIZE

Absolute increases in size have been detected in animal experiments with distraction of the head of the condyle from the fossa, and changes at the cellular level were seen (Petrovic et al., 1975; McNamara, 1975, 1980; Hinton and McNamata, 1984). In primate experiments, most change was completed within 12 weeks (Panchetz, 1997). Petrovic and Stutzmann (1997) reported no genetically determined final length of the mandible in animal experiments. It is likely to expect similar changes in humans (Fields, Igg3), but considerable controversy exists (V/oodside et al., 1987; Isaacson et al., 1990).

The major problem lies with respect to ethical considerations resulting in the lack of a suitable control sample and the inability to perform a double-blind study. Even if groups are matched for sex, age, skeletal pattern, and malocclusion, they may not grow in a similar manner without treatment. Animal studies allow availability of genetically identical controls, however, direct comparison to human situations is not possible. The masticatory system is not directly comparable since there are significant anatomical differences. These animals do not suffer from skeletal malocclusions and it is not LITERATURE REVIEV/ 29

possible to reproduce the way the appliances are worn in humans (Dermaut and Aelbers, 1996). Superimposed is the fact that individual growth variation is encountered. This provides insight into the reasoning for the controversies which arise.

If the absolute increase in size is very small, then measurement errors may lead to changes having little or no clinical significance. Research suggests that one millimetre of additional bone at the condyle may be expected (Woodside et al., 1987; Isaacson et al., 1990) but may be only a transient increase (McNamara,1975; Mills, 1983).

Horizontal expression of growth may be seen following removal of adverse environmental influences (Woodside et aL,1987; Moss, 1997).In dolichofacial patients, buccal segment eruption may be inhibited, allowing relative intrusion, to produce a more horizontal growth pattern (Woodside et al., 1987).

Intermittent changes in the condylar position, for instance, with activators worn primarily at night, show intermittent changes in the condylar-glenoid fossa relationships. No clinically useful increase in mandibular length has been detected (Vargervik and Harvold, 1985).

Animal experiments with continuous change in condylar position show proliferation, histodifferentiation, and even cell mitosis at the condyle (McNamara,1973, McNamara and Carlson, 1979; McNamara et a1., 1975; Petrovic et al., 1981; Stutzmann and Petrovic, 1997). Continuous alteration of mandibular position within the neuromuscular environment produces condylar remodeling and an increase in mandibular size (Woodside et al., 1983; Hinton and McNamara, 1984; Rakosi, I997b). Condylar proliferation and increased mandibular length however may be age related, being seen exclusively in the juvenile (V/oodside et a1., 1987).

An appliance that holds the mandible rigidly forward does not activate the lateral pterygoid muscles and may not stimulate condylar growth (Rakosi, 1997a). Human experiments with these biomechanical conditions would be markedly beneficial. 'Woodside (1997) assessed nocturnal activator wear on mandibular growth and found no clinically useful increases. With altered stress at the condylar area, by chewing while holding the mandible open with biteblocks, signif,tcant increases in mandibular length were detected (Woodside, 1997). Continuous change in condylar stress requires full- time wear (Woodside, 1997). Functional appliances worn on a full-time basis include LITERATURE REVIEV/ 30

the Clark Twin Block and the Herbst appliance. Fixed Herbst appliances in humans (pancherz, 1979; V/indmiller, 1993) have been reported to increase mandibular length following lateral cephalogram examination. The potential for measurement error is obvious and Pancheru (1997) attempts to limit this by including analysis of "open mouth" cephalograms. Accurate imaging of the selected temporomandibular joint and condyle is still prone to interpretation errors. petrovic and Stutzm ann (1997) detected increased condylar cartilage growth rate and subperiosteal ossification rate at the posterior border of the mandible' This produced a longer mandible in the treated animals. Lund and Sandler (199S) found a2.4 millimetre increase in articulare to pogonion in humans with the Clark Twin Block when compared to untreated controls. Keeling et al. (199S) also noted stable skeletal changes attributable to enhanced mandibular growth in 9 to 10 year-old headgear and bionator patients.

REDIRECTED GROWTH

This redirection of growth may occur in either or both, the maxilla or the mandible. It changes the spatial relationship of the jaws, thus ultimately expressing the growth in a different direction (Williams and Melsen,1982; V/oodside et al., 1987; Pancherz and 'Woodside, Fackel, 1990; Mills, 1997;Fields, L993; Graber, 7994; 1997 ).

According to the method of Björk (1968), Birkebaek et al., (1984) conducted implant studies in 23 children and determined an increase in the amount and change in condylar growth direction following ten months of activator therapy.

Condylar growth direction varies after treatment with postural hyperpropulsion, testosterone, somatotropic hormone, oï resection of the lateral pterygoid muscle (Stutzmann and Petrovic, 1997). Somatotropic hormone also produces anterior growth rotation while postural hyperpropulsion gives posterior growth rotation of the condylar cartllage (Stutzmann and Petrovic, 1997). Seasonal variations are also detected in the amount of growth (Stutzmann and Petrovic,1997).

Headgear can act as an efficient tool in redirecting growth. The force vector applied may determine the growth direction. High-pull headgear may be used to redirect the forward and downward movement of the maxilla and may control vertical maxillary growth (Graber, 1985). LITERATURE REVIEW 31

ACCELERATION OF DESIRED GROT4/TH

Changing the rate of growth involves no change in the ultimate size of shape of the mandible, but enables growth potential to be reached sooner (Williams and Melsen, 1982; Vargervik and Harvold, 1985; Pancherz and Fackel,1990: DeVincenzo, l99l; Fields, 1993: Dermaut and Aelbers, 1996; Panchetz,199l).

In his sample of human females, De Vincenzo (1991) noted the majority had dramatic increases in mean mandibular growth rate during functional appliance therapy. After four years no significant differences were seen between these patients and controls matched for age, sex and initial mandibular plane angle.

Once the lips obtain their correct position and a Class I relationship is established, the relative rate of mandibular growth decreases so that the final growth patterns of the maxilla and mandible are in harmony (Isaacson et al., 1990; Petrovic and Stutzmann, reeT).

GLENOID FOSSA REMODELING

The form of the temporomandibular joint is genetically determined but it can be modified by function (Gerber, 1990). The adolescent joint is still forming and capable of adaptation. By 18 years of age the structural development of the articular surface is complete (Steinhardt, 1990b). Remodeling of the anterior border of the glenoid fossa may occur with continued forward positioning of the condyle ( Häupl, 196l;'Woodside et al., I98l; Petrovic and Stutzmann, 1997 ) and this produces a more forward positioned mandible (Breitner, 1930,1932 cited in Joho, 1973; Häupl, 196l; Woodside etaI.,1983; Vargervik and Harvold, 1985; Woodside et a1., 1987; Degroote, 1984 cited in Norton and Melsen, lggl; Proffit, 1993). Consequently, a better sagittal relationship with the maxilla. 'Woodside and his co-workers (1987) found all experimental monkeys, including the mature adult, to have a large volume of new woven bone formed in the glenoid fossa, which appeared to correspond to the direction of tension. Voudouris (1988) and Angelopoulos (1991) detected similar changes and determined these glenoid fossa changes to be stable. This supports the findings in Hinton and McNamara's study (1984) of monkeys, which suggested that functional appliances may exert a strong influence on glenoid fossa remodelling following continuous functional appliance therapy. LTTgRETURE REVIEW 32

In primates, muscle activity beyond certain limits may interfere with bone remodeling (Woodside et al., 1983). Adaptations can occur in response to functional demands but overloading can lead to destruction of joint components (Steinhardt, 1990b). The diffrculty is in realising where stimulation stops and pathology begins in any given patient.

MUSCLE ACTION

Functional appliances reportedly alter the neuromuscular environment affecting the teeth and associated bones (Graber, 1997b). Stresses in bone have been shown to dominate the shape and architecture of bone (Harvold,1975)'

According to McNam aru (1973) several adaptive mechanisms are seen

¡ Migration of muscle attachments along bone surfaces

o Changes in dimensions of muscles due to rotations and bone displacements

o Elongation of muscle fibres or tendons

The neuromuscular response can also give adaptive changes in postural activity (Stöckli and Teuscher, 1985).

While fixed orthodontic treatment relies on the application of mechanotherapy, the functional appliance also uses removal of force systems (Carels and van der Linden, 1937). The Fränkel is a perfect example of this, with its buccal shields and lip pads (McNamara and Brudon, 1993; Stockfisch, 1995; Graber I997a).

Patients with Class II malocclusions exhibit less electromyographic activity in the masseter and temporal muscles during maximal biting in intercuspal position (Pancherz, 1930). Less electromyographic activity was detected in the masseter while chewing compared to "normal" subjects (Pancherz, 19S0). Thus muscle activity in Class II individuals may be impaired due to diverging dentofacial morphology and unstable occlusal contact conditions. LITERATURE REVIEW JJ

passive tension from the viscoelasticity of soft tissues, derived from the mandible being held forward, is important in the induction of functional appliance changes. Muscle activity is increased when the mandible is held forward by the protractor muscles, for instance the lateral pterygoid (Stöckli and Teuscher, 1985; Petrovic and Stutzman, 1997 ;'Woodside, 1997).

Moss (lg7 5) noted that the masseter muscle was active on protrusion while the posterior temporalis was passive. On retrusion though, the posterior temporalis was active (Moss, 1975; Stöckli and Teuscher, 1985), while the anterior masseter was passive. In intercuspal position, most activity was seen in the anterior masseter and the least in the posterior temporalis, with harmony between the left and right sides (Moss, 1975). Decreased unilateral lateral pterygoid function has been shown to give condylar enlargement on the contralateral side (Woodside et al., 1983).

Steinhardt (1990a) in addition to Petrovic and Stutzmann (1991) concluded that increased lateral pterygoid muscle activity stimulates proliferation of condylar tissue. Graber (1994) also states that lateral pterygoid muscle activity increases with functional appliances. In an animal model an excised lateral pterygoid muscle significantly decreased condylar growth (Graber, 1985; Woodside, 1997). Petrovic and Stutzmann (1997) noted that with a missing lateral pterygoid muscle, direct, repetitive stimulation of the retrodiscal pad elicits the same condylar response as if the muscle was intact. The possible effect of a surgical procedure and the development of scar tissue may also have an effect. LITERATURE REVIEW 34

Figure 3 The Effect of the Lateral Pterygoid Muscle.

Compiled from Graber (1985); Stöckli and Teuscher (1985); Petrovic and Stutzmann (1997) lnsertion of lateral pterygoid muscle

on condyle in physiological position o

lf hyperactive lateral pterygoid (due to functional appliance) o Traction at point of insertion

lntensification of the repetitive activity of the retrodiscal pad +

lncrease in growth stimulating factors

Enhancement of local mediators

Reduction of local regulators

(factors having negative feedback on cell multiplication rates) o

Change in condylar trabecular orientation Additional growth of condylar cartilage

Subperiosteal deposition of bone o

Functional chondroblasts (not yet hypertrophied) produce m_ultiplication restraining signal. Th.us wñân ìtlò number of chondioblásts óècreades, tliei negative feedback signal decreases, thus the prechondroblast multiplication rate increases. o

Supplementary lengthening of mandible.

The influence of the lateral pterygoid implies transmission of information either by an electrical, chemical or biomechanical natute (Stutzmann and Petrovic, 1979). Joho (1973) could not detect if there was bone deposition at the insertion of the lateral pterygoid or remodeling with reorientation of the trabecular system. Condylar unloading was seen with full time wear (V/oodside,1997). Tissue proliferation \ilas seen to fill the area behind the condyle (Clark, 1997). This may be in agreement with Johnston (1986) who suggests all functional appliances have a similar mode of action. Stutzmann and Petrovic (1997) noted retrodiscal pad stimulation produces a more posterior relocation of dividing cells of the condylar cartilage. As retrodiscal pad activity increases, the rate and amount of condylar cartilage growth increases (Petrovic and Stutzmanî, 1997). LITERATURE REVIEV/ J)

Not only may the lateral pterygoids supply the functional stimulus but also the blood and nutritional supply and may be the final pathway of the cartilage metabolism for the condylar response (Graber, 1985; Petrovic and Stutzmarn,l99T)'

McNamara (1930) had detected an initial increase in the activity of the muscles of mastication with insertion of a functional appliance and a decline back to pre-treatment levels after three months. McNamara and co-workers (1987) also noted a five to six times increase of the chondroblastic layer thickness when compared to their control animals. Likewise Petrovic and co-workers (1975, 1981) describe an increase in cellular activity at the condyle using a parameter of thymidine uptake. One explanation may entail a "filling in" of bone into the space which is left, in response to vertical growth at the dentoalveolar process, once the mandible is displaced forward by the functional 'Whetten appliance. In contrast, and Johnston (1985) were unable to determine a growth regulatory effect in an animal model using radiographic techniques following 'Woodside's hyperpropulsion of the lateral pterygoid muscles. In primates, lateral pterygoid activity was seen to decrease for 18 weeks after functional appliance insertion (V/oodside, 1985). Sessle et al. (1990) also found a decrease in postural activity ofthe lateral pterygoid in addition to the superficial masseter muscles fot 12 weeks prior to returning to pre-treatment levels. In addition, progressive mandibular advancement did not stop the decrease in postural activity. Pancherz (7997), discussed unpublished primate experiments conducted by McNamara, that describe apposition at the condyle being complete within 12 weeks, with a less marked skeletal response at the lateral pterygoid.

Unfortunately, it is still not established whether active muscle contraction or passive muscle tension is the primary stimulus for growth with functional appliances (Clark, 1995). Petrovic and co-workers (1981 ,1997) concluded that stepwise activation is the most effective way of lengthening the mandible because it increases lateral pterygoid activity and increases the rate and amount of condylar cartilage growth'

At night condylar cartilage and alveolar bone of growing children have a higher percentage of cells in the DNA-synthesis phase. Growth and the length of the lateral pterygoids tends to be more important at night. This may render some appliances more biologically effective if worn nocturnally (Petrovic, 1994; Petrovic et al., 1997). LITERATURE REVIEW 36

Flexible appliances with minimal opening which do not impinge on the rest position, like the Fränkel, produce a neuromuscular response with isometric contraction producing the force. Rigid appliances, especially with considerable mandibular opening, produce passive stretching of muscles (Graber, 1985; Isaacson et al., 1990). If the freeway space is exceeded, as with some common activator designs, viscoelastic properties of the associated tissues maybe elicited to maintain a corrective stimulus at night (Harvold, 7974). These effects may be detected via electromyographic studies (Eschler, 1962). During each application of force, secondary forces arise within the tissues. The visco-elastic process can be divided into five stages (Rakosi, 1997a)- o Emptying of vessels. o Pressing out interstitual fluid' o Fibre stretching, o Elastic deformation of bone.

. Bioplasticadaptation.

This rigid stretch introduces no myotactic reflex, but a build-up of potential energy

RAMAL FORM

Regional gradients of remodeling may occur and gonial angles may change during active treatment (Joho, I9l3; Pancherz, 1979; Pancherz and Fackel, 1990). Moving the mandible to a new position within a muscle system results in rearrangement of the stress distribution and reorganisation of shape and internal structure (V/oodside et al., 1983).

The gonial angle changes to accommodate effects of mandibular displacement rotations (Enlow, 1975). Changed activity and tone of the pterygomasseteric sling may change the gonial angle (McNamara, 1980). This is detected in both animal and human experiments.

Reduction of the gonial angle may influence mandibular length (Pancherz, 798I; Petrovic et al., 1981) and mandibular morphology. It may also alter with postural position (Harvold, 1975 Petrovic et al.,1975). LITERATURE REVIEV/ 37

Figure 4 Gontrol mechanisms of condylar cartilage growth rate in rats.

Compiled from Stutzmann and Petrovic (1997)

Postured moving mandible o lncrease lateral pterygoid contractile activity + Stimulate retrodiscal pad oo lncrease number of dividing cells Dividing cells relocated posteriorly o Posterior growth direction of condyle o

Change ramal form; lncreased gonial angle o

Need good interdigitation to maintain new gonial angle (otherwise angle closes again) o

Anterior positioned mandible

O feedbacksignal Decrease lateral pterygoid contraction.

Movement of retrodiscal Pad. o

Decrease condylar growth rate.

MAXILLARY RESTRICTION

Midface restuiction is an important factor in achievement of Class I (Harvold and Vargervik, l97l: Pancherz, 1979; Yargervik and Harvold, 1985; Windmiller, 1993). Forward maxillary growth can be changed to correlate to that which is achieved with headgear correction (Op Heij et al., 1989; Isaacson et al., 1990; Tulloch et al., 1997b). Inhibition of maxillary growth is not limited to the active growth spurts even if it is effective during them (Rakosi, 1997b).

Appliance design may vary but advancement of the mandible by the appliance is expected to result in retrusive forces in the maxilla (Vargervik and Harvold, 1985). In a review on activators and Herbst therapy, inhibition of maxillary growth was detected in LITERATURE REVIE'W 38

thirty-three percent of patients (Aelbers and Dermaut, 1996). Headgear provided maxillary restriction in a hundred percent of patients. In their review Aelbers and Dermaut (1996) note changes in maxillary length between experimental and control groups never exceeded one millimetre'

Selection of A-point to determine maxillary restriction andlot redirection may compromise " true" results since it is influenced to some extent by dentoalveolar remodeling (Mills, l99l).

DENTOALVEOLAR CHANGES AND SOFT TISSUES.

The Class II malocclusion can be converted to Class I by preventing eruption of the upper posterior teeth and vertical manipulation of the occlusal plane.

The dento-alveolar changes are a major part of the treatment effect and in non-growing patients only dentoalveolar changes are possible (Fields, 1993; Clark, 1995; Pancherz, teeT).

Certain ratios can be applied to the amount of maxillary incisor retraction and upper lip retraction. Many such ratios are quoted throughout the literature (Talass et al., 1987; Holdaway, 1983) but they may not be clinically useful. Initial overjet and retraction of maxillary incisors may not be the most important factors influencing retraction of the upper lip (Wisth, 1974). The morphology of the upper lip and the anatomy of the "nose- upper lip complex" may play a significant role in upper lip retraction (Talass et al., 1987). Lip tension at rest and when the cephalometric radiograph is taken is paramount. The complex anatomy of the upper lip cannot be fully analysed by cephalometric radiographs. The interrelations between the upper lip muscles and the anatomy of the " nose-upper lip complex" should be considered as well as profile changes. Lip strain, morphology, àEC, sex and type of treatment may all interrelate to play their influence (Finnöy et aI., 1987). Riedel (1957), Bloom (1961) and Rudee (1964), reported correlations between incisor movement and soft tissue changes.

Verdonck and co-workers (1993) were unable to find a relationship between soft tissues and the sagittal position of the dentition, but this study is diff,rcult to perform accurately since it involves measuring the surface area of the lips on the cephalogram and equating LTTSRRTURE REVIEW 39

it to tooth positions. Posen (1976) considered the strength of the lips and determined a correlation with malocclusion. That is, normal tonicity produces a Class I occlusion, hypotonic lips produce a patient with bimaxillary protrusion and hypertonic lips produce a situation with the dentition set back on their respective apical bases. He also states that if a patient's lip tonicity is in the normal range he will generally have little or no difficulty in keeping the mouth closed in repose. Unfortunately Posen's work was later questioned as it was not reproducible (Ingervall and Jansen, 1981).

Talass et al. (1987) determined that prediction of upper lip retraction was unreliable. Various lip thickness at certain points may determine the amount of retraction detected.

Greater lip retraction seemed to take place with : o Greater amount of maxillary incisal edge retraction o Thinner soft tissues at " subnasale" before treatment, thus allowing easier displacement once there is retraction of the underlying hard tissues

o Thicker upper lip measured between labrale superius and the labial surface of the upper incisor, allowing a mote potent muscular force to be applied to the underlying hard tissues. This is contrary to Oliver (1982).

o Greater vertical nasal growth.

However, these factors explained only 48.5% of the variability of the upper lip response.

The significant changes detected with upper incisor retraction were upper lip retraction, increased nasolabial angle and increased lower lip length. The changes which had little clinical significance were retraction of the lower lip (Huggins and McBride, 1975), decreased interlabial gap, increased thickness of both the lips and a soft tissue increase in lower face height, No change was seen in the length of the upper lip (Talass et al, 1987). Increased lower lip length appeared to occur when there was a longer lower lip or greater amount of the upper incisor crown covered by the relaxed lower lip. In addition, the lower lip length increased if the orthodontic treatment increased hard tissue lower face height (Talass et al., 1987).

Huggins and McBride (1975) found no correlation between upper incisor position and lip position in males, whereas in females retraction produced a reduction in lower lip LTTgRRTURE REVIEW 40

prominence and, in patients with a Class I dental base relation, prominence of the upper lip. Nanda et al. (1990) also attributed some soft tissue profile changes to sexual dimorphism with males having a greater increase over a larger time span.

Basically, functional appliances seem to result in decreased forward growth of the maxilla and retraction of the upper incisors. The mandibular incisors may be protracted or in certain circumstances may not change. There is an increase in height of the mandibular alveolar process and an increase in lower face height. The amount of increase in the forward growth of the mandible could not be consistently determined (Creekmore and RadneY, 1983)'

Treatment Timing

Not only is growth direction important, but so is the growth potential available (Rakosi, Ig97b). The ideal time to modify growth is generally thought to be during the rapid growth period of the mixed dentition just before puberty (Isaacson et al., 1990; King et al., 1990; Nielsen, 1995). This allows an uncomplicated second phase of treatment (Fields, Ig93). This is especially true in females, as puberty has an earlier onset than in males. Trenouth (1989), Clark (1995), Pancherz (1997) and Ghafari et al. (1998) believe the timing is not necessarily so crucial as long as the patient is " actively growing". Pancherz (Iggl), prefers to actually treat his functional appliance patients a little later; just as they are moving out of their adolescent peak growth. This is to avoid excessive relapse due to the effects of future growth (Pancherz, 1997 Ghafari et al., 1998). Successful treatment is dependent on stable cuspal interdigitation, no oral habits, favourable growth patterns and retention or overtreatment (Pancherz, 1997).

Functional appliances change the expression of growth but may not control the underlying growth pattern (Fields, 1993).

Functional appliance therapy should not be commenced in the juvenile growth spurt, even though there is a rapid growth rate. The skeletal discrepancy is quickly overcome, however it tends to relapse due to the original expression of growth reasserting itself. Contrary to this, one could also argue that allowing near full expression of the underlying pattern leaves little opportunity for significant change' LITERATURE REVIEW 47

If treatment is initiated too early then intercuspation and the promotion of occlusal stability is not achieved. Retention time needs to increase until growth is complete. Orthodontists who treat in this phase, however, attempt to normalise the soft tissues and the skeletal components early, thus producing normal growth ( Ngan et al., 1988; Fields, r9e3).

After puberty the mandible continues to grow (Behrents, 1997), but not suff,rciently to correct a signif,rcant skeletal discrepancy (Fields, 1993), thus treatment timing is optimal near the adolescent growth sPurt.

Chronological age can not be used efficiently to estimate mandibular growth capacity (Proffit, 1993). It is poorly correlated with other measures of skeletal maturation. Hägg and Pancherz (1988) recommend velocity curves of standing height or the radiographic analysis with skeletal maturity indicators employing the third phalynx of the middle finger, as a measure of facial growth. Greulich and Pyle (1959), Björk and Helm (1967), Bowden (1970), and Fishman (1982) also employed the hand-wrist as an indicator of skeletal growth.

Morris and co-workers (1998) detected a possible "trend" between standing height measurements and soft tissue parameters. Other parameters which may be useful in the overall assessment of growth estimation include, the presence or absence of secondary sex characteristics, dental age, including "Stage G" of root formation of the mandibular canines (Chertkow, 1980), and vertebral predictors ( Lamparaski,l9T2). Possibly in the future the use of blood tests to analyse hormone levels such as follicle stimulating hormone, luteinizing hormone, oestrogen and testosterone, may be a better indicator of true growth potential (George, 1987).

C ontr ov er s ie s Enc ompas s ing Gr owth Theor ie s

A number of craniofacial growth theories are relevant to understanding the possible mechanisms of functional appliances.

These growth theories include genetic control (Enlow, 1990), bone as a primary determinant of growth (Enlow, 1990), or cartilage as the primary determinant of growth. LITERATURE REVIEW 42

The synchondroses and nasal septum appeff to be growth centres but the condyle appears to be reactive (Proffrt,lgg3) and lacks innate growth potential. Petrovic et al. (1931) attemptto describe the servo-system. Primary cartilage grows from cell division of chondroblasts, whereas secondary cartilage growth is by division of prechondroblasts. The dividing cells are not surounded by a cartilaginous matrix and thus are influenced by local extrinsic modulating factors, which influence the growth rate of secondary cartilage. In primary cartilage the chondroblasts produce an intercellular matrix which isolates the dividing chondroblasts and local factors can not restrain or stimulate the cartilage growth rate. With primary cartrlage, orthopaedic appliances for Class II correction modulate direction but not the amount of growth, whereas with secondary cartilage they modulate both direction and magnitude.

Moss (7962, 1997) discusses the possibility of the periosteal or capsular functional matrix playing a vital role in growth modulation. Epigenetic, extraskeletal factors and processes are the primary cause of all adaptive, secondary responses of skeletal tissues and organs (Moss, 1997). The informational content of the intrinsic skeletal cell genome does not directly regulate the responses of the bone and cartilage (Moss, 1997), but environmental influences are also providing an effect. The sum of all the biophysical, biochemical and genomic attributes of the bone cell can not predict the higher attributes of a bone tissue (Moss, 1997).

The growth of the face responds to functional needs and there is a compensatory response of cartilage and bone. The Functional Matrix Theory (Moss, 1962) has been revised (Moss, 1997) to encompass cellular mechanotransduction and the biologic network theory. LTTBRETURE REVIEW 43

Figure 5 Bone adaptation due to mechanoreception and mechanotransduction.

Compiled from Moss (1997)

External Environment s

Irritates Cell

+

Mechanosensing (thus cell responds to extrinsic loading) ++ A. MECHANORECEPTION B. MECHANOTRANSDUCTION

Transmits extracellular physical stimulus Transduces/ttansforms stimulus's energetic orl&

into a cell receptor. informational content into an intracellular signal.

Eg. Ionic or Electrical S + +

BONE ADAPTATION

(Bone adaption requires intercellular transmission of transduced signals and information is moved hierarchically downward towards the osteocytes). LITERATURE REVIEW 44

STIMULUS

o

EXCEED THRESHOLD

o

TISSUE RESPONDS

o

Movement of information to osteocytes

a Ionic or chemical processes; passage through plasma membrane, with subsequent intercellular transmission, which then regulates bone cell responses.

a Stretch activated channels; strained bone tissue, produces a strained plasma membrane, with subsequent activation of ion channels, which can initiate intracellular electrical events.

a Electrical processes (electromechanical, electrokinetic, electric field strength). Bone responds to external electríc /ields.

a Mechanical ; the straíned extracellular matrix may transmit information to the bone cell nuclear membrane, and the properties of the extracellular matrix may alter cell behaviour o

o

ADAPTATION

Figure 6 Bone adaptation due to threshold exceeding stimulus

Compiled from Moss (1997)

The orofacial region is a complex unit (V/oodside et a1., 1983; Berkoviiz and Moxham, 1988; McMinn et al., 1992). There are twenty-four muscles attached to the mandible and teeth are in an equilibrium between opposing forces. The muscles from the cheeks, lips and tongue are involved in producing and sustaining this equilibrium. Any changes, via factors altering duration, direction or magnitude of the muscle force will affect the equilibrium (Graber, 1994). Resting pressures, although smaller, act for longer and are perceived to play a larger role than the more marked intermittent lip pressures during swallowing (Proffit, 1 978). LITERATURE REVIEV/ 45

Distinct patterns of activity are associated with different malocclusions (Moss,1975). This may be due to the fact that nature places them where they should be, so as to best adaptto their needs (Moss, I9l5). Possibly functional appliances can be adapted to the type of anomaly and the growth pattern for which they are required'

The tongue, lips, facial and masticatory muscles, ligaments and periosteum can be altered depending on the components of the functional appliances. Thus the functional appliances provide new patterns of function, which lead to the theoretical development of a new morphologic pattern (Carels and van der Linden , 1987). This may be due to the improved occlusion, an altered arrangement of teeth within the jaws, and/or an altered relation of the jaws. There may also be differences in the facial size and proportions (Carels and van der Linden, 1987).

A complex relationship exists between form and function (Moss, 1975) and McNamara (1980, 1981a) demonstrates this intimate relationship with his numerous animal experiments. If function totally dictates form, then altering function with a functional appliance will allow development of a new morphology. In the short term though, form dictates function. For instance, large adenoids predispose to mouth-breathing. In the long term some researchers believe there is development of an " adenoid face", with a narrow maxillary arch (Schendel et al., l97C Linder-Aronson et a1., 1986; Tourne, 1990). This, is however, controversial.

Figure 7 details the gradual changes and effects of functional appliance insertion, as revealed by McNamara (1980) in his numerous animal experiments.

The animal experiments by McNamara (1980) revealed not only a close relationship between structure and function in the craniofacial region but also a rapid neuromuscular response followed by a more gradual skeletal adaptation producing skeletal harmony. LITERATURE REVIEV/ 46

Figure 7 Gradual structural changes due to functional appliances.

Compiled from McNamara (1980)

Functional appliance insertion

o

Increased activity of muscles of mastication

(as determined by new occlusal position)

& l-7 days

Changed activity-decreased temporalis (posterior head)

-increased masseter activitY

-increased lateral pterygoid (superior head)

n New equilibrium in i weel

Higher activity level (than pretreatment level)

! 4 weelc; further adaptation wíthin muscles

Decline in activity

A 4 weeks

Activity similar to pretreatment levels

(at 3 months after insertion of functional appliance )

+

Gradual structural changes

Moss (1975), demonstrated that muscle activity of Class II division I individuals increased in all muscles after functional appliance therapy, compared to children with a normal occlusion, and was actually similar to the muscle activity present in adults with normal occlusions. Exercising the muscles, with the use of the functional appliance LITERATURE REVIEW 47

probably caused the increase in muscle activity (Moss, 1975). Moss (1975) also stated that the " absence of change" in the muscle patterns is an indication of failure of the soft tissues to adapt to the new tooth positions. Thus muscle activity may provide us with an idea of stability.

As the soft tissues develop they have a role in the differentiation and morphology of their bony attachments via osteoblastic and osteoclastic activity (Moss, 1997).

Forces used for growth modification may be intrinsic or extnnsrc.

Extrinsic forces include headgear application where heavy intermittent force provision increases skeletal change and limits tooth movement via hyalinisation, whereas light forces with full-time wear increases the proportion of tooth movement (Proffit, 1986).

Intrinsic forces include muscular fotces, as seen with the Clark Twin Block and Fränkel appliance. This force is difficult to measure and often variable. Fränkel (1983) estimated approximately 500 grams in the retractor muscles when the mandible is displaced forward 8 millimetres. Eruptive forces also fall into this category, and are thought to be in the vicinity of 5 grams. Depending on where teeth erupt they may influence the apical base and alveolar process (Fränkel, 1983).

2.4.2 APPLIANCE TYPES AND SUMMARY OF EFFECTS

There are numerous functional appliances, with multiple variations and modifications (Trenouth, 19S9). Treatment time is typically twelve to eighteen months and within this time each variety of appliance may be expected to produce a slightly varying response (Cura et al., 1996).

The Fränkel changes facial growth in mainly a vertical plane (Neilsen, 1984; Mills, 1991) and all patients apparently have improved facial profiles. The activator gives marked upper lip retrusion and anterior positioning of soft tissue pogonion and is successful in treating Class II patients (Forsberg and Odenrick, 1981). In reviewing the literature there apppears to be a lack of published data on the effects of the Clark Twin Block on the soft tissues. Clark (1995) treated patients and compared the Clark Twin Block results against published standards but only noted the skeletal and dental changes. LITERATURE REVIEV/ 48

The Combined Activator- Headgear Appliance

THE ATOR

tl P

Figure I Activator with headgear tubes (used in the present study)- frontal view

're+¡L;-

Figure 9 Activator with headgear tubes (used in the present study)- side view LITERATURE REVIEW 49

Teuscher recommends the use of the activator with headgear (Stöckli and Teuscher, 1985; Graber, I997b). This appliance was initially shown by Pfeiffer (1972) to reduce the length of treatment (cited in van Beek, 1982). There are many variations described in the literature and many diverging results. This may be due to not only the variation of appliance design but also the method of investigation and the facial type and growth pattern of the patients. The design of a particular study may make it difficult to accurately compare results to other studies. The measurement approach may also disguise the change. If a researcher measured prognathism from a perpendicular to SN-7 through sella, pogonion may have advanced more than normal following functional appliance therapy. However, the analysis, and measurement of condylion - pogonion by another researcher may have determined no change. Remodelling of the glenoid fossa may have been the concealed factor.

The type of headgear applied is of great importance. For instance, with cervical headgear the maxilla is retracted and moved inferiorly and thus the mandible moves down and back, the patient appears more dolichofacial, and the profile appears worse. High putl headgear is needed to control the vertical maxillary growth. By controlling the maxilla from moving down, forward autorotation of the mandible may occur. Horizontal mandibular growth helps improve the profile (Bishara and Ziaja, 1989). If the force vector of the high pull headgear is below the centres of resistance of the maxilla and dentition, it causes posterior rotation of the maxilla and dentition, incisors are extruded and molars are relatively intruded (Stöckli and Teuscher, 1985). The best vertical control clinically with minimal rotation of the occlusal plane and a minimal amount of rotation of the maxilla and its dentition is when the force vector runs between the centres of resistance of the maxilla and the upper arch (Stöckli and Teuscher, 1985; Graber, 1997b). The ideal force vector providing no rotational effects is through the centres of resistance of both the upper arch and the maxilla. This however is almost impossible to achieve clinically. LITERATURE REVIEV/ 50

Figure 10 Gentre of Resistance in the Maxilla.

A force vector would need to pass through the centre of resistance of the maxilla and dentition, so as to ensure no rotational component was induced (Graber, 1985)'

t\I'

Graber (I997b) deducted that the activator has the following effects: o prevents, intercepts, and corrects habits (lip sucking, abnormal swallowing, digit or lip sucking). o acts as a space maintainer.

. expands the arch ifnecessary.

o starts to correct individual tooth positions and deepbites.

. helps correct the Class II relationship by:

o preventing habits and reorienting physiologic forces

o promoting mesial movement of lower teeth and distal movement of uppers

o inhibitingmaxillarydevelopment LITERATURE REVIEV/ 51

Nielsen (1995) reported 80% of treated patients had restricted downward and forward maxillary growth and the mandible grew forward to some degree in 70%o of patients' This results in an improved sagittal jaw relation. Soft tissue profile change may follow. Reports on the soft tissue profile, however, are scarce.

Luder (19S1) noted females exhibited a more downward and backward rotation of the mandible. Later he related this to the construction bite (Luder, 1982). A thicker construction bite tended to produce a more upward and forward rotating growth pattern due to redirection of condylar growth.

A limited number of skeletal Class II patients can be treated exclusively with the combined activator-headgear appliance. In patients with vertical patterns of groWh the activator is used as a bite block thus preventing eruption of molars and premolars and encouraging upward and forward mandibular growth.

Luder (1981) detected differences in reactions with activator treatment between boys and girls. In explaining his inconsistent results he provided a possible explanation of different modes of action of the activators. The construction of the appliance may influence the result. The overlying soft tissues would also be affected, by the alteration of the underlying skeletal and dental components'

The effects of the activator and headgear used by van Beek (1982,1984) were as follows:

Restrained maxilla Vertically and sagittally.

Stimulated mandible Variable and temporary mandibular growth.

Decreased convexity Variable (van Beek, 1982).

Upper incisors retroclined Often beneficial.

Upper incisor intrusion Often beneficial.

Upper posteriors tilted distally This may be an indication that the overjet is being

corrected dentally, rather than orthopaedically,

Molars erupted Enhanced, to level curve of Spee in deep bites.

Inhibit molar eruption in openbite tendency cases. LITgRRTURE REVIEV/ 52

Increased face height If not acting as a bite block.

Lip seal To convert a mouthbreather is difficult (1984).

If lack a lip seal do not extrude the lower molars to level the curve of Spee.

Lower incisors proclined Proclined even if capped (due to fulcrum effect).

Ideally, there is a need to overcorrect the Class II, correct the overjet and lip seal, in addition to providing firm intercuspation. Stability is also dependent on a balance of the contribution of the condyles, the glenoid fossae, the growth of the maxilla and the dentoalveolar process (Stöckli and Teuscher, 1985). Ten to twelve hours per day of appliance wear provides a rapid overjet correction. A25% relapse was detected, in the order of a 4 millimetre overjet within a three year period (van Beek, 1984).

Stöckli and Teuscher (1985) state that the Class II skeletal relations treatment result is determined by the amount of inhibition of the anterior displacement of the maxilla. The less the maxilla requires to be held and the more the condyle can be promoted and encouraged to " grow" then the greater the skeletal and profile improvement. Otherwise there is often an increased face height and lack of profile improvement (Stöckli and Teuscher, 1985).

Patients with a good skeletal pattern at the start of treatment attain a good lip balance after treatment, whereas patients with an initially high or low mandibular plane angle and a poor chin, lip and nose relationship attained a less favourable lip balance after treatment (Forsberg and Odenrick, 1981).

Decreased forward movement of incisors and molars with inhibited vertical dentoalveolar development of upper incisors have been noted but no vertical difference was detected in molars when compared to controls (Stöckli and Teuscher, 1985; Neilsen, 1995). This produces an anterior occlusal plane rotation with the upper molar erupting vertically but not forward, The maxilla and the maxillary dentition are actually held while growth occurs around them. The condyles grow more posteriorly, but they have the same vertical increase as the controls (Stöckli and Teuscher, 1985; Neilsen, 1995). Incisor positions were not changed (Stöckli and Teuscher, 1985; Cura et a1., 1996). Pogonion was advanced and the relative retrusiveness of the lips increased (Forsberg and Odenrick, 1981). Basically, the anterior rotation of the mandible probably LTTBRRTURE REVIEV/ 53

occurs mainly due to its change in shape and less backward and more downward remodeling of the glenoid fossae.

The main soft tissue effects with activator use, but without headgear (Forsberg and Odenrick, 1981), were:

o upper lip retrusion.

a soft tissue pogonion moved forward

a no change in the tip of the nose (equal forward growth as control patients)

o lip retraction did not correlate with overjet reduction on a one to one basis. The upper lip had a 0.33 conelation with overjet reduction, while the lower lip had a 0.16 conelation.

satisfactory soft tissue response was not seen in all cases, mainly due to down and back rotation of the mandible. LITERATURE REVIEW 54

The Clark Twin Block

THE CLARK T\ryIN BLOCK

Figure 12 Cla¡k Twin Block (as used in the present study)- side view LITERATURE REVIEW 55

The Clark Twin Block was developed in 1977 . It is a very efficient, comfortable and aesthetic functional appliance comprising two parts that is worn full-time (Clark,1982, 1988, lgg5, lgg7,l9g8). It is the natural progression from the original monobloc and the double plate of Schwartz. The two portions meet together on a 70 degtee incline plane. This allows interlocking to posture the mandible forwards with an appropriate horizontal force (Clark , lg97). This is a modification of the original 90 degree incline plane which required a conscious effort to occlude. Originally, in 30Yo of patients there were problems maintaining the forward posture (DeVincenzo et al., 1987)' Patients were slipping out of the appliance, and occluding incorrectly such that posterior open bites would develop (Clark, 1995). These patients usually had weak muscles and a vertical growth pattern (Clark, 1995). The force of occlusion is used as a functional mechanism to correct the malocclusion because the unfavourable cuspal contacts are extinguished and favourable proprioceptive contacts are provided. As detected by McNamara (1980) this influences the rate of growth and the trabecular structure of the supporting bone (Clark, 1988, 1997).

Carels and van der Linden (1987) determined that no adverse biological reactions are detected with a one step advancement of the mandible via a functional appliance like the Clark Twin Block. However, an initial slight discomfort may occur as compared to the gradual advancement of the Fränkel. Maximal activation of a functional appliance should not exceed seventy percent of the total protrusive path of the mandible so as to maintain function within the physiological range (Clark, 1997). The Clark Twin Block may be used with incremental advancement if the overjet is greater than ten millimetres, or if the full arch relationship is not corrected.

In patients with temporomandibular joint dysfunction, activation should not be beyond the tissue tolerance so as to allow the patient to rest and function without discomfort. If the patient is " a vertical grower" gradual advancement of the mandible allows time for compensatory mandibular growth. Often these patients have weaker muscles (Stöckli and Teuscher, 1985; Clark, 1995), and there is a decreased functional response.

In the first three months there are only soft tissue changes and bony changes take longer to occur. Treatment consists of a 12 month phase. Overjet and overbite are corrected, and Class I molars are progressively achieved by controlled trimming of the upper appliance. This allows lower molars to erupt and level the occlusal plane. Time is needed for growth modifrcation to occur. LITERATURE REVIEV/ 56

With the support phase, the corrected incisor relationship is maintained until the buccal segments fully interdigitate (Clark, 1995,1997). Fult-time wear continues through this phase to allow the internal bony remodeling and functional reorganisation of the trabecular system to occur and support the corrected occlusion (Clark, 1988). The support phase may be as important as the active phase, Twelve months may be necessary for bone maturation and stability (Nanda, 1998).

A retention period eventuates where nocturnal wear is usually sufhcient to stabilise the result. Interdigitation is of paramount importance for stability (McNamara, l9l5; Petrovic et a1.,1981; Owen, 1986; Petrovic, 1984; Clark,1982,1998; Pancherz, t981, 1985, 1997).If a new homeostatic state cannot be established return of the pretreatment condition could be expected (DeVincenzo,l99l; Clark, 1998)'

Figure 13 The sequence of trimming the upper molar covering to reduce overbite'

Lower molars are free to erupt initially. Later the upper molar occlusal coverage is removed to allow the molars to interdigitate (Clark, 1995) LITERATURE REVIEW 57

Moss (1980a,b) determined biting force applied to an incline plane produced effects on the dental arch, condylar head, muscle attachments and teeth remote from the teeth being moved. In an attempt to establish a new, more efficient masticatory system the stomatognathic system and soft tissues adapt. Following a few days of active therapy it may become painful to retract the mandible. This is more commonly seen with full-time appliance wear and is sometimes known as the "pterygoid response" (Clark 1988)'

Figure 14 The Pterygoid ResPonse

McNamara (1973) and Clark (1995)

Postured mandible

O initial conscious adaPtation to

n avoid traumatic occlusal contacts

Adaptive in function

(due to changed occlusal function)

& few days

Pain behind condyles (when appliance removed)

-conclusion from animal studies

(retraction of condyle gives compression of connective tissue

and blood vessels, thus ischaemia and pain)

o

New muscle pattern with altered muscle activity

(superior head of lateral pterygoid)

+

Difficullimpossible to retrude mandible

Thus more comfortable to wear appliance than leave it out.

!Sfficient time

o

Compensatory bone remodeling to adapt to altered function.

Possible glenoid fossa remodeling with condyles regaining original orientation in the glenoid fossa

Cell proliferation behind condyle. LITERATURE REVIEW 58

Table 3 Advantages of the Clark Twin Block

(Compiled from Clark 1982, 1988, 1995, 1997' 1998) Comfort Even with full-time wear. clinical management Decrease chair time. Easy to adjust and activate.

Robust; do not break easilY.

Aesthetic No visible anterior wires.

Arch development Sagittal and transverse (modify design).

Facial appearance Profile improves. Function Occlusal incline is the most natural of all functional mechanisms.

No restriction on function.

Less interference and mandible moves freely

(not restricted by bulky one piece appliance)'

Speech Not distorted since it does not restrict tongue, lips, and mandible. Compliance May even be fixed (temporarily/permanent). Asymmetry Asymmetrical activation corrects facial and dental

asymmetry in growing Patients.

Mandibular repositioning Rapid and stable (since worn full-time).

Vertical control Especially for deep bite or anterior openbite.

Age At any age for as long as patient is growing.

Less predictable and slower in older patients.

Safe Can be worn during most sports.

Efficient Rapid response compared to one piece appliances. Temporornandibularjoint Ifdisplaced condyle distal to articular disc, then recaptures disc.

Eliminate unfavourable occlusal contacts.

Integration with fixed appliances Simple; During the support phase.

Treatment Effects.

DeVincenzo and co-workers (1937) considered the wearing of an appliance full-time, working on the same principles as the Clark Twin Block with vertical guide planes to maintain the mandible forward with a single advancement. They concluded that possibly full-time wear for a few months followed by rest periods may in fact provide less dentoalveolar and more orthopaedic response. When compared to control patients DeVincenzo et al. (19S7) demonstrated a 31olo increase in overall mandibular length, over a 9.4 month period, comparable with the values reported in primate experiments (Trenouth, 1989). Mandibular length \ryas measured from articulare, but articulare is a LITERATURE REVIEW 59

superimposed point thus the contour of the cranial base will affect its position. Contouring of the glenoid fossa with treatment will also change the position of articulare (DeVincenzo, l99I; Mills, 1991). Anterior positioning of the mandible with the condyles out of the glenoid fossae, as suggested by Gianelly et al. (1983), DeVincenzo (1991) and Nelson et al. (1993), may provide an exaggerated increase in mandibular length. Transcranial radiographs and/or tomograms were taken on many of these treated patients and generally the condyles appeared seated in the fossae

(DeVincenzo et al, 1 987).

The Clark Twin Block is a tooth and tissue borne appliance (Clark, 1995,1997), which links the teeth together thus limiting individual tooth movement and maximising the orthopedic effect. We should not expect all patients to " grow their mandibles" (DeVincenzo et al., 7987; Clark, 1995).In humans, as many as 29Yo may have very little mandibular growth and primate experiments also report similar proportions, with no histological response when maintained in protrusive function (DeVincenzo et al', Ig87). This lack of response may be associated with endocrine levels. Petrovic and co- workers (1975, 1997) determined that somatomedin or large amounts of oestrogen, testosterone and/or cortisone have an attenuation effect on the growth of the mandibular condylar cartilage. Smaller amounts may have amplificatory effects on the growth of condylar cartilage (Petrovic et aL,l99l).

When Clark (1988, 1995), compared his results to Riolo et al. (1974) control values the following changes were noted: Ð Maxilla Decreased protrusion iÐ Mandible Accelerated increase in mandibular length

iiÐ ANB angle Decreased due to maxillary retraction and some mandibular

advancement

iv) Upper incisors Retracted v) Lower incisors Advanced (relative to A-Pogonion)

Procline during the active phase and upright during the support phase

vi) Interincisal angle Increased; retracted upper incisors and proclined lowers vii) Convexity Decreased; retracted A-point relative to facial plane

viii)Ramus height Increases LITERATURE REVIEW 60

ix) Facial height Increases in the support phase due to lower molar eruption

The changes of the active phase were maintained and stable 18 months out of retention'

Soft Tissue Effects

The facial soft tissues adjust to the Clark Twin Block very quickly and assist in the creation of a lip seal so as to allow effrcient mastication and deglutition (Clark, 1982)' A good lip seal is always achieved (Clark, 1995) without the conscious need for lip exercises. The facial appearance changes and a more relaxed lip posture is seen once full time wear is instigated. Cephalograms and laser scanning had been used by Moss et al. (1,993) and the rate of overjet reduction observed in assessing the efficiency of magnetic Twin Block appliances. These appliances worked twice as fast and produced twice the amount of change in the soft tissues (Moss et a1., 1993).

Morris et al. (1996,7998), demonstrated with cephalograms and facial laser scanning that the Clark Twin Block produced superior changes in the soft tissues, compared to the bionator and the Bass appliance. This was particularly seen with respect to advancement and lengthening of the lower lip, so as to move over and hold the upper incisors. The long-term stability of these results needs to be assessed. In addition, cooperation may play a large role in the individual variation seen in the soft tissue reactions detected, Though difficult to demonstrate, the analysis of " successfully treated" and compliant patients eliminates this effect to some degree. Unfortunately, this introduces a selection bias which is difhcult to eliminate without the examination of consecutively treated patients.

The Clark Twin Block appears to correct the Class II division 1 malocclusion by positional advancement of the mandible, retraction of the maxillary dentition and protrusion of the mandibular dentition, with an improvement in the soft tissues, including the profile. Morris et al. (7996) also noted greater than two millimetres more overjet reduction with the Clark Twin Block when compared to the bionator or the Bass appliance. LITERATURE REVIEW 61

The Fränkel Appliance

THE FRÄNKEL

+ --=l-f

Figure 15 Fränkel - frontal view

Figure l6 Fränkel - side view LITERATURE REVIEW 62

This essentially tissue borne exercise appliance (Graber, 1985; 1997a), developed in the 1950s and 60s, influences the maxilla and mandible to grow into their correct positions by retraining the muscles of mastication and the facial muscles to occupy new positions via acrylic shields. This establishes a new pattern in the central nervous system and thus overcomes poor postural performance of those muscles that determine the postural position of the mandible. Particularly the protractor group of muscles are exercised gradually (McNamara and Brudon, 1993) and by 2-3 millimetre advancements every 4- 5 months, the risk of muscle fatigue is reduced and the new forward position of the mandible gives renewed growth stimulation (Petrovic et al., 1981; Bishara and Ziaja, 19S9). Soft tissues may be well controlled with the Fränkel and an improvement in the patient's appearance is immediate. For instance, in the classical Class II division 1 patient with a lower lip trap, the lower lip pads unfurl the lower lip and displace it so as to sit in front ofthe upper incisors (Isaacson et al., 1990).

Treatment Effects Perillo et al. (1996) demonstrated mandibular growth due to the Fränkel of l-2 millimetres per year while other researchers show minimal, if any, increases in mandibular length (Robertson, 1983; Nelson et al., 1993). Creekmore and Radney (1933) stated no increase in length but did observe an increase in facial height due to vertical expression of the extra growth in the order of 1 millimetre. Nelson et al., (1993) also noted this increase in facial height, but attributed it to the vertical development of the mandibular molars.

Bishara and Ziaja (1939) attributed overjet correction to both orthopaedic (37%) and dental tipping (63%) effects. Retraction of maxillary incisors occurs (Creekmore and Radney, 1983; McNamara et al., 1985; Ghafari et al., 1998). Owen (1986) concludes that the Fränkel produces less maxillary retraction than headgear. Creekmore and Radney (1933) in addition to McNamaraet al. (1985) note a decrease in the forward movement of the upper molars, while the later, in addition to Bishara and Ziaia (1989) state there is also posterior maxillary vertical eruption.

Indirect tooth effects include guided eruption and lateral expansion especially in the maxilla due to the shields (McNamara and Brudon, 1993; Graber, 1997a). The curve of Spee also flattens through increase in the ramal length (Bajada, 1995)' LITERATURE REVIEW 63

Expansion in the maxilla is via bodily movement, especially as the teeth erupt, whereas in the mandibular arch there is more uprighting and less alveolar expansion. The removal of the buccinator forces may allow uprighting of lower molars as they erupt (Fränkel, in McNamara and Brudon, 1993). The Fränkel regulator can use the ability of the erupting tooth to act as a "matrix" for alveolar growth (Fränkel, 1974). Possibly most of the transverse development occurs during the mixed dentition (Stockfisch,

1 ees).

Most of the expansion occurs in the premolar and molar regions. A six millimetre expansion is an average transverse development in the maxilla, with a favourable reaction and good cooperation (Stockfisch, 1995). This is well beyond the average three millimetre increase in width across the posterior palate (Korn and Baumrind, 1990). McNamara and Brudon (1993) observed minimal post-retention arch dimensional changes.

Soft Tissue Effects

The shields expand the circumoral capsule and the lower lip posture is changed so as to facilitate a lip seal. Nielsen (19S4) notes that lip position is altered thus improving the soft tissue profile, but states that a majority of the patients show no change in facial convexity. Other authors report an improved soft tissue profile in all patients just based on the lip position. The operating shields force the muscles of the lips and cheeks to adopt a forced training effect (Fränkel, 1933) and in so doing ultimately alter their form. Upper incisor retraction does not corelate well with upper lip movement with the Fränkel (Battagel, 1990). Treatment may not result in coordinated movement of the upper incisor with the upper lip. There was, however, a correlation between the upper lip thickness and the lip position (Battagel, 1990) and with an increased upper lip length, less incisor and lip retraction occurred. LITERATURE REVIEW 64

INDICATIONS AND CONTRAINDICATIONS

One or Two Phase Treatment

With early treatment, the tissues of the craniofacial complex are more adaptive; as seen with animal experiments (McNamarc,1973), and cooperation is high (Kreit et a1.,1968; 'Weiss and Eiser, 1977). There is, however, a limited period of good cooperation available,

With two phase treatment, the first phase has limited goals. These are achieved in an active phase of six to twelve months, usually during the ages of 8 to 11 years. The intention is to treat patients to change their skeletodental relationships. This involves correction of molar distocclusion, improvement of overbite and overjet relations, incisor interrelations and thus the soft tissue profile. Usually the second phase of " finishing" treatment is necessary to detail the occlusion, during the ages of 12 to 15 years. The second phase of treatment is simplified by the first phase. Two phase treatment occurs in25Yo of treated children (Gottlieb et al., 1991). This is the equivalent of a third of all children (Gianelly, 1995).

Gianelly (1995) believes by starting treatment in the late mixed dentition, greater than 90Yo of our growing patients can be treated with one phase treatment. Livieratos and Johnston (1995) state that at the completion of treatment in the two non-extraction Class II groups they studied, the bionator / edgewise regime compared to the single stage edgewise alternative, were basically identical. Thus for the central 75Yo of patients no obvious measurable benefits were detected in the use of this functional appliance. Fixed appliances would probably provide less stimulation for forward growth of soft tissue pogonion (Koch et al., 1979). Pancherz (1997) treated 10-11 year olds for six months with a Herbst appliance and noted an average of 3.2 millimetres of mandibular growth. Wieslander (1984), also with the Herbst appliance on 8-9 year olds, recorded an average of 3.4 millimetres mandibular growth over a five month period. This response appears not to be age dependent for as long as the individual is growing. The profile convexity decreased after this phase of treatment, but long retention periods were required to prevent overjet reappearing. The possibility exists that "true growth" was not recorded and forward mandibular posturing may have been sustained for some time after appliance removal. The method of evaluation is obviously crucial. LITERATURE REVIEV/ 65

Advantages and Disadvantages of Functional Appliances

1. ADVANTAGE,S OF FUNCTIONAL APPLIANCES Ð Ideal for uncrowded Class II division 1 patients and can be used in the mixed dentition. b) Economic delivery of care to a large number of patients, as seen in Europe (Clark, ree7). c) Fixed appliance treatment time decreased (Tulloch et al., 1998). d) Less breakages than when treating with fixed appliances' e) Chair time decreased compared to full f,rxed appliance treatment, if a second phase of treatment is not required. Ð Oral hygiene; Decreased decalcification (Graber, 1985) and decayed-missing-filled scores. g) Better cooperation (King et a1.,1990). However a finite amount of cooperation may be available. Yet Tulloch et a1., (1998) determined that a failure to respond favourably could not be explained by lack of cooperation alone' h) Immediate prof,rle improvement (Isaacson et al', 1990). i) In general, functional appliances prevent injury; for instance, there is a decreased possibility of root resorption (Graber, 1985; King et al',1990). j) Intercept dysfunction; for instance, a lower lip trap or a hyperactive mentalis (Graber, 1985; King et al., 1990).

k) Intercept mouthbreathing.

l) Psychological advantage, since after treatment no teasing occurs and self-confidence is gained (Tung eI a1.,1998). King and co-workers (1990) note that patients with milder forms of facial disfigurement, like some malocclusions, suffer more psychological stress because they have not developed coping mechanisms against the erratic, inconsistent teasing and ridicule.

m) Possible improved prognosis, due to increased aesthetics, stability and decreased extractions and treatment time (King et al., 1990).

n) Increased vertical control ofdeepbites. o) Allows monitoring for the appropriate time to start fixed appliance therapy.

p) Enhances "mandibular growth" (Graber, 1985; DeVincenzo, 1991; V/indmiller, 1993; Lund and Sandler, 1998) LITERATURE REVIEW 66

q) May decrease the need for orthognathic surgery (Tulloch et a1., 1998). r) Corrects aberrant mandibular growth (Ayoub and Mostafa,1992). For instance, in cases with circulatory interruption (Petrovic et aI., 1981) and asymmetries associated with hemifacial microsomia (Harvold and Vargervik, l97I).

2. DISADVANTAGES OF FUNCTIONAL APPLIANCES.

a) Additional cost of functional appliances. Precise detailing of the occlusion is not possible with functional appliances (Isaacson et al., 1990; King et al., 1990). The interincisal angle cannot be corrected, thus excellent results require fixed appliances. In limited situations, however, a functional appliance will not be followed by fixed appliances for final occlusal detailing.

b) Compliance loss; cooperation decreases with treatment time (Isaacson et al., 1990; King et al., 1990).

c) Crowded cases cannot be easily managed with a functional appliance.

d) Abnormal function may be seen with some functional appliances. This may be apparent with activators and Fränkel appliances. Patients may be unable to eat and speak clearly with them for quite some period of time (King et al., 1990). Some patients adapt better than others.

e) Possible abnormal condylar growth (hypoplasia) and even possible pathology (King et al., 1990). For instance, osteoarthritis or rheumatoid arthritis.

f) Often increased treatment time is seen with the use of functional appliance (Tulloch et al., 1998). There is often an increased need for retention so as to minimise relapse prior to entering the second phase of treatment (Clark, 1998).

g) Some tissue damage may occur, including hyperplastic gingivitis, damage to the periodontium, gingival recession and possibly even decalcification and caries. Root resorption may be detected if excessive extraoral forces are applied, but this is also true of fixed appliances.

h) Limited in the non-growing and the response is variable post-puberty (Bishara andZiaja,1989; Isaacson et al., 1990).

i) Initial patient discomfort, but this is also associated with fixed appliances.

j) Some functional appliances may fail in allergic patients with airway problems.

k) May encounter lower incisor proclination. LITERATURE REVIEV/ 61

These risks are common to most orthodontic appliances anda review of the literature suggests that there are few published works on the risks of caries and decalcification associated with functional appliances. There is the belief that most are removable, thus oral hygiene is improved and the risk is markedly reduced.

Tulloch and co-workers' (1997a) findings support the rationale that different appliances should be used to treat specific Class II problems. However, due to the wide variation of individual responses, we are unable to predict which, if any children will respond favourably. Some patients may grow favourably (Tulloch et al., 1997b) irrespective of the appliance employed.

Bishara andZiaja (1989) state that appliance selection should be based on differential diagnosis and not because a particular appliance is considered to have a more marked effect on mandibular growth. A functional appliance is merely a "tool" and the practitioner must recognise the advantages and limitations associated with it, so as to most benefit from its potential.

There are a number of influences which modifu the servosystem which controls growth of the mandibular condylar cartilage and lengthening of the mandible (Lavergne and Petrovic, 1983).

These include:

o the type of appliance and its modifications.

o tissue response and rate offibroblast turnover.

o compliance.

. morphologic pattern.

o growth - the amount, direction and timing of residual growth present.

o neuromuscularpatterns.

o functionaldisplacements.

o dentoalveolar compensations (Graber, 1985). LITERATURE REVIEV/ 68

2.5. CONCLUSION

Although orthodontists would enjoy the comfort of consistent responses with the application of a specihc functional appliance, a specific mode of growth may well alter this treatment response (Carels and van der Linden, 1987). A wide variation in response to similar appliances has been detected (Vargervik and Harvold, 1985; Tulloch et al., lg97b, 1993). In addition variation in the amount of protrusion within and between appliances may elicit different results (Op Heij et a1.,1989). A multifactorial situation exists with respect to Class II skeletal correction. In addition to ethical considerations, limitations exist in our research models and designs which are difficult to overcome (Isaacson et al., 1990). Patients with, for example, divergent skeletal features should be treated similarly and the results analysed to determine the soft tissue effect of a certain procedure on that subgroup of individuals. However, a review of the current literature reveals few publications on stratified cornparative studies.

Although several works have discussed the treatment effects of the activator with headgear, the Fränkel and the Clark Twin Block separately in the literature, few, if any direct comparisons of these appliances have been reported, particularly when addressing soft tissue effects. Thus comparing these treatment modalities is warranted.

Even following this plethora of research on functional appliances it appears that further well conducted studies are necessary to determine the precise nature of the effects we provide.

The ideal study is difficult and costly to organise. It would involve a double-blind, randomised, prospective study on humans where there is standardisation of the observation period, the appliance used, the design and fabrication of the appliance and the degree of protrusion incorporated. In addition, operator technique and patient compliance needs to be accurately assessed. Matched controls are essential so as to be capable of accurately assessing changes, which occur. Few authors have expressed the ability to conduct a study approaching this ideal (Tulloch et al., 1997a,1997b,1998).

The suggestion that face type and specific growth patterns should determine the choice of functional appliance automatically means either large sample sizes to permit complete randomisation or selection bias presuming a particular appliance response. M¡.rsRrels & Mpruons 69

3. MATERIALS AND METHODS

3.1. SELECTION OF SAMPLE

The sample for this research project comprised orthodontic records from three private specialist orthodontic practices in Adelaide, South Australia.

All the activators in the sample were used with headgear and were obtained from the orthodontic rooms of Dr. Colin Twelftree. These were all consecutively started activators, with headgear being usually added on the appointment following insertion. These cases were all treated to completion without subject attrition.

The Clark twin blocks were selected from the records of Dr. Guy Burnett. They were constructed as described by Clark (1988, 1995). No intraoral or extraoral traction was used in the selected sample, and an incline plane of approximately 70" was constructed in each appliance.

The Fränkel appliances were all obtained from the orthodontic practice of Dr. Steve Bajada. Both Fränkel I and Fränkel II appliances were incorporated in the sample. The criteria determining selection of the Fränkel I appliance were very proclined maxillary incisors. The Fränkel II appliance \À/as selected by the operator if the upper incisors were in a reasonably good position, or not overly proclined, such that the palatal wire held them there. MATERIALS & MBTHO¡S 7O

Criteria for sample selection:

1. Diagnosis by the operator as a skeletal Class II, division 1 malocclusion.

2. Assessment of at least one Class II molar relationship

3. A minimum overjet of 4mm

4. No prior serial extractions, nor any concurrent orthodontic treatment during the course of functional therapy.

5. The absence of observable major dental and craniofacial deformity, as determined by the medical history.

'Well 6. documented operator treatment records, from the time of diagnosis to at least the end of functional appliance therapy.

a). Pretreatment radiographs taken within 90 days before the start of active treatment.

b). End of treatment radiographs taken within 90 days after discontinuation of "active" functional therapy, or prior to the " retention" period.

7 . All three operators believed they employed aî average treatment time of one year, followed by a retention period of variable lengths of time. The Clark twin block and the Fränkel appliances are employed fulI time, after an initial adjustment period, while the activator with headgear was worn for a few hours in the evening and during sleep.

8. All individuals included in the sample were of Caucasian origin. MATERIALS & METHODS 7I

The sample consisted of 94 patients between the ages of 8.0 and l4.l years. This included approximately equal numbers of males and females, that is, 49 males and 45 females. Each of the three functional appliance groups were subdivided according to sex as shown in Table 4.

Table 4 Breakdown of the functional appliance sample numbers and ages

Breakdown of functional appliance sample numbers' Sample numbers Males Females TOTAL

Activators l7 18 35

Clark Twin Blocks I7 13 30

Fränkels 15 t4 29

TOTAL 49 45 94

Breakdown of the sample ages.

Mean ages Males Females TOTAL (plus range)

Activators I 1.2 years 1 1.0 years 11.1 (8.3 - 14.s)

Clark Twin Blocks 10.7 years 10.5 years 10.6 (8.3 - 13.e)

Fränkels 10.9 years 10.8 years 10.8 (8.0 - 14.7) MATERIALS & METSONS 72

3.2. RADIOGRAPHY

Radiographs were produced by a number of different radiographic premises in Adelaide resulting in standardisation difficulty.

Most of the pre-treatment and post-treatment radiographs were obtained from within the same radiographic institution. Howevet, nine were not ( three activator, hve Clark Twin Block and one of the Fränkel). The magnification has been determined and appropriate correction made.

Where metric rulers were used and placed in the mid-sagittal plane, the magnification was easily determined and allowance made for the variation in the cephalometric radiographs.

Twenty-four radiographs had no metric ruler displayed. In these instances an average magnihcation was employed according to the mean known magnification of the institution at which the radiograph was taken.

Table 5 Gephalometric radiographs with visible metric rulers

Visibitity of ruler's Metric ruler visible No metric ruler on cephalograms visible

Activators 70 0

Clark Twin Blocks 4l t9

Fränkels 53 5 MATERIALS & MBTUOOS 73

Table 6 Facilities from which cephalometric radiographs were obtained

Radiographic Number Number with Mean metric ruler not "/omagnifitcation facility of cephalograms visible

R. MacDonald &, 108 0 8.3 % Associates

Jones & Partners 28 18 7.3 %

(13 CTB; s FR)

Benson & Partners ZJ 4 13.0 Yo (CTB's)

Miller & Moore 22 0 8.5 %

Perretts, Harrison & 5 2

Partners (crB s) rl.6%

Adelaide 1 0 7.5 Yo

Dental Hospital

Murray 1 0 7.0 %

Bridge Hospital MATERIALS & METHODS 74

To determine the average magnification of the radiographs the following formula was used:

Lc Percentage magnification : I x 100 LI )

where, L. is the actual length of ruler image on cephalogram and L, is the inferred original length of metric ruler according to the scale seen on the cephalogram'

Table 7 Mean magnifications of cephalometric radiographs

Mean Pre-treatment Post-treatment Mean Magnification cephalograms cephalograms Tomagnification (%)

Activators 9.7 % 9.8 % 9.8 %

Clark Twin Blocks 8.6 % 8.6 % 8.6 %

Fränkels 8.r % 8.t % 8.1Yo

3.3. TRAGING TECHNIQUE

The tracings \ /ere all performed in a standardised, suitably darkened room, with quiet surroundings. A viewing screen was used, in addition to black overexposed radiographic films of varying dimensions to enable reduction of glare and restrict light intensity to a defined area. Optimum lighting and contrast conditions were used to facilitate landmark identification. Houston (1983) describes inaccurate landmark identification as one source of random errors, which are randomly provided as part of MATERIALS & MgrgOPS 75

the sample data. A single operator was used for tracing, landmark identihcation, and digitising so as to minimise the introduction of systematic errors (Houston, 1983).

The tracing technique involved attaching the cephalogram facing to the right to the viewing screen with adhesive tape, fixing a sheet of high quality matte acetate orthodontic tracing paper over the cephalogram and using a 0.5mm '28' mechanical pencil to trace the radiograph.

Each individual patient tracing was completed at a single sitting. This was employed to reduce some systemic errors which, may be introduced by the experimental technique (Houston, 1983). Systematic errors were also minimised by tracing cases in a random order, thus eliminating any knowledge of which group the records belonged (Houston,

I e83).

At a later time and in a random fashion each radiographic tracing was later rechecked to minimise any single gross errors (Stabrun and Danielsen, 1982).

3.4. SUPERIMPOSITION TECHNIQUE

The superimposition technique involved the use of structures suggested by Björk and Skieller (19S3). The anatomic structures involved included the anterior contour of sella turcica, planum sphenoidale, the anterior outline of the middle cranial fossa, the inner surface of the frontal bone, the contours of the cribriform plate and the small bony trab eculae, particularly the ethmoid trabeculations.

Five fiducial markers were spread out and drawn on each pre-treatment radiograph. The radiograph and the acetate were fixed to the viewing screen. The fiducial markers (Tr) were then traced onto the pre-treatment acetate with the pre-treatment tracing. This enables correct, reliable and reproducible repositioning of the acetate back onto the cephalogram at any later time. The pre-treatment radiograph and tracing were then removed from the viewing screen. MATERIALS & METHODS 76

Figure 17 Structures suggested by Björk and Skieller (f 9æ) for Granial Base Superimposition.

4

( 5 J 6

\

1 . anterior contour of sella turcica

2. planum sphenoidale

3. anterior outline of the middle cranial fossa

4. inner surface of the frontal bone

5. contours of the cribriform plate

6. small bony trabeculae, particularly the ethmoid trabeculations MRTSRIRT.S & METHODS 77

The post-treatment cephalogram was then marked with five well spaced fiducial markers and fixed to the same viewing screen with adhesive tape. The second acetate was then overlaid and also fixed to the screen, in the same manner. This second lot of fiducial markers (Tz) were then traced onto the post-treatment acetate, in addition to the usual post-treatment tracing. The acetate and the post-treatment cephalogram were then both removed from the screen.

The two radiographs were then overlaid according to the superimposition technique described by Björk and Skieller (1983), They were then hxed to the viewing screen and the fiducial markers from the pre-treatment radiograph (Tr) were traced onto the post- treatment acetate tracing and labelled appropriately (ie. as Tr). The radiographs and acetate were then removed from the viewing screen.

The patients name, the date and the institution at which the radiographs were taken, were marked on the appropriate acetates.

The two acetate tracings could now be superimposed with the use of the relevant fiducial markers.

The sella-nasion line minus 7 degrees from the pre-treatment tracing was transferred to the post-treatment tracing. This reference line also formed the X-axis on the post- treatment tracing.

The marks on both of the actual cephalograms were erased

This method allowed the soft tissue profile changes to be determined in relation to the cranial base.

A line through sella-nasion minus seven degrees was used as the X-axis (Burstone et al, 1978; Lundström and Lundström, 1992; Proff,rt, 1993; Tulloch et al., 1997a ), thus the orientation of the hlm was better controlled. Obviously, the slope of sella-nasion in MATERIALS & METHODS 78

relation to other cranial structures and natural head posture would be expected to show considerable variation (Moorrees and Kean, 1958; Marcotte, 1981). Natural head position would be the ideal option (Lundström and Lundström, 1992) so as to analyse our radiographs in relation to the true vertical and horizontal parameters. The limitations of a retrospective study ensured that natural head posture was unable to be determined with certainty, consequently, the reference plane selected was as optimal as possible, that is, the sella-nasion line minus 7 degrees'

A vertical line, representing the Y-axis, running through sella and perpendicular to the X-axis of SN-7'was also used ( Sidhu et al., 1995;Pancherz,1,997;IIIing et aI,1998; Morris et al., 1998).

Even though Ricketts and co-workers (1976) have reported Frankfort Horizontal to be as reproducible as sella-nasion, there are a number of contrary studies (Salzmann, 1960: Baumrind and F rantz, 197 | a, I97 lb).

In addition to the major study of 188 tracings (on 94 patients), a random sample of 20 radiographs were retraced, and redigitised to determine the error of the method.

3.5. COMPUTERISEDCEPHALOMETRICSANDDIGITISING

Professor Tasman Brown of The University of Adelaide, Department of Dentistry, developed and modif,red the system used in this research. It consisted of digitising the radiographs on a Hewlett Packard 9874A digitiser using an Apple IIGS microcomputer.

The following digitising sequence was used:

1. Digitiser screen cleaned with ethyl alcohol.

2" The pre-treatment tracing was taped to the digitising screen.

3. The digitising programme was loaded onto the computer. MerBRtRr-s & MBrHoos 79

4. The patient's name and details were recorded.

5. Axis alignment was recorded, with sella-nasion line points and a point along the SN-7 line, so as to define the X-axis.

6. Landmarks were digitised in the specific numerical order specified (Figure 18).

7. The millimetre ruler on the radiograph was also digitised and the actual length was recorded so as to enable the magnification to be calculated. All linear measurements were compensated for magnification.

8. Superimposition of the actual tracing over the digitised tracing (printed on a Hewlett Packard 9872A plotter) allowed determination of reliability of all landmarks being accurately digitised.

9. This procedure was repeated for each new tracing.

3.6. REFERENCE PO¡NTS

Whenever possible, midsagittal plane points were selected to keep the magnification factor constant. This is assuming the ear rod axis was pe{pendicular to the midsagittal plane and there was no anatomic variation in the position of the external auditory meati in the subjects present in this sample (Houston, 1983). MATERIALS & MBTUOIS 80

Figure 18. The Gephalometric Landmarks

+ +

2 '1" + 23

4 2l Ja

8 7 5 25 11

l8 6 1 3I + 15 6

aa JJ MATERIALS & METHODS 81

Tabte I Hard tissue cephalometric landmarks and abbreviations

Number Hard Tissue Landmarks Abbreviation

1 Sella S

2 Nasion N

3 Orbitale Or

4 Porion Po

5 A point A

6 B point B

7 Anterior nasal spine ANS I Posterior nasal spine PNS I Upper incisal edge U1E

10 Upper incisal apex U1A

11 Upper molar distal cusp reference point UM

12 Lower incisor edge L1E

13 Lower incisor apex L1A

14 Lower molar distal cusp reference point LM

15 Pogonion Pog

16 Gnathion Gn

17 Menton Me

18 Gonion Go

19 Articulare Ar

20 Condylion Co

21 Pterygo-maxillary fissure PTM

22 Basion Ba M¿,reRIers & Msruons 82

Table 9 Soft tissue cephalometric landmarks and abbreviations

Number Soft Tissue Landmarks Abbreviation

23 Soft tissue nasion STN

24 Nasal tip N tip

25 Subnasale Sn

26 Sulcus superius Ss

27 Labrale superius Ls

28 Upper lip lowest point ULL

29 Lower lip highest point LLH

30 Labrale inferius L

31 Sulcus inferius Si

32 Soft tissue pogonion ST Pog

33 Soft tissue menton ST Me

Detailed def,rnitions of cephalometric landmarks and variables are contained within the Appendix (8.1, 8.2).

3.7. THE VARIABLES

The cephalometric landmarks were used to determine 53 variables. These were 32 hard tissue and 2l soft tissue variables. The hard tissue variables consisted of 13 angular and 17 linear measures. In addition there were two ratios calculated for upper face height to lower face height, and also for posterior face height to anterior face height.

The soft tissue cephalometric variables comprised four angular, 16 linear measurements and aratio determining the soft tissue lower face height percentage. MRrBRrels & MerHoos 83

Table 10 Hard tissue cephalometric variables and abbreviations

Number Hard tissue variable Abbreviation

1 sella-nasion to Frankfort horizontal SN-FH f) 2 SNA angle SNA f)

3 maxillary plane to sella-nasion MaxPl-SN (")

4 maxillary length Co-A (mm)

5 upper incisor to sella-nasion u1-sN (')

6 upper incisor to NA angle u1-NA f)

7 upper incisor to NA distance U1-NA (mm)

8 upper incisor to maxillary plane angle U1-MaxPl (') I inter-incisal angle u1-11 f)

10 lower occlusal plane LOP f)

11 ANB angle ANB f) 12 lower incisor to NB angle L1-NB f)

13 lower incisor to NB distance L1-NB (mm)

14 lower incisor to mandibular plane angle |MPA f)

15 lower incisor to mandibular plane distance L1-MP (mm)

l6 SNB angle SNB (")

17 true mandibular length Co-Gn (mm)

18 mandibular length Ar-Gn (mm)

19 true ramus height Co-Go (mm)

20 ramus height Ar-Go (mm)

21 upper anterior face height UFH (mm)

22 lower anterior face height LFH (mm)

23 anterior face height ratio UFH:LFH

24 total anterior face height N-Me (mm)

25 posterior face height S-Go (mm)

26 posterior to anterior face height ratio PFH:AFH 27 Frankfort horizontal to mandibular plane angle FMA f) 28 A-point to Sella vertical A-S vert (mm)

29 B-point to Sella vertical B-S vert (mm)

30 pogonion to Sella vertical Pog-S vert (mm)

31 overjet OJ (mm)

32 overbite OB (mm) MRTBRTRIS & METHODS 84

Table 11 Soft tissue cephalometric variables and abbreviations

Number Soft tissue variable Abbreviation

33 Facial convexity F. conv. f)

34 Nasolabial angle N-L ang. f)

35 Labiomental fold L-M fold (')

36 Modified harmony angle H angle C)

37 Upper lip thickness Ls-A (mm)

38 Lower lip thickness Li-B (mm)

39 Soft tissue total face height ST TFH (mm)

40 Soft tissue upper face height ST UFH (mm)

41 Soft tissue lower face height ST LFH (mm)

42 Soft tissue lower face percentage ST LFH%

43 Upper lip (Ls) to E line Ls-E line (mm)

44 Lower lip (Li) to E line Li- E line (mm)

45 Upper lip length ULL (mm)

46 Lower lip length LLL (mm)

47 Soft tissue pogonion- Soft tissue Nasion ST Pog-ST N (mm)

48 Subnasale - Sella vertical Sn-S vert (mm)

49 Sulcus superius- Sella vertical Ss-S vert (mm)

50 Labrale superius to Sella vertical Ls-S vert (mm)

51 Labrale inferius to Sella vertical Li-S vert (mm)

52 Sulcus inferius to Sella vertical Si-S vert (mm)

53 Soft tissue pogonion to Sella vertical ST Pog-S vert (mm)

3.8. STATISTICAL ANALYSES

The Apple IIGS disk operating system (PRODOS) format data was converted to an IBM Microsoft'Windows 95 format using a Macintosh Power PC computer, and then converted to an IBM platform Microsoft Excel spreadsheet format for basic descriptive statistical analysis of each variable. For further statistical analysis the Microsoft Excel spreadsheet was transferred into an SPSSX 6.1 statistics package (SPSS Inc.) using a Macintosh Power PC computer. Mer¡RtRI-s & M¡ruo¡s 85

Overbite and overjet were calculated using the Microsoft Excel spreadsheet program which processed ra\ry x and y coordinate data. The Apple IIGS cephalometric program was unable to determine these particular variables from the data available.

The IBM Microsoft Excel spreadsheet was employed to calculate basic descriptive statistics, including means, standard deviations and z-scores for each of the three functional appliance groups, and for males and females separately. Paired and unpaired t-tests were also performed to provide comparisons within and between groups.

Z-scores were determined to identify any outlying values. These were checked against the original datato ensure they were an expression of normal variation (Houston, 1983)'

Z-scores were calculated as:

(x it z where x : aÍL individual observed value of a given variable sd

Paired t-tests were used to compare pre-treatment and post-treatment mean values, while unpaired t-tests were used to compare mean values between the males and females. Prior to carrying out unpaired t-tests, variances of samples were compared using variance ratio tests (F-tests).

F-tests were calculated as follows:

t2 ,ç4, F : using the standard deviation (sfl for each subgroup, such that F > 1 +sa't

For unpaired t tests with statistically equivalent variances, the t values were calculated using the standard t-test method as follows: -\- t: S, lln,+lln,

(nr-I)sdr2 +(nr-l)sd where Jr, = nr+nr-2 MATERIALS & MSTHOPS 86

and x: sample mean

n: sample size

sd: standard deviation of sample

degrees of freedom : nl + n2 - 2

If F- values were significant, a modified t-test was used (Sokal & Rohlf, 1981)

xt-xz t- 22 .ç, .ç- r,4-r nt n2

Scattergrams were generated to demonstrate any relationship between treatment time and the variables measured. In addition they were produced to examine possible associations between each variable and subject age. Correlation coefftcients, r, were also calculated to quantiff the strength of the association between pairs of variables (Sokal and Rohlf, 1981).

The SPSSX statistics package was employed to determine the normality of the distributions, via skewness and kurtosis estimations and the Kolmogorov-Smirnov test statistic, for each variable. Analysis of variance (ANOVA) was also performed. The three functional appliance groups were analysed initially with a two-way ANOVA. The two-way ANOVAS, with groups and sex as factors, were performed on the pre- treatment variables, the post-treatment variables, and on the differences between pre- and post-treatment for each variable.

Where significant results were obtained, a further one-way analysis of variance and Student-Newman-Keuls post-hoc test were used to determine which groups differed significantly, following a similar approach described by Illing et al. (1998) and Monis et al. (1998).

Given that the sample size in each of the study groups (activator, Clark Twin Block, Fränkel ) range from29 to 35, the study is estimated to have a power of 80% - 85% of detecting a one standard deviation difference in the variables studied at the five percent level (InStat2.0I). MATERIALS & MNTUOOS 87

3.9. ERRORS OF THE METHOD

In determining the error of the method, 20 cephalograms were randomly selected by the operator and retraced. Thus each of these 20 radiographs was traced twice by the same operator and then digitised. The second tracings were performed at least two months later, with the patient details erased, so as to eliminate the effect of memory bias (Stirrups, 1993).

Errors in a study such as this may be introduced by a number of sources. These include the obvious cephalometric radiographic technique, magnification, precision of landmark identification, tracing and superimposition technique, digitisation and also the errors incorporated in the measurement by the computerised equipment.

With positioning of the head in the cephalostat, head orientation may vaty, introducing random errors which may affect the reproducibility of soft tissue points (Burstone, 1967; Hillesund et al., 1978). Reproducibility is obviously dependent on the care of the operator tracing, measuring, and digitising the records, in addition to, the quality of the records (Houston, 1983). Variation in the film density and sharpness can lead to random errors (Houston, 1933). Halse and Hedin (1978) contest this importance of quality for landmark identification.

In addition, areas of error may often be related to the problems associated with growth andlor treatment. These may alter the anatomical landmarks routinely used by many researchers for superimpo sitions.

The error study data were compared to the corresponding original data as follows.

For each variable, calculations were made of:

diff difference between values for first and second determinations

mean diff mean of differences between paired values from the two determinations MRrsRrRLs & Msruoos 88

sd diff standard deviation of paired differences between the two determinations

I¿in' sum of squared differences of paired values between the two determinations

Se Dahlberg statistic

E(var) Error variance; the variance due to measurement error expressed as a percentage ofthe total observed variance,

: Se2 E(var) f7 x 100 (ie. expressed as apercentage)

where Se2 : variance due to measurement error, based on the Dahlberg statistic, Se

Sou,2: observed variance of sample as determined by calculating the weighted average of the original pre- and post-treatment variances for the total sample. This value would include true sample variance and variance due to measurement error.

SE mean diff standard error of the mean difference

t value of / as derived from Student's t-test (described below)

To determine systematic error, the use of paired /-tests between the two measurements in the error study allowed the determination of any significant differences (at the p<0.05 level).

The t value was calculated as: t: meandiff SE meandiff

with n- I degrees of freedom, where n: number of double determinations MernRrRr,s & MBrHoos 89

To determine the magnitude of the random error of landmark location the Dahlberg statistic (Dahlberg, 1940) was calculated as:

-2Ldiff Se: where n: number of double determinations 2n

The reliability was calculated for each landmark in the x-axis and y-axis. In addition reliability was calculated for each variable so as to determine the total error of the method.

Reliability was calculated as follows:

Reliability: 100 - E(var) (ie. expressed as a percentage)

Reliability coeffrcients greater thang}Yo were considered to be acceptable while values less than 80olo rendered the measurement doubtful (Buschang et a1.,1987). RESULTS 90

4. RESULTS

As a f,rrst step in data analysis, the distributions of variables were tested for normality.

Kolmogorov-Smirnov (Lilliefors) test statistics were calculated for all variables, with a recommended 0.2 significance level. For confirmation, normal and detrended normal, probability plots were also examined for each variable. Some variables exhibited one to a few extreme values but these plots failed to reveal any extreme or consistent non- normality in the data. Overall, the cephalometric data appeared to be normally distributed.

Skewness and kurtosis were also estimated for each variable in an attempt to further examine the sample distributions. Tables of critical values (Zar, 1984), and two-tailed tests of skewness were employed. Even though kurtosis was determined, limitations exist when the sample size is less than 1000 (Zar, 1984). These estimates of skewness and kurtosis showed no clear trends of a significant lack of normality in the distribution of the 53 variables. The variables could therefore be described adequately in terms of means and standard deviations.

The results of the statistical analyses of this investigation are presented in tabular form. Throughout the Results section, tables have been divided into hard and soft tissue variables. The linear measurements are all calculated in millimetres (mm), while the angles are all in degrees (').

4.1 THE ERROR STUDY

Section 4.1 presents the error study. Landmark identification error was estimated via double determinations and its analysis. The error in the x-axis and the y-axis, with respect to SN-7o, was considered for each landmark. In addition the error study involved an analysis of the variables. Random and systematic error were determined. The Dahlberg statistic (1940) was calculated for each landmark and for each variable" The observed variance was determined with the use of a weighted, aveÍage standard deviation for the entire sample. The weighting was performed, with males and females RESULTS 9l

combined, according to the three functional appliances. The error variance ratio, E(var), was also computed and the coeffrcient of reliability was also calculated (Midtgård, 1974). The level of statistical significance throughout this investigation was set at the p<0.05 level (*), however variables significant at the p<0.01 and the p<0.001 have also been appropriately denoted, (**) ot (***) respectively.

Table 12 Error Study: Results for double determinations of landmark identification. Hard Tissue Landmarks

Landmark mean diff sd diff Sumdiffsq Se E(var) Reliability T prob. Signif

S x-axis 0.33 o.82 14.85 0.61 0.2 99.8 0.086

y-axrs 0.53 1.38 41.82 1.02 2.9 97.1 0.1 04

NX 0.48 1.37 40.24 1.00 0.5 99.5 0.1 30

v 0.41 1.30 35.41 0.94 2.3 97.7 0.170 Orx 0.87 1.79 76.31 1.38 0.9 99.1 0.042

v 0.15 1.34 34.61 0.93 2.3 97.7 0.621 Pox 0.18 1.25 30.45 o.87 0.4 99.7 o.521

v 0.03 1.66 52.63 1.15 3.2 96.8 0.947 AX o.21 1.22 29.03 0.85 0.3 99.7 0.449

v -0.44 1.23 32.66 0.90 2.1 98.0 o.126 Bx 0.30 1.14 26.66 0.82 0.3 99.7 o.248

v 0.65 1.62 58.07 1.20 2.7 97.3 0.087

ANS X 0.89 1.57 62.70 1.25 o.7 99.3 0.020

v o.47 1.70 59.48 1.22 3.6 96.4 0.228

PNS X 0.19 1.32 33.81 0.92 o.4 99.6 0.528

v 0.20 1.05 21.75 0.74 1.5 98.5 0.408 U1E x 0.36 1.29 34.24 0.93 0.4 99.6 0.221

v -0.08 0.83 13.28 0.58 o.7 99.3 0.688 U1A x 0.34 1.28 33.53 0.92 o.4 99.6 0.244

v 0.04 1.35 34.44 0.93 2.2 97.8 0.905

UMX -0.10 1.70 55.1 6 1.17 0.6 99.4 0.797

v 0.60 3.81 283.46 2.66 20.3 79.7 0.489 L1E x 0.26 1.25 30.88 0.88 0.4 99.7 0.366

v o.o2 0.66 8.38 0.46 0.5 99.5 0.889 L1A x 0.30 1.32 34.93 0.93 o.4 99.6 0.323

v o.37 0.83 15.75 0.63 0.9 99.1 0.063 RESULTS 92

Table 12 continued

Landmark mean diff sd diff Sumdiffsq Se E(var) Reliability T prob Signif

LMx o.44 1.02 23.60 0.77 0.3 99.7 0.066

v 0.31 0.77 13.13 0.57 0.9 99.1 0.091

Pog X 0.28 1.30 33.76 0.92 o.4 99.7 0.357

v -0.45 1.23 32.85 0.91 1.5 98.5 0.1 15

Gn X 0.37 1.59 50.81 1.13 0.5 99.5 0.306

v 0.07 1.01 19.45 0.70 0.9 99.1 o.743

Me X 1.11 2.O4 103.56 1.61 1.1 98.9 0.025

v -0.13 0.45 4.12 0.32 0.2 99.8 0.210

Go X 0.06 0.80 12.17 0.55 0.1 99.9 0.722

v -0.18 0.66 8.77 o.47 0.6 99.4 o.246

Ar X 0.11 0.75 10.98 o.52 0.1 99.9 0.534

v 0.35 1.05 23.18 0.76 1.5 98.5 0.1 53

Co X -0.11 0.93 16.66 0.65 o.2 99.8 0.593

v 0.51 1.35 40.01 1.00 2.7 97.4 0.111

PTM X o.77 0.97 29.57 0.86 0.3 99.7 0.002

v o.74 1.18 37.68 0.97 2.6 97.5 0.011

Ba X 0.o2 1.O4 20.71 0.72 0.2 99.8 0.928

'1.3 v 0.16 1.13 24.86 0.79 98.7 0.534

(*) significant at p<0.05

(* *) significant at p<0.01

(* * {.) significant at p<0.001

Reliability was greater than 96 percent for all landmarks apart for the upper molar distal cusp reference point. In the y-axis, the upper molar point had reliability of less than 80 percent.

Five landmarks were statistically significant for their systematic errors. These included orbitale (x-axis), anterior nasal spine (x-axis), menton (x-axis), pterygomaxillary fissure (x-axis and y-axis) and soft tissue menton (x-axis). Most systematic effor was in the x- axis.

In observing the individual treatment changes, an eTror in landmark identification of Co andlor Gn was obviously encountered (Appendix 8.7; patient 9 in the Fränkel group)" Rasulrs 93

Table l3 Error Study : Results for double determinations of landmark identification. Soft tissue landmarks

Landmark mean diff sd diff Sumdiffsq Se E(var) Reliability T prob. Signif.

STN X 0.64 1.54 52.98 I .15 0.6 99.4 0.079

v 0.29 1.80 63.30 1.26 3.9 96.1 0.486 Ntip x 0.56 1.41 44.27 1.05 0.5 99.5 0.094

v 0.12 1.43 38.88 0.99 2.2 97.9 0.721 Snx 0.57 1.56 52.43 1.14 0.6 99.4 o120

v 0.24 0.99 19.77 0.70 1.2 98.9 0.284 Ssx 0.44 1.27 34.80 0.93 0.4 99.6 0.137

v 0.34 2.O4 81.67 1.43 4.3 95.7 0.462 Lsx 0.61 1.32 40.33 1.00 0.5 99.5 0.053

v 0.16 1.25 30.1 3 0.87 1.7 98.3 0.584

ULL X 0.60 1.23 35.99 0.95 o.4 99.6 0.044

v 0.07 0.70 9.48 0.49 0.6 99.5 0.666 LLH x 0.16 1.43 39.59 0.99 o.4 99.6 0.615

v -o.o2 o.77 11.26 0.53 0.6 99.4 0.891 Li x 0.47 1.28 35.75 0.95 o.4 99.6 0.119

v 0.28 0.94 18.55 0.68 0.9 99.1 0.1 94 Si x o.42 1.12 27.36 0.83 0.3 99.7 0.107

v 0.00 1.01 19.26 0.69 0.9 99.1 0.995

ST Pog x 0.28 1.28 32.83 0.91 0.3 99.7 0.335

v 0.18 2.16 89.52 1.50 4.0 96.0 o.712

STMe X 1.13 2.12 110.87 1.66 1.1 98.9 0.o27

v 0.13 o.62 7.54 0.43 o.4 99.6 o.344

(*) significant at p<0.05

(**) signihcant at p<0.01

('t * +) significant at p<0.00 I RESULTS 94

Table 14 Error Study : Results of double determinations for variables. Hard tissue variables: variable mean diff sd diff Sumdiffsq Se E(var) Reliability T prob.

SN-FH -0.25 1.16 26.66 0.82 10.7 89.3 0.348

SNA -0.14 0.76 11.23 0.53 2.4 97.6 o.431

MaxPl-SN -0.08 1.O4 20.76 0.72 6.9 93.1 o.721

Co-A 0.61 0.96 24.75 0.79 2.9 97.1 0.010

U1-SN 0.04 1.09 22.48 0.75 1.4 98.6 o.877

U1-NA 0.17 1.11 23.81 0.77 1.6 98.4 0.494

U1-NA(mm) 0.22 0.63 8.47 0.46 4.9 95.1 0.127

U1-MaxPl 042 0.95 20.68 o.72 1.6 98.4 0.706

U1-L1 o.25 1.85 66.05 1.28 2.O 98.0 0.698

LOP -0.78 0.92 28.O2 0.84 8.3 91.7 0.001

ANB -0.1'l 0.57 6.40 0.40 4.1 95.9 0.394

L1-NB 0.10 1.36 35.11 0.94 2.1 97.9 0.748

L1-NB(mm) 0.00 0.35 2.29 0.24 1.2 98.9 0.965

IMPA 0.61 1.34 41.57 1.O2 2.4 97.6 0.058

L1-MP 0.15 0.85 14.31 0.60 6.2 93.8 o.431

SNB -0.03 0.64 7.90 o.44 2.O 98.0 0.861

Co-Gn 0.65 1.03 28.70 0.85 2.2 97.8 0.011

Ar-Gn 0.39 0.95 20.10 o.71 1.5 98.5 0.079

Co-Go o.67 1.45 48.77 1.10 6.8 93.2 0.054

Ar-Go 0.49 1.12 28.61 0.85 4.5 95.5 0.066

UFH 0.27 1.18 27.71 0.83 10.0 90.0 0.319

LFH o.20 0.62 8.06 0.45 1.3 98.7 0.166

UFHLFH 0.19 2.35 105.21 1.62 8.2 91.8 o.725

N-Me 0.43 1.01 23.19 0.76 2.4 97.6 0.073

S-Go 0.57 1.13 30.99 0.88 3.3 96.8 0.036

PFHAFH o.41 0.87 17.64 0.66 3.2 96.8 0.046

FMA -0.33 1.18 28.48 0.84 2.8 97.2 0.226

A-Svert -0.01 0.71 9.58 0.49 1.2 98.8 0.928

B-Svert 0.16 0.70 9.75 0.49 0.7 99.3 0.319

PogSvert 0.16 0.87 14.92 0.61 0.8 99.2 0.427

OJ 0.11 0.39 3.16 o.28 2.2 97.8 o.240

OB 0.10 0.40 3.16 0.28 2.1 98.0 o.287 RBsur.rs 95

Table l5 Error Study : Results of double determinations for variables. Soft tissue variables:

mean diff sd Se E(var) Reliability T prob variable diff lsumdiffse F.conv -0.06 1.82 62.74 1.25 9.5 90.5 o.877

N-Lang -0.58 3.01 178.93 2.12 6.0 94.0 0.399

L-Mfold 0.86 3.61 261.78 2.56 4.2 95.8 0.301

Hangle -0.31 1.48 43.53 1.04 3.0 97.0 0.368

Ls-A 0.05 0.87 14.32 0.60 9.4 90.6 0.799

Li-B -0.02 1.27 30.67 0.88 10.9 89.1 0.954

ST TFH 0.20 1.64 52.O8 1.14 3.9 96.1 0.600

ST UFH 0.03 1.55 45.74 1.O7 9.0 91.0 0.940

ST LFH -0.13 1.08 22.41 0.75 2.7 97.3 0.600

STLFH% -0.13 0.95 17.50 0.66 7.9 92.2 0.540

Ls-E 0.11 0.42 3.62 0.30 2.2 97.8 0.271

Li-E 0.01 o.32 1.98 o.22 0.8 99.2 0.913

ULL 0.17 0.76 11.68 0.54 6.2 93.8 0.319

LLL -0.59 1.26 37.11 0.96 7.9 92.1 0.048

STP-STN 0.65 2.35 1 13.56 1.68 9.5 90.6 0.230

Sn-Svert 0.24 0.76 12.21 0.55 1.3 98.7 0.1 84

SsSvert 0.23 0,81 13.46 0.58 1.3 98.7 0.210

LsSvert o.41 0.79 15.08 0.61 1.2 98.8 0.032

LiSvert 0.30 0.81 14.32 0.60 1.1 98.9 0.111

SiSvert 0.28 0.65 9.43 0.49 o.7 99.3 0.071

STPSvert 0.16 0.87 14.96 0.61 o.7 99.3 0.409

(*) significant at p<0.05

(* *) significant at p<0.01

* ,r, (i< ) significant at p<0.001

Reliability was in excess of 89 percent for all variables. The upper molar distal cusp point was not used in the determination of any of these variables.

Seven craniofacial and soft tissue variables had statistically significant systematic errors (Co-A, LOP, Co-Gn, S-Go, PFHAFH, LLL and Ls-Svert). RBsulrs 96

4.2 PRE.TREATMENT AGES AND TREATMENT TIMES

Section 4.2 (Table 16) encompasses an analysis of the ages and the observed treatment times for each functional appliance group, It should be noted that the "tteatment time" for the purpose of this study was the actual observation time. That is, the time between the commencement and completion cephalograms. Actual treatment time may in fact have been longer if treatment continued after the second cephalogram was obtained.

Table 16 Tables of pre-treatment age (in years) and length of treatment (in days).

ACTIVATORS / HEADGEAR

males =17 TOTAL MALES FEMALES females=18 MEAN SD MEAN SD MEAN SD

Age 11.1 1.69 11.2 1.71 11.0 1.72

Tx Time 610 308 609 323 610 303

CLARK TWIN BLOCK

males=17 TOTAL MALES FEMAI-ES females=13 MEAN SD MEAN SD MEAN SD

Age 10.6 1.39 10.7 1.61 10.5 1.09

Tx Time 465 144 473 136 454 160

FRÄNKEL

males=15 TOTAL MALES FEMALES

females=14 MEAN SD MEAN SD MEAN SD

Age 10.8 1.31 10.9 1.56 1O.7 1.O2 Tx Time 596 257 604 234 588 288 Inconsistent criteria were used to define the end of treatment decision. In some cases, completion of treatment was defined by removal of the functional appliance, with no mention of a retention phase while in other situations it was defined as moving into "night only" wear.

The strength of the correlation between age and pre-treatment craniofacial and soft tissue variables, and the measure of shared variation (Johnston, 1993), can be found in Appendix 8.3. The correlations between treatment time and the treatment change in the craniofacial and soft tissue variables are also displayed in Appendix 8.3. Many values were statistically significant, especially in the male activator group. Some variables RESULTS 97

displayed high correlations with treatment time and those with correlations of determination of greater than 50Yo are highlighted. The data were not adjusted for age'

4.3 SEX COMPARISONS OF PRE.TREATMENT HARD AND SOFT TISSUE VARIABLES

Section 4.3 (table 17 to table 22) preserrts a tabulated breakdown of the pre-treatment variables for each of the three groups. F-tests were performed initially, then the appropriate unpaired t-test, for either equal or unequal variances, was applied to assess the differences between males and females. Significance of F-values are tabulated. The variables which possessed statistically significant differences, between males and females are highlighted in the last column.

The genders in the activator with headgear group were fairly similar pre-treatment with respect to their craniofacial variables. However, ramal length was greater and overbite was deeper in the males. The genders had significant pre-treatment differences in six soft tissue variables, These included the soft tissue upper and total face heights, soft tissue pogonion to soft tissue nasion and the upper lip measurements to the sella vertical reference plane (subnasale, sulcus superius, labrale superius). These indicated that the males had greater dimensions. Post-treatment, the differences which existed in the vertical dimension evaporated.

The Clark Twin Block sample exhibited few pre-treatment skeletal differences between males and females. These were in the variables SN-FH, Ar-Gn and N-Me. The only dental variable to be statistically different between the sexes was the LI-MP, which exhibited 1.7mm increased dimension in the males.

The pre-treatment differences between the genders in the soft tissue variables consisted of an increased soft tissue lower face height in the males, which produced a significant increase in their total soft tissue face height. The lower lip length was also 2.lmm longer in the males pre-treatment which was significant at the p<0.01 level.

Three skeletal (Co-Go, LFH, A-Svert), three dental (LOP, LI-MP, OJ) and four soft tissue variables (Ls-A, Sn-Svert, Ss-Svert, Ls-Svert) were significantly different between the genders pre-treatment in the Fränkel appliance group. Larger dimensions were displayed in males for all variables. RESULTS 98

Table 17 Activator : Sex comparisons of pre-treatment hard tissue variables:

Pre-Tx. TOTAL n=35 MALE n=17 FEMALE n=í8 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

SN-FH 9.4 2.72 9.7 2.76 9.1 2.73 0.96 0.527

SNA 81.7 3.53 81.5 3.35 82.0 ó. /þ 0.65 0.662

MaxPl-SN 6.3 2.75 5.7 2.23 6.9 3.11 0.19 0.1 89

Co-A 83.7 4.29 85.0 2.46 82.4 5.26 0.00 0.071

U1-SN 107.1 6.42 106.7 6.12 107.6 6.85 0.66 0.699

U1-NA 25.4 6.20 25.2 5.69 25.6 6.82 0.47 0.879

U1-NA(mm) 5.2 1.94 5.4 2.09 5.0 1.83 0.60 0.546

U'l-MaxPl 1 13.5 6.22 112.4 5.53 114.5 6.81 0.41 0.327

U,I-11 125.1 9.10 125.3 8.42 125.0 9.94 0.51 0.931

LOP 21.2 2.37 21.4 2.41 21.0 2.39 0.96 0.579

ANB 5.8 1.79 5.6 1.61 6.0 1.98 o.42 0.553

L1-NB 23.6 6.07 23.9 5.71 23.4 6.55 0.59 0.841

L1-NB(mm) 4.5 2.15 4.5 2.O7 4.4 2.28 0.71 0.844

IMPA 92.3 6.10 93.4 5.97 91.3 6.22 0.87 0.319

L1-MP 16.2 2.32 16.3 2.29 16.0 2.40 0.85 0.734

SNB 75.9 3.O2 75.8 3.30 76.0 2.83 0.53 0.877

Co-Gn 102.3 5.34 104.O 4.69 100.7 5.55 0.51 0.068

Ar-Gn 94.8 5.O7 96.0 3.90 93.6 5.84 0.11 0.1 54

Co-Go 48.6 4.13 50.0 4.25 47.2 3.62 o.52 0.042 "

Ar-Go 39.0 3.78 39.9 3.48 38.2 3.95 0.62 0.172

UFH 47.4 2.74 47.8 2.28 47.1 3.13 0.21 0.414

LFH 61.2 3.71 61.9 4.17 60.5 3.18 o.28 o.265

UFHLFH 77.8 6.12 77.5 5.41 78.0 6.87 0.35 o.812

N-Me 105.8 4.57 107.0 5.22 104.7 3.64 0.15 0.125

S-Go 66.9 4.49 68.3 4.52 65.6 4.16 o.73 0.071

PFHAFH 63.2 3.86 63.9 4.19 62.6 3.52 0.48 0.352

FMA 26.0 4.76 25.0 4.90 27.1 4.53 0.75 0.1 97

A-Svert 64.4 4.73 65.9 4.23 62.9 4.83 0.60 0.059

B-Svert 54.5 6.15 56.0 6.18 53.1 5.93 0.87 0.1 56

PogSvert 54.6 6.82 56.3 6.78 52.9 6.60 0.91 0.137

OJ 7.7 2.01 7.6 2.18 7.8 1.89 0.56 0.778 * OB 4.7 1.93 5.4 1.68 4.O 1.95 o.57 0.034 Rssulrs 99

Table 18 Activator: Sex comparisons of pre-treatment soft tissue variables:

Pre-Tx. TOTAL n=35 MALE n=17 FEMALE n=18 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

F.conv 128.O 3.89 128.O 3.96 128.1 3.94 0.98 0.961

N-Lang 124.1 '10.15 124.0 10.44 124.3 10.17 0.91 0.939

L-Mfold 122.7 15.65 1 18.3 13.29 126.9 16.87 0.35 0.1 01

Hangle 146.3 5.89 145.6 5.41 147.1 6.38 0.51 0.460

Ls-A 20.5 1.92 21.1 1.83 19.9 1.87 0.94 0.060

Li-B 21.5 2.86 21.8 3.26 21.2 2.47 0.27 0.513 * ST TFH 1 10.3 5.28 112.2 6.09 108.5 3.71 0.05 0.036

ST UFH 47.0 4.09 48.5 4.26 45.6 3.45 0.40 0.030 "

ST LFH 68.4 3.91 69.0 4.60 67.9 3.17 0.14 0.410

STLFH% 62.1 2.54 61.5 2.51 62.6 2.52 0.98 0.209

Ls-E 1.1 1.82 1.3 1.59 1.1 2.05 o.32 o.747

Li-E 1.0 2.31 1.4 2.15 0.5 2.44 0.63 0.260

ULL 20.3 2.34 20.6 2.20 20.o 2.48 0.64 0.453

LLL 44.6 3.66 44.6 3.95 44.6 3.47 0.61 0.967 * STP-STN 93.2 5.54 95.3 6.24 91.2 4.03 0.08 0.028 ** Sn-Svert 78.4 5.06 80.7 4.56 76.2 4.62 0.96 0.007 * SsSvert 78.0 5.38 80.0 4.95 76.0 5.15 0.88 0.026 * LsSved 80.6 5.64 82.9 4.91 78.5 5.55 0.63 0.018

LiSvert 74.1 6.56 76.3 6.16 72.1 6.44 0.86 0.059

SiSveft 64.7 6.27 66.1 6.48 63.3 5.93 0.72 0.195

STPSvert 65.4 7.71 67.0 7.90 64.0 7.46 0.81 0.260

(*) significant at p<0.05

(* *) significant at p<0.01

(i. * *) significant at p<0.001 RESULTS 100

Table 19 Glark Twin Block: Sex comparisons of pre-treatment hard tissue variables:

Pre-Tx. TOTAL n=30 MALE n=17 FEMALE n=í3 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

SN-FH 10.2 2.45 11.0 2.54 9.2 1.96 0.37 0.042*

SNA 81.2 3.37 80.9 3.53 81.5 3.27 0.80 0.598

MaxPl-SN 7.0 2.65 6.8 2.71 7.3 2.65 0.96 0.585

Co-A 83.9 4.55 85.0 4.66 82.5 4.15 0.70 0.136

U1-SN 107.8 6.84 108.5 7.27 106.9 6.40 0.66 0.539

UI-NA 26.7 7.02 27.7 6.51 25.4 7.71 o.52 0.392

U1-NA(mm) 5.1 2.49 5.6 2.52 4.4 2.38 0.86 0.207

U1-MaxPl 114.9 6.22 1 15.3 6.28 114.3 6.34 0.95 0.658

U1-11 125.1 8.80 124.5 9.59 126.0 7.96 0.52 0.656

LOP 21.7 3.23 21.8 2.92 21.6 3.71 0.36 0.869

ANB 5.8 2.20 5.6 2.27 6.1 2.17 0.90 0.549

L1-NB 22.4 6.45 22.2 6.17 22.5 7.06 0.60 0.910

L1-NB(mm) 3.5 2.10 3.7 2.03 3.3 2.25 0.69 0.594

IMPA 91.7 6.37 91.6 6.51 91.8 6.44 0.99 0.948 * L1-MP 15.1 2.49 15.8 2.92 14.1 1.39 0.01 0.046

SNB 75.4 3.29 75.3 3.66 75.4 2.89 o.42 0.890

Co-Gn 101.7 6.09 103.4 6.98 99.5 3.91 0.05 0.082 * Ar-Gn 94.8 5.64 96.5 6.27 92.5 3.77 0.08 0.049

Co-Go 47.7 4.11 48.5 4.62 46.6 3.18 0.19 0.206

Ar-Go 38.7 3.50 39.6 3.56 37.5 3.19 0.71 0.109

UFH 47.5 2.46 48.0 2.87 46.8 1.65 0.06 0.190

LFH 59.8 4.O7 61.0 4.09 58.3 3.64 0.70 0.073

UFHLFH 79.7 5.43 79.0 5.07 80.6 5.94 0.55 0.415 * N-Me 104.6 5.31 106.3 5.81 102.3 3.64 0.11 0.039

S-Go 65.8 4.25 66.9 4.76 64.4 3.10 o.14 0.112

PFHAFH 62.9 3.24 62.9 2.89 63.0 3.77 0.32 0.944

FMA 25.1 5.30 24.4 4.11 26.1 6.59 0.08 0.377

A-Sved 64.7 3.60 65.1 3.70 64.3 3.55 0.90 0.555

B-Svert 54,9 5.31 55.2 5.73 54.4 4.89 0.59 0.685

PogSvert 55.1 6.39 55.6 6.95 54.6 5.78 o.52 0.684

OJ 8.4 2.53 8.5 2.55 8.2 2.59 0.93 0.793

OB 5.1 2.11 5.3 2.32 4.8 1.86 0.44 0.562 Rnsutrs

Table 20 Glark Twin Block : Sex comparisons of pre-treatment soft tissue variables:

Pre-Tx. TOTAL n=30 MALE n=17 FEMALE n=13 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

F.conv 127.1 4.20 127.4 4.55 126.7 3.82 0.55 0.644

N-Lang 125.7 8.46 125.4 7.81 126.2 9.56 0.44 0.810

L-Mfold 120.0 11.30 117.9 9.51 122.8 13.17 o.22 0.247

Hangle 147.7 6.41 147.2 5.89 148.4 7.22 o.44 o.617

Ls-A 19.7 2.22 20.1 2.30 19.2 2.10 0.76 o.292

Li-B 20.2 2.49 20.8 2.13 19.4 2.79 0.31 0.133 * ST TFH 109.3 6.19 111.3 6.52 106.8 4.86 0.31 0.048

ST UFH 46.7 3.29 46.9 3.39 46.4 3.26 0.91 0.722 * ST LFH 67.9 5.14 69.9 5.13 65.4 4.03 0.40 0.014

STLFH% 62.1 2.37 62.8 2.04 61.2 2.57 0.38 0.075

Ls-E 0.5 2.28 0.8 2.O4 0.1 2.60 0.36 0.453

Li-E -0.3 2.66 0.0 2.28 -0.6 3.16 0.22 0.570

ULL 20.1 2.O5 20.6 2.12 19.5 1.86 0.65 0.162 ** LLL 43.9 2.98 45.1 2.42 42.3 2.99 o.42 0.009

STP-STN 92.9 5.75 94.1 5.86 91.4 5.43 0.80 o.202

Sn-Svert 78.7 4.04 79.6 4.19 77.6 3.69 0.67 0.1 96

SsSvert 77.9 4.18 78.6 4.59 76.9 3.54 0.37 0.286

LsSvert 80.7 4.99 81.8 5.23 79.3 4.43 0.57 o.171

LiSvert 73.7 4.78 74.6 5.36 72.6 3.82 0.24 o.262

SiSvert 64.7 5.16 65.0 6.02 64.2 3.95 0.14 0.658

STPSvert 66.3 6.94 67.2 7.32 65.2 6.52 0.69 0.455

(*) signihcant at p<0.05

(* *) signihcant at p<0.01

(***) significant at p<0.001 RESULTS t02

Table 2l Fränkel : Sex comparisons of pre-treatment hard tissue variables:

Pre-Tx. TOTAL n=29 MALE n=r sl FEMALE n=14 MvsF MvsF

VARIABLE MEAN SD MEAN .ol MEAN SD F-prob. T-prob. Signif

SN-FH 10.0 2.15 10.5 2.07 9.6 2.23 0.79 0.290

SNA 81.4 3.14 81.8 3.s7 80.9 2.64 0.29 0.416

MaxPl-SN 7.4 2.66 6.6 2.71 8.3 2.39 0.66 0.084

Co-A 83.8 4.14 85.1 4.38 82.5 3.51 0.43 0.083

U1-SN 105.1 7.59 107.6 8.74 102.4 5.15 0.06 0.061

U1-NA 23.7 6.91 25.8 8.05 21.5 4.77 0.07 0.096

U1-NA(mm) 4.3 2.24 4.6 2.43 3.9 2.O4 0.53 0.395

U'l-MaxPl 112.5 6.68 114.2 8.06 1 '10.6 4.39 0.04 o.152

U1-11 124.4 9.90 123.1 12.96 125.9 5.12 0.00 0.461 * LOP '19.5 2.76 20.5 3.07 18.4 2.01 0.14 0.047

ANB 6.3 2.15 6.6 2.47 6.0 1.78 0.25 o.425

L1-NB 25.5 6.25 24.5 8.14 26.7 3.16 0.00 0.342

L1-NB(mm) 4.4 1.92 4.1 2.25 4.7 1.52 0.17 0.479

IMPA 95.1 6.47 94.4 8.45 95.9 3.47 0.00 0.512 * L1-MP 14.7 2.46 15.7 2.59 13.7 1.91 0.28 0.029

SNB 75.1 2.66 75.2 2.64 74.9 2.76 0.87 0.754

Co-Gn 100.2 4.60 101 .8 3.77 98.5 4.91 0.34 0.051

Ar-Gn 93,0 4.89 93.9 4.05 92.1 5.66 0.23 0.335 * Co-Go 47.O 3.45 48.5 2.92 45.3 3.32 0.64 0.012

Ar-Go 37.7 2.99 38.6 2.55 36.9 3.26 0.37 o.125

UFH 47.4 2.51 47.6 2.68 47.2 2.40 0.69 0.733 * LFH 58.7 3.62 60.0 3.52 57.2 3.27 0.79 0.040

UFHLFH 81.1 6.89 79.6 7.67 82.7 5.79 o.32 o.237

N-Me 103.3 3.78 104.5 3.25 102.0 3.99 0.45 0.074

S-Go 64.5 4.O7 65.9 3.28 63.0 4.40 0.29 0.052

PFHAFH 62.5 3.51 63.1 3.26 61.8 3.74 0.62 0.310

FMA 25.3 4.21 24.4 4.07 26.2 4.32 0.82 0.257 . A-Svert 64.2 4.30 65.8 4.14 62.5 3.91 0.84 0.036

B-Svert 53.5 5.34 54.8 5.07 52.0 5.42 0.80 0.1 63

PogSveft 53.5 6.10 55.0 6.O2 51.8 5.94 0.97 0.1 58 *" OJ 7.2 2.O1 8.2 2.25 6.2 0.97 0.01 0.004

OB 5.6 2.41 6.2 2.44 4.9 2.29 0.83 0.1 78 RBsulrs 103

Table 22 Fränkel : Sex comparisons of pre'treatment soft tissue variables

Pre-Tx. TOTAL n=29 MALE n=l 5l FEMALE n=14 MvsF MvsF

VARIABLE MEAN SD MEAN *l MEAN SD F-prob. T-prob. Signif

F.conv 127.0 3.49 126.7 3.60 127.3 3.48 0.91 0.607

N-Lang 128.1 8.30 128.4 6.96 127.9 9.79 0.22 0.859

L-Mfold 124.4 10.83 122.4 12.69 126.5 8.37 o.14 0.321

Hangle 146.1 5.72 145.2 5.93 147.0 5.52 0.80 0.386 * Ls-A 19.3 1.69 19.9 1.73 18.7 1.45 o.52 0.047

Li-B 21.8 2.23 21.5 2.58 22.2 1.81 o.21 0.426

ST TFH 107.1 5.28 108.7 3.54 105.4 6.35 0.04 0.'100

ST UFH 46.3 3.23 47.0 1.83 45.6 4.22 0.00 0.263

ST LFH 66.1 4.O1 67.2 3.66 64.9 4.16 0.64 0.131

STLFH% 61.7 2.10 61.8 1.95 61.6 2.32 o.52 0.857

Ls-E 1.0 1.77 1.4 1.86 0.6 1.63 0.65 o.254

Li-E 0.9 '1.96 0.7 2.02 1.1 1.94 0.89 0.614

ULL 20.1 1.75 20.4 1.57 19.9 1.94 0.44 0.406

LLL 43.4 3.42 43.6 2.69 43.2 4.16 o.12 0.714

STP-STN 90.4 4.93 92.0 4.04 88.7 5.37 0.30 0.076 * Sn-Svert 78.1 4.31 80.0 3.82 76.2 4.04 0.84 0.016 * SsSved 76.9 4.46 78.7 3.94 75.0 4.26 0.77 0.019 * LsSvert 79.7 5.13 81.8 3.83 77.4 5.53 0.19 0.021

LiSvert 73.5 4.84 74.8 3.97 72.1 5.43 0.26 0.1 39

SiSvert 63.9 5.15 65.2 4.75 62.4 5.35 0.66 0.1 51

STPSvert 64.5 6.22 66.0 6.43 63.0 5.83 0.73 0.209

(*) significant at p<0,05

(* *) significant at p<0.01

(* r< i<) significant at p<0.001 RESULTS 104

4.4 SEX COMPARISONS OF POST.TREATMENT HARD AND SOFT TISSUE VARIABLES

Section 4.4 (Table 23 to Table 28) illustrates the post-treatment comparisons for each appliance and the statistical significance of differences between males and females at this stage.

Post-treatment, the activator with headgear group displayed only two craniofacial and five soft tissue variables which were significantly different between the sexes. UFH and A-Svert displayed greater dimensions in males. The L-Mfold was significantly more obtuse in the females post-treatment, even though no signif,rcance between the genders was determined pre-treatment. The other significant soft tissue variables were ULL, Sn- Svert, Ss-Svert and Ls-Svert, which all displayed greater dimensions in males.

The Clark Twin Block sample had significant differences between genders in eight craniofacial variables post-treatment. Co-A and Co-Gn were significant at the p<0.01 level while Ar-Gn, Co-Go, UFH, LFH, N-Me and LI-MP were significant at the p<0.05 level. Eight soft tissue variables were also significant post-treatment. These included Ls-[, Sn-Sveft, Ss-Svert, Ls-Svert and Li-Svert at the p<0.05 level, STTFH and STLFH at the p<0.01 level and LLL atthe p<0.001 level.

Fost-treatment, the sexes in the Fränkel appliance group exhibited 13 statistically signifrcant differences in the variables. These included seven hard tissue and six soft tissue variables. MaxPl-SN, Ls-A and ULL displayed significance at the p<0.01 level while Co-Go, Ar-Go, LFH, UFHLFH, S-Go, A-Svert, Sn-Svert, Ss-Svert, LsSvert and Li-Svert were all significant at the p<0.05 level. RESULTS 105

Table 23 Activator: Sex comparisons of post-treatment hard tissue variables

Post-Tx. TOTAL n=35 MALE n=17 FEMALE n=18 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

SN-FH 9.5 2.98 10.0 3.26 9.0 2.68 0.43 0.298

SNA 81.5 3.76 81.4 3.61 81.6 3.99 0.70 0.894

MaxPl-SN 7.1 3.01 7.0 2.71 7.2 3.35 0.40 0.843

Co-A 85.3 4.91 86.9 3.43 83.8 5.69 0.05 0.063

U1-SN 99.6 6.07 100.3 5.64 98.9 6.54 0.56 0.502

U1-NA 18.1 6.33 18.9 6.38 17.3 6.36 0.99 0.469

U1-NA(mm) 2.7 2.18 3.0 2.O2 2.4 2.35 0.55 o.432

U'l-MaxPl 106.7 6.06 107.3 5.66 1 06.1 6.51 0.58 0.566

U1-11 134.0 9.56 133.0 9.62 134.9 9.68 0.98 0.550

LOP 20.7 2.67 20.1 2.86 21.2 2.44 0.53 0.223

ANB 4.3 1.78 4.5 1.70 4.2 1.89 o.67 0.543

L1-NB 23.6 5.97 23.6 5.91 23.6 6.20 0.85 0.991

L1-NB(mm) 4.7 2.19 4.7 2.31 4.6 2.13 0.75 0.896

IMPA 90.8 5.89 91.9 5.89 89.8 5.89 1.00 0.314

L1-MP 17.6 2.35 18.2 2.31 17.O 2.29 0.97 0.112

SNB 77.2 3.48 76.9 3.51 77.4 3.53 0.98 0.652

Co-Gn 107.6 6.23 108.8 5.65 106.3 6.67 0.51 0.241

Ar-Gn 1 00.1 6.70 101.4 5.5'l 98.8 7.58 0.21 o.242

Co-Go 51.5 4.83 52.4 4.98 50.7 4.68 0.80 0.305

Ar-Go 42.O 5.33 42.9 4.98 41.2 5.64 o.62 0.346

UFH 49.1 2.96 50.1 2.67 48.1 2.96 0.68 0.044 "

LFH 64.1 4.08 64.6 4.80 63.6 3.34 0.15 0.480

UFHLFH 76.7 5.28 77.7 4.80 75.7 5.66 o.52 o.270

N-Me 1 10.8 5.43 112.4 6.19 109.3 4.25 0.13 0.099

S-Go 70.7 6.28 72.3 6.65 69.1 5.66 0.51 0.'133

PFHAFH 63.8 4.41 64.4 5.04 63.2 3.76 o.24 0.419

FMA 26.1 5.43 24.8 5.53 27.3 5.18 0.79 o.171

A-Sved 64.7 5.03 66.6 4.60 62.8 4.82 0.86 0.022"

B-Svert 56.2 6.68 57.7 6.47 54.8 6.75 0.87 o.207

PogSvert 56.1 7.72 57.9 7.34 54.4 7.90 o.77 0.191

OJ 3.4 187 4.O 2.14 2.9 1.44 o.12 0.081

OB 2.8 1.71 3.0 1.76 2.5 1.66 0.8'l o.327 RBsulrs 106

Table 24 Activator: Sex comparisons of post-treatment soft tissue variables:

Post-Tx. TOTAL n=35 MAI-E n=17 FEMALE n=18 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

F.conv 128.7 4.60 128.5 4.59 129.0 4.72 0.91 0.735

N-Lang 128.2 8.40 128.8 7.36 127.6 9.45 0.33 0.668 * L-Mfold 135.6 12.37 131.2 9.94 139.7 13.25 0.26 0.040

Hangle 153.1 6.14 152.3 5.O2 153.8 7.11 0.17 o.492

Ls-A 20.7 1.74 21.2 1.80 20.2 1.57 0.58 0.091

Li-B 22.3 2.49 22.5 2.55 22.1 2.48 0.91 0.680

ST TFH 115.2 5.96 117.1 6.35 1 13.3 5.07 0.37 0.060

ST UFH 49.1 3.94 50.2 4.16 48.1 3.52 0.50 0.102

ST LFH 71.0 4.75 72.0 5.01 70.1 4.43 0.62 o.231

STLFH% 61.6 2.53 61.5 2.58 61.8 2.55 0.96 0.708

Ls-E -1.4 2.09 -1.3 2.07 -1.6 2.15 0.89 0.726

Li-E -o.4 2.95 -0.3 3.02 -0.5 2.96 0.94 0.849 * ULL 21.1 2.20 21.9 2.19 20.4 1.99 0.69 0.038

LLL 48.2 3.86 48.2 4.53 48.2 3.23 0.18 0.975

STP-STN 98.0 5.33 99.8 6.19 96.3 3.80 0.05 0.052 *" Sn-Svert 79.6 5.88 82.2 5.43 77.1 5.30 o.92 0.009 * SsSvert 78.1 5.98 80.5 5.51 75.8 5.61 0.95 0.018

LsSvert 80.2 6.21 82.6 5.85 78.0 5.80 0.97 0.024 "

LiSvert 75.7 6.46 77.7 5.90 73.9 6.58 0.67 0.082

SiSvert 67.7 7.O1 68.9 6.95 66.6 7.08 0.95 0.345

STPSvert b /.þ 9.01 69.3 8.76 66.0 9.'19 0.85 0.282

(*) significant at p<0,05

(* *) significant at p<0.01

(* *. *) significant at p<0.001 RESULTS 107

Table 25 Glark Twin Block: Sex comparisons of post-treatment hard tissue variables:

Post-Tx. TOTAL n=30 MALE n=17 FEMALE n=13 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

SN-FH 10.0 2.66 10.8 2.66 8.9 2.35 0.68 0.053

SNA 80.7 3.30 80.7 3.28 80.7 3.46 0.82 0.994

MaxPl-SN 7.5 2.45 7.3 2.68 7.7 2.18 0.48 0.658 ** Co-A 85.0 4.65 87.0 4.09 82.4 4.16 0.93 0.006

U1-SN 101 .0 5.49 102.2 6.24 99.6 4.08 0.14 o.201

U1-NA 20.4 5.19 21.5 4.82 '18.9 5.46 0.63 o.174

U1-NA(mm) 3.4 2.09 3.7 2.06 2.9 2.11 0.91 o.277

U1-MaxPl 108.5 4.49 109.5 4.85 107.2 3.78 0.39 0.186

U1-L1 128.6 8.61 127.8 8.87 129.6 8.50 0.90 0.580

LOP 19.5 3.84 19.9 3.26 18.9 4.56 o.21 o.487

ANB 3.9 2.16 3.8 1.98 4.1 2.46 0.41 o.767

L1-NB 27.1 7.54 26.8 8.08 27.4 7.09 0.66 0.839

Ll-NB(mm) 5.1 2.70 5.2 2.69 5.0 2.81 0.85 0.853

IMPA 94.8 8.25 94.4 8.87 95.4 7.68 0.62 0.742 * L1-MP 15.2 2.35 15.9 2.57 14.2 1.64 0.12 0.040

SNB 76.7 3.38 76.8 3.89 76.6 2.72 0.21 0.853 *" Co-Gn '106.3 6.3'l 108.9 6.77 102.8 3.56 0.03 0.004 * Ar-Gn 99.5 5.97 101 .5 6.36 96.8 4.35 0.19 0.031 * Co-Go 50.3 4.76 51.9 4.69 48.3 4.16 0.68 0.037

Ar-Go 41.6 4.43 42.5 3.82 40.4 5.O2 0.31 o.204 * UFH 49.0 2.61 49.8 2.97 47.9 1.58 0.03 0.033

LFH 62.2 4.10 63.5 4.43 60.5 2.96 0.16 0.042 "

UFHLFH 78.9 5.12 78.6 5.04 79.4 5.39 0.79 0.686 * N-Me 108.9 5.52 't 10.9 6.29 106.3 2.77 0.01 0.012

S-Go 69.0 5.19 70.3 5.66 67.3 4.13 0.27 oj26

PFHAFH 63.4 3.69 63.3 3.05 63.4 4.53 o.14 0.939

FMA 25.5 5.73 24.7 4.34 26.4 7.25 0.06 0.438

A-Svert 65.1 3.76 66.0 3.42 64.0 3.99 0.56 o.142

B-Svert 57.2 5.77 58.2 5.93 56.0 5.53 0.82 0.303

PogSvert 57.4 6.65 58.5 7.09 56.0 6.01 0.57 0.317

OJ 3.2 1.75 3.4 1.64 2.9 '1.91 0.55 0.430

OB 2.9 1.80 3.3 1.78 2.4 1.76 0.99 0.1 89 RESULTS 108

Table 26 Glark Twin Block : Sex comparisons of post-treatment soft tissue variables:

Post-Tx. TOTAL n=30 MALE n=17 FEMALE n=13 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

F.conv 129.0 4.31 129.2 4.43 128.6 4.29 0.93 0.704

N-Lang 129.8 9.05 129.1 8.55 130.6 9.95 0.56 0.650

L-Mfold 134.2 13.15 130.6 12.16 138.7 13.44 0.70 0.095

Hangle 154.4 6.34 153.2 5.66 156.0 7.05 0.41 o.234

Ls-A 19.7 2.32 20.5 2.50 18.6 1.57 0.'11 0.022*

Li-B 22.2 3.27 23.1 3.26 21.0 2.97 o.75 0.075 ** ST TFH 1 13.6 5.68 1 15.9 6.23 110.7 3.04 0.02 0.006

ST UFH 49.0 2.98 49.5 3.34 48.4 2.44 o.27 0.351 ** ST LFH 69.5 4.70 71.5 4.51 66.8 3.52 0.39 0.004

STLFH% 61.1 2.24 61.7 1.81 60.3 2.57 0.19 0.099

Ls-E -1.9 2.34 -1.3 2.O4 -2.6 2.58 0.37 0.133

Li-E -0.5 3.09 0.0 2.87 -1.1 3.38 0.53 0.362

ULL 20.8 2.20 21.1 2.25 20.3 2.14 0.87 0.348 *** LLL 47.0 2.99 48.5 2.30 45.1 2.70 0.54 0.001

STP-STN 96.6 5.20 98.1 6.02 94.6 3.09 0.02 0.051 * Sn-Svert 79.8 4.15 81.2 4.20 78.0 3,40 o.47 0.030

SsSvert 78.4 4.63 80.0 4.67 76.2 3.74 0.44 0.024 " * LsSvert 80.6 5.39 82.5 5.41 78.1 4.40 0.47 0.025 * LiSvert 76.8 5.36 78.7 5.11 74.3 4.81 0.85 0.025

SiSvert 68.8 5.08 70.1 5.36 67.1 4.34 0.46 0.118

STPSvert 69.4 6.97 71.O 7.23 67.3 6.24 0.62 0.148

(*) significant at p<0.05

(**) significant at p<0.01

(***) significant at p<0.001 RESULTS 109

Table 27 Fränkel : Sex comparisons of post-treatment hard tissue variables:

Post-Tx. TOTAL n=29 MALE n=15 FEMALE n=14 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

SN-FH 10.5 1.88 10.9 1.87 10.0 1.86 1.00 o.219

SNA 80.9 3.27 81.5 3.76 80.3 2.65 o.21 0.343 ** MaxPl-SN 8.1 2.92 6.8 2.27 9.6 2.93 0.36 0.008

Co-A 85.6 4.96 86.8 4.90 84.3 4.88 0.99 0.'188

U1-SN 97.6 5.45 99.2 5.78 95.9 4.65 0.44 0.097

U,I-NA 16.7 4.68 17.7 5.60 15.5 3.26 0.06 0.213

U1-NA(mm) 1.9 1.47 2.1 1.74 1.6 1.10 0.10 0.349

U1-MaxPl 105.7 4.40 106.0 5.34 105.4 3.29 0.09 o.729

U1-11 129.2 7.98 128.2 9.76 130.3 5.66 0.06 0.479

LOP 17.3 2.64 17.2 3.16 17.5 2.06 0.13 0.776

ANB 5.2 1.77 5.3 2.19 5.0 1.24 0.05 0.729

L1-NB 29.0 6.63 28.8 8.27 29.1 4.57 0.04 0.911

L1-NB(mm) 5.7 2.35 5.9 2.90 5.5 1.65 0.05 0.728

IMPA 97.2 6.33 97.3 7.97 97.1 4.21 0.03 0.945

L1-MP 15.8 2.43 16.1 2.97 15.5 1.74 0.06 0.564

SNB 75.8 2.87 76.2 2.88 75.3 2.88 1.00 0.386

Co-Gn 105.1 6.01 106.9 4.96 103.2 6.59 0.30 0.094

Ar-Gn 97.8 5.96 99.2 4.97 96.2 6.70 o.28 o.173 . Co-Go 50.2 4.O2 51.7 2.91 48.5 4.44 0.13 0.025 . Ar-Go 40.7 3.67 42.0 2.91 39.3 3.96 o.27 0.041

UFH 49.6 2.40 49.6 2.49 49.6 2.39 0.89 0.999 * LFH 61.9 3.85 63.6 3.71 60.1 3.24 0.63 0.014 * UFHLFH 80.3 5.13 78.2 5.22 82.6 4.07 0.38 0.019

N-Me 108.9 4.70 110.4 4.37 107.4 4.71 0.78 0.092 * S-Go 68.6 4.83 70.4 3.78 66.7 5.20 0.25 0.035

PFHAFH 63.0 3.52 63.8 2.88 62.1 4.O1 0.23 0.1 91

FMA 25.5 4.68 24.5 3.76 26.7 5.40 0.19 0.200 * A-Sved 64.9 4.88 66.7 4.40 63.0 4.78 0.76 0.039

B-Svert 55.2 5.98 57.1 5.19 53.1 6.27 0.49 0.o74

PogSvert 55.0 6.77 57.2 6.14 52.6 6.79 0.71 0.066

OJ 2.7 1.12 3.1 1.27 2.3 0.81 0.1 1 0.066

OB 2.9 1.89 3.0 1.91 2.7 1.93 0.96 0.633 RESULTS 110

Table 28 Fränkel : Sex comparisons of post-treatment soft tissue variables:

Post-Tx. TOTAL n=29 MALE n=15 FEMALE n=14 MvsF MvsF

VARIABLE MEAN SD MEAN SD MEAN SD F-prob. T-prob. Signif

F.conv 128.1 3.78 128.5 4.10 127.6 3,51 0.58 0.547

N-Lang 132.0 7.24 133.2 7.98 130.8 6.40 0.43 0.381

L-Mfold 140.2 10.85 138.8 11.79 141.7 9.96 0.55 0.477

Hangle 152.6 5.67 152.1 5,65 153.2 5.83 0.90 0.595 ** Ls-A 19.0 1.85 19.9 1.31 18.1 1.97 0.14 0.009

Li-B 23.3 2.56 23.5 3.36 23.O 1.32 0.00 0.595

ST TFH 113.0 6.54 115.2 5.62 110.7 6.85 0.47 0.064

ST UFH 49.3 3.72 50.0 2.85 48.5 4.44 0.11 0.263

ST LFH 69.0 4.75 70.5 4.06 67.3 5.00 0.45 0.067

STLFH% 61.0 2.31 61.2 1.76 60.8 2.84 0.09 o.642

Ls-E -1.4 1.94 -1.0 1.79 -1.8 2.09 0.57 0.285

Li-E -o.4 2.24 -0.4 1.98 -0.5 2.57 0.35 0.930 ** ULL 20.9 2.41 22.O 1.57 19.7 2.63 0.07 0.008

LLL 47.1 3.51 47.7 3.22 46.5 3.83 0.53 0.396

STP-STN 95.5 6.17 97.2 5.85 93.5 6.13 0.86 0.1 07 * Sn-Svert 79.3 5.79 81.6 4.36 76.8 6.25 o.20 0.023 * SsSvert 77.5 5.67 79.8 4.38 75.1 6.03 0.25 0.023 . LsSvert 79.6 6.23 82.0 4.56 77.1 6.89 o.14 0.030

LiSvert 75.3 5.9'l 77.4 4.58 73.0 6.46 o.21 0.041 "

SiSvert 67.3 5.89 69.3 4.62 65.2 6.53 0.21 0.065

STPSvert 67.2 6.98 69.5 5.75 64.8 7.54 0.32 0.068

(*) significant at p<0.05

(* *) significant at p<0.01

({< t<,r.) significant at p<0.001 RESULTS 111

4.5 HARD AND SOFT TISSUE TREATMENT CHANGES FOR THE ACTIVATOR, THE CLARK TWIN BLOCK AND THE FRÄNKEL

Section 4.5 (Table 29 to Table 34) illustrates the comparisons of changes during treatment with each appliance. The mean changes and their standard deviations are presented for males and females separately. Calculation of the mean changes were based on paired pre-and post-treatment measurements for each patient. Variables with signihcant differences between pre- and post-treatment, for each gender are highlighted'

A negative value indicates a decrease in the value of the variable between pre- and post- treatment.

Marked statistical significance was detected for changes in numerous craniofacial and soft tissue variables in all three functional appliance groups over the treatment period.

The SNA angle did not change significantly in any of the groups except in the females of the Clark Twin Block sample, where it actually decreased 0.9mm. The SNB angle was detected to increase significantly in all groups except the females in the Fr?inkel sample. The SN-FH, the FMA, the UFHLFH ratio and the PFHAFH ratio did not change significantly in any of the functional appliance groups.

As expected, overbite and overjet decreased a statistically signifrcant amount in all functional appliance groups. This may be associated with bias in the cases available for investigation. In general, cases which are not successfully treated with a particular functional appliance are often treated by other means.

With growth of the nose SsSvert increased significantly only in the male Clark Twin Block group (p<0.01) while overjet reduction decreased LsSvert signihcantly only in the female Clark Twin Block group.

Upper lip thickness did not change significantly in any of the appliance groups over the treatment period. RESULTS 1t2

Table 29 Activator: Means and standard deviations for treatment changes. Hard tissues:

Tx. changes MALES FEMALES

VARIABLE MEAN SD T Prob MEAN SD T Prob.

SN-FH 0.3 1.25 0.2806 -0.1 1.63 0.7313

SNA 0.0 1.14 0.8801 -o.4 1.37 0.2308 ** MaxPl-SN 1.3 1.41 0.0018 0.2 2.22 0.6394 . Co-A 1.9 2.69 0.0106 " 1.4 2.35 0.0200 *** U1-SN -6.4 5.17 0.0001 -8.7 5.45 0.0000 "** *** *** U1-NA -6.3 5.12 0.0001 -8.2 5.04 0.0000 *** U1-NA(mm) -2.5 1.74 0.0000 -2.7 1.41 0.0000 "** *** U1-MaxPl -5.1 5.22 0.0010 "*" -8.4 5.53 0.0000 *** *** U1-L,I 7.7 6.12 0.0001 9.9 6.88 0.0000 ** LOP -1.3 1.66 0.0042 0.2 2.00 0.6427 *"* *** ANB -1.1 1,03 0.0005 -1.8 '1.15 0.0000

L1-NB -0.3 3.40 0.7622 0.1 4.05 0.8832

L1-NB(mm) 0.2 0.76 0.2919 o.2 1.13 0.3637

IMPA -1.5 2.97 0.0556 -1.4 3.74 0.1 209 *" L1-MP 1.9 2.21 0.0027 0.9 1.43 0.0152 " *** *t* SNB 1.0 0.88 0.0002 1.4 1.36 0.0004 *"* Co-Gn 4.8 3.98 0.0001 5.6 3.56 0.0000 "** *** *** Ar-Gn 5.4 3.49 0.0000 5.2 2.88 0.0000

Co-Go 2.4 3.5'l o.0121* 3.5 3.20 0.0002 "** *"* **" Ar-Go 3.0 2.91 0.0007 3.0 2.53 0.0001 *** UFH 2.3 1.28 0.0000 1.0 2.10 0.0540 *** *** LFH 2.7 2.79 0.0010 3.1 2.26 0.0000

UFHLFH o.2 3.30 0.7994 -2.3 5.O2 0.0696 *** N-Me 5.3 3.34 0.0000 "** 4.7 2.68 0.0000 *** *** S-Go 4.1 3.71 0.0004 3.6 2.54 0.0000

PFHAFH 0.5 1.54 0.1 730 0.5 1.24 o.0812

FMA -0.1 1.53 0.7135 0.3 2.19 o.5754 - A-Svert o.7 1.28 0.0346 -0.'r 1.10 0.6971 *** *"* B-Svert 1.7 1.46 0.0002 1.8 1.84 0.0007 ** PogSvert '1.6 1.73 0.0020 1.5 2.26 0.0098 "" *** *"* OJ -3.6 2.06 0.0000 -4.9 2.O1 0.0000 *"* ** OB -2.3 1.56 0.0000 -1.5 1.72 0.0015 RESULTS 113

Table 30 Activator: Means and standard deviations for treatment changes. Soft tissue variables:

Tx. changes MALES FEMALI:S

VARIABLE MEAN SD T prob. MEAN SD T prob.

F.conv 0.5 3.40 0.5680 1.0 2.24 0.0892

N-Lang 4.8 10.14 0.0692 3.3 8.65 0.1 260 ** L-Mfold 13.0 11.05 0.0002 12.8 13.23 0.0007 """ *** *"" Hangle 6.7 4.81 0.0000 6.7 4.19 0.0000

Ls-A 0.1 2.26 0.8168 0.4 1.41 0.3049

Li-B 0.6 3.38 0.4450 0.9 3.22 0.2355

ST TFH 5.0 4.50 0.0003 ""* 4.9 3.16 0.0000 "** . *** ST UFH 1.7 3.30 0.0460 2.5 2.57 0.0007 *"* *** ST LFH 3.0 2.99 0.0008 2.2 2.24 0.0008 * STLFH% -0.1 1.99 0.9034 -0.8 1.60 0.0430 *** *** Ls-E -2.6 1.59 0.0000 -2.6 1.50 0.0000 ** Li-E -1.7 2.34 0.0085 -1.0 2.22 0.0715 * ULL 1.3 1.93 0.0154 0.3 1.29 o.2703 ** *** LLL 3.6 4.06 0.0019 3.6 2.83 0.0000 ** *** STP-STN 4.5 4.74 0.0012 5.1 3.78 0.0000 ** ** Sn-Svert 1.5 2.O3 o.oo72 0.9 1.20 0.0042

SsSvert 0.5 2.19 0.3539 -0.2 1.59 0.6066

LsSvert -0.3 3.16 0.7271 -0.5 1.66 o.2047 ** LiSvert 1.4 2.75 0.0508 1.8 2.46 0.0070 "" *** *** SiSvert 2.8 1.97 0.0000 3.3 2.47 0.0000 *** STPSvert 2.4 2.36 0.0007 2.0 2.75 0.0058 "*

(*) significant at p<0.05

(* *) significant at p<0.01

(*,r *) significant at p<0.001 RESULTS tr4

Table 31 GTB: Means and standard deviations for treatment changes. Hard tissues:

Tx. changes MALES FEMALES

VARIABLE MEAN SD T prob. MEAN SD T prob.

SN-FH -0.1 1.10 0.6019 -0.2 1.10 0.4988

SNA -0.2 1.O7 0.4681 -0.9 1.08 0.0148 "

MaxPl-SN 0.5 1.92 0.3185 0.3 1.39 0.3954 *** Co-A 2.0 1.92 0.0007 -0.1 2.18 0.9018 *** U1-SN -6.4 5.94 0.0004 -7.4 4.91 0.0002 "** *"* U1-NA -6.2 6.23 0.0009 -6.5 4.63 0.0003 "*" ** *" U1-NA(mm) -1.9 2.10 0.0021 -'1.5 1.73 0.0075 *** *** U1-MaxPl -5.9 5.86 0.0008 -7.0 4.93 0.0002 . U1-L1 3.3 6.11 0.0385 3.7 4.91 0.0198 "

LOP -'1.9 2.11 0.0021 "" -2.7 2.77 0.0045 "* *** *** ANB -1.8 1.52 0.0002 -2.0 1.27 0.0001 ** ** L1-NB 4.6 5.48 0.0033 4.9 4.86 0.0035 ** *** L1-NB(mm) 1.5 1.81 0.0035 1.7 1.25 0.0003 ** IMPA 2.8 5.67 0.0592 3.7 4.12 0.0075

L1-MP 0.1 1.31 0.7238 0.1 1.40 0.8932 *** ** SNB 1.6 1.38 0.0003 1.2 1.31 0.0079 *"* Co-Gn 5.5 2.65 0.0000 3.3 2.41 0.0003 "** *** Ar-Gn 4.9 2.80 0.0000 4.3 1.57 0.0000 "** **" Co-Go 3.4 2.19 0.0000 1.7 2.58 0.0322* *** **" Ar-Go 2.9 2.51 0.0002 2.9 2.06 0.0003 *** UFH 1.8 1.59 0.0003 1.1 1.11 0.0044 "* *** *** LFH 2.6 1.25 0.0000 2.2 1.66 0.0004

UFHLFH -0.4 3.07 0.6251 -1.3 3.19 0.1819 *"* N-Me 4.6 2.04 0.0000 3.9 1.61 0.0000 "** *** *** S-Go 3.4 2.38 0.0000 3.0 1.83 0.0001

PFHAFH 0.4 1.42 o.2251 0.5 1.26 0.2167

FMA 0.4 1.90 o.4407 0.3 1.37 o.4740 ** A-Svert 0.9 1.28 0.0076 -0.3 1.60 0.51 16 *** * B-Svert 3.0 2.62 0.0002 1.6 2.41 0.0373 . PogSvert 3.0 2.71 0.0003 ""* 1.5 2.13 0.0294 *** **" OJ -5.0 2.67 0.0000 -5.3 2.77 0.0000 ** OB -2.0 2.13 0.0015 -2.4 1.84 0.0005 "** Rssulrs 115

Table 32 CTB: Means and standard deviations for treatment changes. Soft tissue variables:

Tx. changes MALES FEMALI:S

VARIABLE MEAN SD T prob. MEAN SD T prob. . * F.conv '1.8 2.85 0.0181 1.9 2.30 0.0105 * N-Lang 3.7 5.48 0.0135 4.5 7.54 0.0536 *** L-Mfold 12.7 9.38 0.0000 15.9 9.40 0.0001 "**

Hangle 6.0 4.25 0.0000 "** 7.6 4.77 0.0001 "**

Ls-A o.4 1.64 0.3638 -o.7 1.54 0.1 430 *** * Li-B 2.3 2.20 0.0005 1.6 2.32 0.0319 **" ** ST TFH 4.7 2.46 0.0000 3.9 3.29 0.001 1 *** ST UFH 2.6 1.47 0.0000 2.0 2.38 0.0099 "" *** . ST LFH 1.7 1.70 0.0009 1.4 2.07 0.0289 ** * STLFH% -1.1 1.26 0.0032 -0.9 1.29 0.0323 *** Ls-E -2.1 1.23 0.0000 -2.7 1.48 0.0000 "**

Li-E 0.0 1.25 0.9649 -0.5 1.19 0.1752 * ULL 0.5 1.63 0.2076 0.8 1.23 0.0354 *** LLL 3.4 1.99 0.0000 2.8 1.84 0.0002 ""* *** STP-STN 4.0 3.54 0.0003 3.3 5.52 0.0543 *** Sn-Svert 1.6 1.94 0.0031 0.3 1.49 0.4464 ** SsSvert 1.4 1.76 0.0045 -0.7 1.56 0.1 354 . LsSvert o.7 2.40 0.2765 -1.2 1.72 0.0303 *** LiSvert 4.O 2.60 0.0000 1.7 3.17 0.o778 *** ** SiSvert 5.0 2.74 0.0000 3.0 3.00 0.0040 *** * STPSvert 3.9 3.20 0.0001 2.1 2.97 0.0254

(*) significant at p<0.05

(**) significant at p<0.01

(+**) significant at p<0.001 RBsUI-rs 116

Table 33 Fränkel: Means and standard deviations for treatment changes. Hard tissues

Tx. changes MALES FEMALES

VARIABLE MEAN SD T Prob. MEAN SD T prob.

SN-FH 0.4 1.70 0.3566 0.4 1.52 0.3385

SNA -0.3 1.62 o.4441 -0.5 1.35 0.1 631 . MaxPl-SN o.2 1.77 0.6393 1.3 1.76 0.0166 * Co-A 1.7 3.13 0.0601 1.9 2.70 0.0227 *** *** U1-SN -8.4 6.60 0.0002 -6.5 3.46 0.0000 *"* *** U1-NA -8.1 6.20 0.0002 -6.0 3.48 0.0000 *** U1-NA(mm) -2.5 1.70 0.0001 -2.3 1.55 0.0001 "** **" *** U1-MaxPl -8.2 6.78 0.0004 -5.2 4.O2 0.0003 * U1-L1 5.0 '10.03 0.0722 4.5 5.69 0.01 16 *** LOP -3.2 2.60 0.0003 -0.9 2.04 0.1 059 *** ANB -1.4 0.96 0.0001 -0.9 0.96 0.0032 ""

L1-NB 4.4 6.24 0.0169. 2.4 4.87 0.0841 *** ** L1-NB(mm) 1.7 1.50 0.0006 0.9 1.00 0.0053

IMPA 2.9 6.19 0.0900 1.2 4.65 0.3669

L1-MP o.4 2.54 0.5242 1.9 1.93 0.0032 "* * SNB 1.0 1.49 0.0191 o.4 0.91 0.1284 *** *** Co-Gn 5.'1 4.07 0.0002 4.7 3.73 0.0004 *** Ar-Gn 5.4 2.82 0.0000 4.1 2.49 0.0000 "*" ** Go-Go 3.3 3.38 0.0021 "* 3.1 3.33 0.0040 **" **" Ar-Go 3.5 1.93 0.0000 2.4 2.09 0.0008 *** *"* UFH 2.0 1.76 0.0005 2.4 1.67 0.0001

LFH 3.6 2.45 0.0001 """ 2.9 2.19 0.0003 "*"

UFHLFH -1.4 4.01 0.1 901 -0.1 4.96 o.9292 *** *"' N-Me 5.8 3.03 0.0000 5.4 2.22 0.0000 **o *** S-Go 4.4 2.50 0.0000 3.6 2.68 0.0002

PFHAFH 0.7 1.32 0.0646 0.3 1.80 0.5504

FMA 0.0 1.55 0.9673 0.5 2.32 0.4613 * A-Svert 0.8 1.36 0.0307 o.4 1.35 o.2371 *"* B-Svert 2.3 1.94 0.0005 1.1 1.92 0.0510 ** PogSvert 2.2 2.O5 0.0011 0.8 2.28 o.2257 *** *** OJ -5.1 2.01 0.0000 -3.8 1.18 0.0000 *"* OB -3.1 1.93 0.0000 "** -2.3 1.59 0.0001 RESULTS t17

Table 34 Fränkel : Means and standard deviations for treatment changes. Soft tissue variables:

Tx. changes MALES FEMALES

VARIABLE MEAN SD T prob MEAN SO T prob.

F.conv 1.8 2.49 0.0125. 0.3 1.98 0.5931 ** N-Lang 4.8 4.70 0.0015 2.9 8.61 o.2225 *** *** L-Mfold 16.4 11.33 0.0001 15.2 11.97 0.0004 *"* Hangle 6.9 4.40 0.0000 "*" 6.2 2.90 0.0000

Ls-A 0.0 1.53 o.9274 -0.5 2.15 0.3752 * Li-B 2.0 1.78 0.0006 "** 0.8 1.16 0.0187 *** *** ST TFH 6.4 3.63 0.0000 5.3 3.18 0.0000

ST UFH 3.0 2.06 0.0001 "** 2.9 2.74 0.0018 "* *** ** ST LFH 3.4 2.74 0.0003 2.4 2.74 0.0060

STLFH% -0.5 1.17 0.1 1 07 -0.8 2.34 0.2360 *** *"* Ls-E -2.4 1.50 0.0000 -2.5 1.41 0.0000 ** ** Li-E -1.1 1.36 0.0067 -1.6 1.49 0.0017 *** ULL 1.6 1.31 0.0003 -o.2 2.73 0.8395 *** LLL 4.O 2.95 0.0001 3.4 1.78 0.0000 ""* *** STP-STN 5.3 3.61 0.0001 4.8 2.96 0.0000 ""* *" Sn-Svert 1.7 1.70 0.0021 0.6 3.01 0.4364

SsSvert 1.0 1.90 0.0532 0.1 2.48 0.8560

LsSvert 0.3 2.07 0.6458 -0.4 2.58 0.5888 ** LiSvert 2.7 2.90 0.0030 0.9 2.50 0.1 855 *** 0** SiSvert 4.1 2.02 0.0000 2.8 1.91 0.0001 **n STPSvett 3.5 2.83 0.0003 1.8 2.93 0.0417 "

(*) significant at p<0.05

(**) significant at p<0.01

(r + *¡) significant at p<0.001 RESULTS 118

4.6 SEX COMPARISONS IN TREATMENT CHANGES

Section 4.6 (Table 35) presents a summary of those variables with statistically significant differences in treatment changes between males and females, within each group. Comparisons of the mean differences in males compared to the mean differences in females were made using an unpaired t-test (i.e. the amount of change in males was compared to the amount of change in females). This is presented in tabular form below.

Table 35 Comparison of the changes in craniofacial and soft tissue variables from pre- to post-treatment between males and females.

Signif. c;hanges ACT. CTB. FRÄNKEL.

VARIABLE T-prob. T-prob. T-prob.

Co-A 0.011*

LOP 0.0'l 7* 0.014*

Co-Gn 0.031*

UFH 0.044*

A-Svert 0.050" 0.025*

OJ 0.047*

Li-B 0.045*

ULL 0.035*

SsSvert 0.002**

LsSvert 0.028*

LiSvert 0.034"

Only SsSvert in the Clark Twin Block group reached significance at the p<0.01 level" All the other variables displayed were signihcant at the p<0.05 level.

4.7 COMPARISON OF DIFFERENT APPLIANCES: TWO-WAY ANALYSIS OF VARIANCE

Section 4.7 (Table 36) summarises the results of the two-way analysis of variance (ANOVA) with functional appliance group and gender as factors. These ANOVAs were performed on pre-treatment variables, the post-treatment variables, and on the "differences" calculated over the treatment time. RBsUI-rs t19

Table 36 Two-way Analysis of Variance, with functional appliance groups and sexes as factors. Hard tissue variables.

Significance of F with respect to treatment type and gender, calculated for pre-treatment, post-treatment anã the differences between pre- and post-treatment values. Hard tissue variables:

Significant PRE-TREATMENT POST-TREATMENT DIFFERENCES

Difflces: Group Group Group * * SN-FH 0.034 0.018 * MaxPl-SN 0.038 0.050 ** . Co-A 0.004 0.001 * U1-SN 0.039

U1-NA 0.049 "

U1-NA(mm) 0.024* * ** U,I-L1 0.037 0.006 ** LOP 0.006 ** 0.000 *** 0.003 0.028 "

ANB 0.060 0.055 *" *** L1-NB 0.007 0.000 *** L1-NB(mm) 0.000 ** IMPA 0.002 0.000 "** * * L1-MP 0.026 * 0.008 ** 0.000 "*" 0.016 0.015 ** ** Co-Gn 0.002 0.001 ** Ar-Gn 0.010 * 0.007 ** Co-Go 0.001 "* 0.002

Ar-Go 0.010 * 0.022*

UFH 0.018. ** LFH 0.021 * 0.004 ** 0.032 " 0.003 * UFHLFH 0.016 ** * N-Me 0.002 0.001 ** * S-Go 0.002 0.004 ** A-Svert 0.007 ** 0.001 ** 0.004

B-Svert 0.019 * 0.055 * PogSvert 0.017 " 0.039 * OJ 0.019

OB o.022* Variables SNA, SNB, Ul-MaxPl, PFHAFH and FMA were not associated with significant F-values for either pre-treatment, post-treatment or differences. RESULTS t20

In addition, for the lower occlusal plane there was a significant interaction between sex and treatment type when considering the "differences" group.

Table 37 Two-way Analysis of variance, between functional appliance groups and gender. Soft tissue variables:

Significant PRE-TREATMENT POST-TREATMENT DIFFERENCES

Diffces: Group Group Group . * L-Mfold 0.029 0.010 *" ** *** Ls-A 0.042" 0.006 0.001 0.000 * L¡-B 0.027 ** *** ST TFH 0.001 0.000

ST UFH 0.030. 0.032. ** ** ST LFH 0.003 0.001 * Li-E 0.019 ** ULL 0.001 0.032 " . LLL 0.036 ** ** STP-STN 0.003 0.002 *** *** * Sn-Svert 0.000 0.000 0.019 ** *** SsSvert 0.001 0.000 0.003 "* *** *** LsSvert 0.000 0.000 ** . LiSveft 0.010 " 0.001 0.031

SiSvert 0.015. 0.060 * * STPSvert 0.016 0.030

Soft tissue variables F.conv., N-Lang, H angle, STLFH% and Ls-E yielded no significant F-values in either of the pre-treatment, post-treatment or the differences groups.

An analysis of variance of the pre-treatment measurements indicated only three hard tissue and two soft tissue variables exhibited significant differences among the groups.

The lower occlusal plane, the lower incisor apex to mandibular plane distance and the lower face height were the hard tissue variables while the upper and lower lip thicknesses were the significant soft tissue variables. Rssulrs I2I

The same three combined group and gender variables (L1-MP, LFH, Ls-A) which were significant pre-treatment were also significant post-treatment. Post-treatment Ul-NA, U1-NA(mm), interincisal angle, lower occlusal plane, L1-NB, IMPA, ANB and uppef face height to lower face height ratio were all significantly different between the groups.

Both the angular and linear measures of the upper incisor to the NA-line were significant for the groups. The upper face height to lower face height ratio was also significant between the groups post-treatment, being highest in the Fränkel and lowest in the activator. To some extent this was affected by the selection criterea employed, in addition to growth direction and the treatment response.

Changes between pre- and post-treatment

The changes in skeletal variables such as SNA, SNB, mandibular length and ramus height, were not statistically signif,rcant between the groups. The change in the ANB angle was close to significant with the biggest ANB reduction being detected in the Clark Twin Block (1.9'), then the activator with headgear (1.5') and least in the Fränkel (1.2.).Thus it appears that skeletally the three functional appliance groups basically achieve similar results.

The lower lip to the E-line also exhibited significant changes between the groups during the treatment period.

4.8 COMPARISON OF DIFFERENT APPLIANCES: ONE-WAY ANALYSIS OF VARIANCE

Section 4.8 (Tables 38-40) presents the results of the one-way analysis of variance. Following the two-way ANOVA, a one-way analysis of variance and a Student- Newman-Keuls test was used to determine which groups differed significantly at the p<0.05 level.

Where a significant effect of both treatment group and gender was determined for the variables by the two-way ANOVA, a one-way ANOVA was employed to compare treatment groups for males and females separately. Where there was evidence of significance for a particular variable only for the appliance groups, and not for gender, the data were combined for males and females. The significant differences between the particular functional appliance groups are denoted with an asterisk (*) and are in tabular form below. RssuLrs 122

Table 38 Pre-Treatment One-Way Anova Comparisons:

One-wav Analysis of Variance (Multiple comparisons-Male and females "pooled" Pre-Treatment)- variableê tabuíated were signifiòant \i/ith ANOVA for only group differences i.e. no significant sex difference.

Combined 1úland F Student Nerrman Keuls Test

PRE-TREA]'MENT One-way Analysis of Variance

Variable F prob. 1vs2 1vs3 2vs3 LOP 0.0067 ** Li-B 0.0404* * * 1: Activator-headgear combination 2: Clark Twin Block 3: Fränkel

One-way Analysis of Variance (Multiple comparisons-Male Pre- Treatment)- variables tabulated were significant witti ANOVA i.e. signifÌcant group and sex difference.

Males Student Ner¡rman Keuls Test

PRE-TREA]'MENT One-way Analysis of Variance

Variable F prob 1vs? 1vs3 2vs3

L1-Mp No detection of 2 groups significantly different at the 0.05 level LFH No detection of 2 groups signifìcantly different at the 0.05 level Ls-A No detection of 2 groups significantly different at the 0.05 level

1: Activator-headgear combination 2: Clark Twin Block 3: Fränkel

One-way Analysis of Variance (Multiple comparisons-Female Pre- Treatment)- variables tabulated were significaht witti ANOVA i.e. significant group and sex difference.

Females Student Nermnan Keuls Test

PRE-TREA]'MENT One-way Analysis of Variance

Variable F prob 1vs2 1vs3 2vs3

L1-MP 0.0039 ** * LFH 0.0263 * Ls-A No detection of 2 groups significantly different at the 0.05 level

1: Activator-headgear combination 2: Clark Twin Block 3: Fränkel RBsulrs r23

Table 39 Post-Treatment One-Way Anova Gomparisons

One-wav Analvsis of Variance (Multiple comparisons-Male and females "pooled" Post-Treatment)- variableê tabulated were significant with ANOVA for only group differences i.e. no s¡gn¡t¡cant sex difference.

Gombined lú and F Student Nerrman Keuls Test

POST-TREIITMENT One-way Analysis of Variance

Variable F prob 1vs2 1vs3 2vs3

U1-NA 0.0375 "

U1-NA(mm) 0.0185 " . U1-11 0.0293 *** LOP 0.0002 * ANB 0.0496 ** L1-NB 0.0062

IMPA 0.0003 "**

UFHLFH 0.0207 "

1: Activator-headgear combination 2: Clatk Twin Block 3: Fränkel

One-way Analysis of Variance (Multiple comparisons-Male Post-Treatment)- variables tabulated were significant witti ANOVA i.e. significant group and sex difference.

Males Student Nevwnan Keuls Test

POST-TREIITMENT One-way Analysis of Variance

Variable F prob. lvs2 1vs3 2vs3 L1-MP o.o248" LFH No detection of 2 groups significantly different at the 0.05 level Ls-A No detection of 2 groups signifìcantly different at the 0.05 level 1: Activator-headgear combination 2: Clark Twin Block 3: Fränkel RESULTS r24

One-way Analysis of Variance (Multiple comparisons-Female Post-Treatment)- variables tabulated were siginificant witn ANOVA i.e. significant group and sex difference'

Females Student Neruman Keuls Test

POST.TREITTMENT One-way Analysis of Variance

Variable F prob 1vs2 1vs3 2vs3 *" L1-MP 0.0015 ** LFH 0.0057 ** Ls-A 0.0028

1: Activator-headgear combination 2: Clark Twin Block 3: Fränkel

Table 40 Pre- To Post-Treatment Differences - One-Way Anova Analysis

One-way Analysis of Variance (Multiple comparisons-Males and females "pooled" Differences)- variable3 tabuiated were signifii ant with ANOVA for only group differences i.e. no significant sex difference.

Combined lú and F Student Neruman Keuls Test

DlFFERENC]ES One-way Analysis of Variance

Variable F prob. 1vs2 1vs3 2vs3 u1-L1 0.0050 ** ** L1-NB 0.0004 *** ** L1-NB(mm) 0.0001 *** ** IMPA 0.0003 *** *t L1-MP 0.0190. Li-E 0.0151 * a 1 : Activator-headgear combination 2 Clark Twin Block J Fränkel

One-way Analysis of Variance (Multiple comparisons-Male Differences)- variables tabulated were significaht with ANOVA i.e. signiflcant group and sex difference.

Males Student Nerrman Keuls Test

DIFFERENC;ES One-way Analysis of Variance

Variable F prob 1vs2 1vs3 2vs3 * LOP 0.0456

1: Activator-headgear combination 2: Clark Twin Block 3: Fränkel RBsUI-rs r25

One-way Analysis of Variance (Multiple comparisons-Female Differences)- variables tabulated were significaht witti ANOVA i.e. significant group and sex difference.

Females Student Nerarman Keuls Test

DIFFERENC]ES One-way Analysis of Variance

Variable F prob. 1vs2 1vs3 2vs3 *" LOP 0.0042

1: Activator-headgear combination 2: ClarkTwin Block 3: Fränkel

4.9 COMPARISON TO PUBLISHED CONTROLS

Section 4.9 illustrates a comparison of the cuÍrent investigation to selected published standards of "untreated controls". No significant differences were detected between the ages of the groups. Allowance has been made for the differences in treatment time with respect to the Illing et al. (1998) and Morris et al. (1998) data.

The pre-treatment comparison between the Illing et al. (1998) and Morris et al. (1998) study with the current investigation, determined some statistically significant differences between the groups, Males in the activator group displayed some signif,rcantly different variables pre-treatment. Variables LFH, Ls-A, ST LFH, STLFH%, ULL and LLL had decreased values in the controls while F.conv. and ST UFH were increased post-treatment. In addition, the male activator sub-group had a smaller ANB ( by 1.3") and overjet ( by 2.6mm) than the controls, while B-Svert., LiSvert., and SiSvert were significantly larger than the controls. The male Fränkel group had a 2mm greater overjet pre-treatment when compared to the controls.

The females all had significantly smaller overjets than the controls while ST LFH, STLFH% and LLL were significantly larger. Other significant female differences were present with increased LFH and ULL in the activator group. This increase in lower face height may be expected in patients who would be treated with an activator with headgear. The Clark Twin Block females had decreased F.conv. and Ls-E, while Ls-A was increased. The females in the Fränkel group had increased Ls-A andLLL, while the Ls-E was decreased when compared to the controls. RssuLrs t26

post-treatment, a number of statistically significant differences were detected which were not present pre-treatment. These help to provide more insight into some of the changes which may have occured.

In the Lange et al. (1995) control sample of 30 individuals, genders were combined' Significant differences were detected in numerous variables post-treatment' The ages were similar in all the groups. Treatment time was similar to the activator and the Fränkel but longer than the Clark Twin Block. Even with this decreased observation time in the Clark Twin Block significant differences were detected when changes were compared to the controls. For instance, there was a markedly decreased ANB angle compared to the controls. Unfortunately, pre-treatment data were not supplied in the publication, thus establishment of the suitability of these controls with the current sample is difficult. The changes over the observation period, however, were compared to give an idea of possible changes, which may be significant. Statistical analysis of the changes determined between the groups established numerous significant differences.

Comparison of the present study to published standards can be found in Appendix 8.6'

4.10 PRE. AND POST-TREATMENT COMPOSITE TRACINGS

Section 10 (Figures 19 to 24 ) illustrates pre- and post-treatment composite tracings for each functional appliance group, based on cranial base superimposition. These were generated from calculated average pre- and post-treatment X and Y coordinates for the movements involved with respect to SN-7'. The individual plots in the Appendix (8.7) show that individual variation however, is substantial. RESULTS 727

Figure 19 Activator / Headgear Gomposite Tracing: Males

o

Pre-treatment Post-treatment

Figure 20 Activator / Headgear Composite Tracing: Females

o v Rssurrs t28

Figure 21 Cla¡k Twin Block Gomposite Tracing: Males

o

Pre-treatment Post-treatment

Figure 22 Cla¡k Twin B|ock Gomposite Tracing: Females

o Rssurrs r29

Figure 23 Fränkel Composite Tracing: Males

o

Pre-treatment Post-treatment

Figure 24 FränkelComposite Tracing: Females

o RBsulrs 130

Mean treatment changes, according to cranial base superimposition, for landmarks using SN-7o Cartesian axes can be found in the Appendices (8.a). Each functional appliance is represented in separate tables according to hard and soft tissue landmarks.

The change for each variable was calculated for each individual, and the mean change determined for individual appliance groups. The cephalograms were oriented to the right thus a positive change in the x-axis denotes an anterior movement of the landmark. A positive change in the y-axis indicates superior movement. DISCUSSION 131

5. DISCUSSION

5.I THE SAMPLE

The initial sample consisted of 94 Class II division 1 patients, This was subdivided according to the functional appliance used. The activator with headgear group consisted of 35 consecutively treated patients with full records (17 males and 18 females). The Clark Twin Blocks were employed in 30 patients (17 males and 13 females) while the Fränkel group had 29 patients (15 males and 14 females). The males had an average starting overjet of 8.1mm, with an average pre-treatment ANB angle of 5.9'. The females pre-treatment overjet was 7.4mm, associated with an average ANB of 6".

It is still unclear why such vast variability in Class II correction exists, and why one person is relatively easy to treat whereas another requires much more time and attention (Stockfisch,lgg5).In addition, the changes we were seeking to determine are small in comparison to the variability seen thus alarge sample size is necessary to improve the statistical power (Tulloch et al., 1990), Ideally a slightly larger sample number, evenly divided by gender in each appliance group would have been beneficial in the current study.

5.2 AGE OF PATIENTS

The male patients in the current investigation had a mean age of 10.9 years, with a range of 8.1 to 74.7 years. The females had a mean age of 10.8 years, with a range of 8.0 to 13.8 years.

The activator with headgear subgroup had a mean age of 11.1 years. The males in this group had a mean of lLZ years old, while the females were 11.0 years old.

The Clark Twin Block sample had a mean age of 10.6 years with males exhibiting a mean of 10.7 years and females a 10.5 year mean.

The Fränkel sample consisted of males aged 10.9 years and females 10.7 years, resulting in an average age for the group of 10.8 years. DISCUSSION r32

The ages within and between the groups were quite comparable and allowed determination of the differences which might exist between the appliances. It would have been beneficial to have hand-wrist radiographs, in addition to, height and weight changes over the treatment period. Unfortunately only data on chronological age were available for assessment.

5.3 TREATMENT TIME

Even though completion of treatment was defined in some cases as removal of the functional appliance, with no mention of a retention phase, in other situations it was defined as moving into "night only" wear. A similar finding was found by Ling (1998). Each group was treated by a single operator, thus variations in treatment time were ascribed to factors such as compliance, growth potential, lengths of active versus retention phases andlor retention strategy (Ling, 1998).

The release of the majority of growth hormone occurs nocturnally (Kelch, 1987), thus treatment may be considered to be continuing until the retention phase is complete and the functional appliance is eliminated.

Treatment time actually refers to the time between the initial cephalogram and the end of functional appliance cephalogram. A 90 day "lag time" was allowed from the time of taking the radiograph until the insertion of the specif,rc functional appliance. There was also a 90 day "lead time" allowed during which time the cephaolgram had to be taken following the removal of the appliance. The effect of growth over this "lag time" and "lead time", was thought to be minimal. Most patients were well within the 90 day limits, with a significant number having the final cephalogram on the day of appliance removal. It is not possible to separate the effects of growth from treatment. Thus some of the reported changes will be due to growth (Battagel, 1990). Comparison of the current data to published controls does however provide us with an insight into the treatment changes which occur.

Patients who were required to wear activators and headgear wore them for an average of 610 days. Males had a mean treatment time of 609 days, while females wore them for 610 days.

The Clark Twin Blocks were worn for an average of 465 days, with mean treatment time for males being 473 days and females wearing them for a slightly shorter time frame of 454 days. DISCUSSION 133

The Fränkel was worn for an average of 596 days. Males again exhibiting the longer treatment time at 604 days, while females had the appliance for 588 days. Possible better compliance in females may have decreased their treatment time.

In general, females began treatment a little earlier than males. This is what we would expect from our knowledge of the earlier maturing female (Tanner, 1987).

A significant difference in the treatment time was noted between the Clark Twin Block and the Fränkel, but there was not a significant difference between the times for the Clark Twin Block and the activator. This is probably due to the large variability in these times. In agreement with Morris et al. (1998) the Clark Twin Block appeared to conect malocclusions in a significantly shorter time frame.

5.4 LIMITATIONS OF RETROSPEGTIVE CEPHALOMETRIC STUDIES

Successful functional appliance treatment has been defined often as achievement of overjet reduction andlor molar correction. The development of cephalometrics permitted soft tissue measurement. This allowed analysis of the facial prohle and a more complete evaluation of the soft tissue morphology. Craniofacial growth influences the occlusion and overall facial aesthetics (Prahl-Andersen, 1995). There have been few studies on positive and negative effects of functional appliances on the facial profile. This investigation attempted to evaluate the effect of these three different functional appliances. Retrospective cephalometric studies, howevet, are fraught with numerous limitations (Tulloch et al., 1990). The retrospective procedure is for obvious reasons flawed. We need to appreciate these limitations and work within these boundaries.

Correct diagnosis is important for success. The three orthodontists involved in providing the functional appliances to the patients are all very experienced practitioners.

There is no compensation made for the effect of the operator in the treatment results, thus the total effect of treatment is the result of the specific appliance plus the operator.

The ideal study would be double-blind, randomised, and prospective where we could

standardise the :

o observation period ' aPpliance . compliance (appliance wear)

. operator technique DISCUSSION 134

. design and fabrication o degree of protrusion.

However, Tulloch, Medland and Tuncay (1990) reported 74o/o of research design studies on growth modification of Class II malocclusions are retrospective. Many suffer from poor research designs. Unfortunately, very few prospective studies fulfil the above criteria. Tulloch et al. (7997a,b, 1998) is probably the best known investigation which has attempted to fulf,rl these criteria.

An adequate sample size is required to increase the statistical power of the tests (Battagel, 1993).

Functional appliances attempt to correct a wide range of problems. In actual fact, for an ideal study, we should address only a certain problem, such as, mandibular deficiency, without any other complicating factors in the form of lip habits, digit-sucking, mouth- breathing, or any other functional aberrations (Bishara and Ziaia, 1989).

The subtle appliance design variations within each group and between each group should be considered. Even though every attempt was made to minimise the appliance variation within each group by using a single appliance per operator, certain subtle design features may sometimes occur. A prospective study would allow total control of appliance design (lr{elson et al., 1993).

In addition, the amount of activation and type of activation should be considered (lr{elson et al., 1993). Standardisation of the amount of activation for the overjet present may be crucial in determining treatment results. The amount of mandibular advancement is often different between the activator, Clark Twin Block and Fränkel groups. The Fränkel uses incremental advancements and reactivation procedures of these appliances may have a different effect on "mandibular growth". Correct positioning of labial lip pads as recommended by Fränkel (1983) may also be of paramount importance in the success or failure of the treatment"

Construction bites for appliance fabrication are similar within each of the three functional appliance groups but may vary between groups, depending on the operatot's preference. Different construction bites are often employed with different appliances (Rakosi, 1997a). DISCUSSION 135

Compliance is probably higher with some appliances than with others and very much dependent also on psychosocial factors. The effect of the operator in their ability to motivate the patient and ensure compliance may be paramount. Morris et al. (1998) believes cooperation plays a large role in the individual variation seen in the soft tissue reactions. However, Tulloch et aI. (1997a,b) has shown that compliance may not be as important as once thought in achieving a successful treatment result. In addition, patients who failed to show a positive response are seldom seen for evaluation, either because they discontinued functional appliance therapy or because the orthodontist, in their attempt to correct the situation, changed to another appliance (Tulloch et al., 1990; 1997a). Thus only favourable changes are usually available for study (Creekmore and Radney, 1983; Righellis, 1983). Ideally this selection bias would be overcome with the examination of consecutively treated patients.

It takes markedly longer to adapt to a Fränkel appliance thus patients may not persevere and may discontinue functional appliance therapy. Full time wear may take more than a month from the insertion date, delaying the achievement of the desired response.

Being a retrospective study, centric relation was not recorded for each and every patient' The cephalograms were all obtained in centric occlusion. With a prospective study a leaf gauge could be used to ensure the condyle was correctly seated prior to taking the cephalograms. This becomes especially important in the post-treatment cephalogram, were the patient may very well be posturing forward to some degree. Much of believed "additional growth" may in actual fact be forward posturing of the mandible (Gianelly et a|., 1983). In relation to cranial base reference structures, Buschang and Santos-Pinto (199S) noted articulare showed significantly more inferior movement than condylion. This may be a problem when assessing mandibular growth from articulare rather than condylion.

Young patients are actively growing but exactly where the patients in the present study fall on the growth curve is an unknown entity. Skeletal, dental and chronological age have a low correlation and treatment was not necessarily phased to coincide with maximum skeletal growth rate (Tulloch et al., 1997a;Pancherz,1997).

The growth spurt may occur in children at vastly different times (Hägg et al., 1987; Baumrind, 1987). Fifteen to seventeen percent of adult stature is attained during the adolescent growth spurt (Kelch, 1987). Early and late-maturing individuals exist with DISCUSSION 136

accompanying physical and psychological attributes. Nanda (1955) noted that the spurt appeared to involve the craniofacial skeleton but mandibular growth rates at various stages of development may differ. Thus, within the limitations of the present study, variations were considered only on the basis of chronological age. Harvold and Vargervik (lg7l) determined a close association between statural change and facial growth. Nelson and co-workers (1993) determined a significant increase in mandibular body length in a Harvold activator group when compared to controls. However, when increase in standing height was used as a co-variate in the analysis of the data, the statistical significance was lost. Morris and co-workers (199S) reported a possible trend between standing height measuïes and soft tissue parameters. Unfortunately, the current retrospective investigation lacked standing height measurements over time to allow such an analysis to be Performed.

Once the objectives of overjet reduction, and in most cases molar correction, were obtained the appliances were worn at night only until their use was stopped entirely. The second cephalograms were obtained within 90 days of finishing functional appliance treatment.

The elimination of changes to the soft tissues seen with normal growth has to be considered, so as to determine the "pure" effect of the change induced. These normal growth changes have been reported in the literature (Subtelny, 1959; Vig and Cohen, l97g).In addition, the different sexes and different face types within each sex, are likely to respond in alternative manners because their growth patterns are likely to differ.

The magnitude and direction of growth is also important. These changes may be influenced by later changes that occur with growth as a person ages (Behrents, 1997). Most of the facial changes occur predominantly before the age of 18 years and are sex specific (Behrents, l99l). Longitudinal growth changes in the soft tissues are well- documented (Formby et al., 1994). All these factors are important in determining the long-term post-treatment profile. Ideally, cephalograms should have been taken on the day of appliance insertion and removal. At present there is an inability to confidently discriminate between the effects of growth and the effects of treatment.

There is a need to standardise all cephalograms (Coben, 1979). Standardisation of lip posture should routinely be employed for cephalometric studies. Unconscious lip posture is required, although in the current study there was no definite protocol of evaluating if there was tension in the lips at the time the radiograph was taken. DrscussroN r37

Burstone (1967) and DiCiccio (1993) stated that using cephalograms with the patient's lips at rest and teeth in occlusion gave the most reproducible films and landmarks. Nanda (1998) also stated that it is best to have the lips at rest so as to determine the lips apart posture, to see the lip line, and the amount of incisor show. This is contrary to Holdaway (1983) who prefers cephalograms taken with the lips together so as to determine the lip strain. Ideally, for the present study all cephalograms would of been taken with lips at rest.

Magnification differences between cephalograms provide distortions for linear measurements markedly more than for angular variables. If cephalograms are not standardised, superimposed tracings are often erroneous and misleading (Coben,1979). Patients who had radiographs taken at different institutions such that the radiographs were unable to be superimposed accurately, were deleted from inclusion in the present study sample. Some radiographs had no linear ruler displayed in the midsagittal plane thus an assumption was made of similar magnification of a cephaolgram when taken within the same institution. A standard 120 millimetre head midsagittal / cephalogram film distance may accommodate all head sizes. This would equate to an 8olo universal enlargement (Coben, 1979). In the present study the seven locations where cephalograms were taken all differed in their magnifications and each cephalogram was individually adjusted for magnification and converted to life-size.

Superimposition of radiographs may be associated with considerable error since cranial structures are often difficult to detect as they are obscured by other cranial structures. Reliability of the superimposition is improved by using stable structures (Björk and Skieller, 1983). It is also dependent on the quality of the original radiographs, expertise and care, and the protocol used to record the superimposition (Houston and Lee, 1985). A high speed film with an appropriate filter and a constant midsagittal plane distance should be used. It is necessary to employ adequate instrumentation and surroundings and a quite, darkened room with shielded ambient light is preferred when tracing and superimposing sequential radiographs (Battagel, 1993; Trpkova et al., 1991). In addition, comparison of results from different superimposition techniques may be hazardous (Houston and Lee, 1985). Cephalometrics needs to be used as a true scientific tool and not be abused (Coben, 1979) thus every caution was taken in the present study.

Natural head position is the ideal, such that cephalograms are analysed with respect to the true vertical and the true horizontal. In a retrospective study SN-7' is a better DISCUSSION 138

representation of true horizontal than the sella-nasion line (Burstone et al., 1978; Marcotte, 1981). Frankfort horizontal unfortunately has poor reliability due to the difhculty in localisation of orbitale and anatomic porion, thus contains a " large envelope of error" (Baumrind andErantz, l977a,b). Machine porion should not even be considered due to the massive variability in its radiographic location. This obviously would create poor reliability and increase the eror of the method. The sella-nasion line has both landmarks in the midsagittal plane (Steiner, 1953) and is more reproducible' The orientational problems of using the sella-nasion line are not entirely overcome with the use of SN-7" because individuals at the extreme ends of the anatomical spectrum with steep or flat cranial bases must still be acknowledged as having a distinct influence on the results.

It is extremely difficult to find a perfectly matched pre-treatment sample and bias is often present. In the present investigation bias was present in the selection of the appliances for the individuals. The activator with headgear was often selected by the operator for mesofacial to dolichofacial patients, so as to control the vertical dimension more satisfactorily. This form of bias is also noted in previous prospective studies, even when a control group has been used (Jakobsson, 1967).

Each of the three functional appliance groups were subdivided according to sex, but unforlunately, the sample numbers denied further accurate and meaningful subdivision into subgroups according to face height pattern.

In retrospective studies suitable controls are difficult to find (DeVincenzo et al, 1987). Ethical problems exist and double blind studies are not feasible. Many published standards include a large cross section of patients and are not specific to Class II division 1 patients (Bhatia and Leighton, 1993; Riolo et al., 1974). These are not homogeneous samples. Only 35o/o of the Bhatia and Leighton (1993) sample is Class II division 1. These individuals probably did not grow in the same way, to the same degree, and in the same fashion (Graber, I997b). Mandibular growth rates differ between Class I's and Class II's (Buschang et a1., 1986). Treatment success rates may also differ.

It is important to have a control sample that accurately reflects sex, age, and the relevant skeletal mix of the treatment sample (Zylinski et al., 1992). This is sometimes overlooked (De Vincenzo, 7991).

Even when these considerations are adhered to Q.{elson et aI.,1993; Lange et al., 1995; Courtney et al., 1996; Webster et al., 1996; Illing et a1., 1998; Morris et al., 1998) the DISCUSSION t39

differences in the population and race must also be recognised. Without suitable controls the separation of the treatment effect may be jeopardised (Jakobsson,1967).

Additional problems with cephalometric studies include SNA and SNB angles often used to show changes in skeletal measures. These angles may change with incisor position changes, although no skeletal change occurs (Gianelly et a1., 1984;'Woodside, 1998). In soft tissue analysis it would also be benef,rcial to know the fat / weight change over the period of time involved in the study. These were also limitations encountered in the current study.

In interpretation of the statistics, comparison of group averages may mask the individual cases where marked change was obtained by functional appliance therapy. The graphs presented in the Appendix (8.7) reflect the range of treatment changes seen for selected variables. Additionally, statistically significant but small increases in mandibular growth may not be clinically significant in correction of the malocclusion. Even when results are similar, the interpretation and conclusions drawn by individual operators may differ significantly (Tulloch et aL,1990).

5.5 ERRORS IN CEPHALOMETRICS

The cephalogram is a magnified two-dimensional image of a three-dimensional object (Aelbers and Dermaunt, 1996). Most of the landmarks used in this investigation are in the midsagittal plane to avoid errors of projection. The impact of projection effors can also be minimised by using linear measurements in the midsagittal plane. Angular measures are also somewhat flawed since precision placement of the patient into the cephalometer is difficult (Baumrind and Frantz" lglIb).

Errors in landmark identification maybe due to:

1. lack of edge contrast and sharpness (Baumrind andFranlz, I97la),

2. "noise" due to the superimposition of adjacent structures (Vincent and West, 1987; Hågg et al., 1998),

3. a gradual curvature of an outline, which makes single point landmark location more 'West, awkward (Baumrind and Frantz, 1977a; Vincent and l98l), DrscussloN 140

4. the lack of an accurate descriptive def,rnition of a landmark (Baumrind andFranÍ2, 197la,b: Houston, 1983). This is especially important when comparisons are to be made between studies.

Not all cephalometric landmarks have the same degree of reproducibility (Richardson, 1966; Baumrind andFrantz, l97Ia, lgllb; Mitgard et al., 1974). Each landmark has a characteristic envelope of error (Baumrind and Frantz,IgTla; Midtgfud,1974; Stabrun and Danielsen, 1982; Trpkova et al., 1997: Hågg et à1., 1998). Geometrically constructed points are equally reliable with a similar envelope of emor (Savage et al.,

1 e87).

The distribution of most landmark localisation errors is systematic (Baumrind and Frantz, Iglla ). The current investigation had five landmarks and seven variables, which were statistically significant for their systematic errors. This is greater than one would expect by chance alone. Johnston (1986) traced serial radiographs side by side to ensure landmark identification was constant, however one could argue that this is a form of bias and misrepresents the reliability of landmark identihcation. Midtgård (1974) found little difference in landmark localisation between double determinations performed consecutively compared to those separated by a period of four weeks. The current study had an extended two month period between double determination tracings to ensure elimination of memory bias (Stinups, 1993).

Intraobserver variability tends to be less than interobserver variability with the envelope of error being smaller (Richardson, 1966; Stabrun and Danielsen, 1982; Trpkova et al., 1997). All cephalograms in the current study were traced and digitised by a single operator and accordingly should have decreased systematic errors (Houston, 1983).

Even though the operator had less than two years clinical experience in cephalometric tracing, considered relatively limited by some, Savage and co-workers (1987) noted that experience does not have a statistically significant effect on landmark identification. Yet other researchers show that, to some extent, it is important (Krogman, 1958; Baumrind andFruntz,l97la; Midtgård, 1974; Lau et a1.,I997).In the present study the operator's practice may have changed with his increase in expertise throughout the duration of the project. This may also tend to increase systematic errors (Houston, 1983)" Had a double blind methodology been involved throughout the entire analytic process, systematic errors may have had a smaller contribution (Houston, 1983). DIScUSSION 141

Dahlberg's formula was employed to determine errors in landmark identification, digitisation and mensuration (Dahlberg, 1940). The error between the double determinations may not be complete without accounting for the variance of the landmarks (Midtgård, 1974). Most studies agree with the ranking of reliability of landmark identification, with points such as sella and nasion being consistently better than anterior nasal spine or molar points (Baumrind and Frantz,lgllb; Vincent and West, 1987; iHägg et al., 1998). This was confirmed in the current investigation. Reliability estimates in the current study however did not differ markedly fot "4" and "8" points when compared to sella and nasion. This is in contrast to Midtgärd (197a) who stated that errors were less for sella and nasion. This is of great clinical relevance since many measuïements and superimpositions use sella andlor nasion (Baumrind and Frantz, I97Ia).

Reliability was generally greater in the horizontal axis than the vertical axis for the current study, consistent with previous investigations (Hillesund et al., 1978; Hågg et al., 1998). Some studies have found horizontal axis measurements showed significant variability (Richardson, 1966; Baumrind and FranÍ2, I97Ia; Stabrun and Danielsen, 1982; Vincent and West, I98l). This is in accordance with landmarks menton and soft tissue menton in the current study. Reliability was least for the upper molar point, in the vertical axis, which is in agreement with Vincent and West (1987) and Hågg et al. (1998). This is probably due to "noise" from superimposed images of surrounding teeth (Baumrind and Franiz, l97la). This was also thought to be true of the lower incisor apex, but did not appear true in this investigation. The reliability of the lower incisor apex was determined at 99 .60/o in the x-axis and 99 .lo/o in the y-axis. In accordance with Hågg et al. (1998) the reliability of identifying the upper and lower incisal edges in this study was, as expected, higher than that of the apices. This is due to the superimposition of the surrounding structures in the areas involved.

Since landmarks cannot possibly be estimated without localisation effor, the consequences must be recognised and duly respected. Since the reliability for the upper molar point displayed the poorest results this landmark was not used in the determination of any variables. Computer programs for calculation of linear and angular variables, such as the one used in the current investigation have basically eliminated errors of mensuration (Hettige,7996). The more significant errors are those of landmark identification (Baumrind and Frantz, l97la,b; Midtgård, 1974). Errors on angular and linear variables must not be overlooked (Baumrind and Franfz, 1971b). These may be more clinically relevant than the consideration of the analysis of errors associated with DISCUSSION t42

discrete points (Battagel, 1993). They involve the total method error with the errors of projection and mensuration incorporated. Thus an analysis of errors was performed not only on the "x" and "y" coordinates for the landmarks but also on each linear and angular variable. The errors associated with variables are a computation of the errors of discrete points and, therefore, are expected to be greater (Baumrind and Frantz, l97lb). This was evident in the current investigation'

Lower lip thickness (Li-B) displayed the least reliability of the variables determined (59j%). Being a soft tissue measurement this is not surprising. Landmark identification on ill-defined gradual curves in addition to patient positioning in the cephalostat introduce random errors (Baumrind and Frantz, l97la; Houston, 1983; Vincent and 'West, 1987:Häeg et al., 1998).

Intergroup comparisons with patients and "controls" from other samples are often awkward due to the variable measurement error encountered (Battagel, 1993). The limitations must be acknowledged and respected in the interpretation of the data.

Error analysis should help interpret the results in the light of the magnitude of errors which exist (Houston, 1983).

5.6 SEXUAL DIMORPHISM

Males and females have different craniofacial skeletons with the former generally displaying larger dimensions. Most of the soft tissue growth changes, at the nose, lips, and chin, also suggest sexual dimorphism. Males generally have a greater increase over a larger time span than females (Nanda et al., 1990; Ferrario, Sforza, Miani el a1.,1991). Soft tissue growth appears not to be related to skeletal maturation (Riolo et al., 1987). Late maturers tend to have less soft tissue thickness at most ages (Riolo et al., 1987). 'With respect to the current investigation the differences found between genders pre-and post-treatment within each sub-sample, will be discussed with respect to the specific functional appliance employed.

5.7 THE ACTIVATOR WITH HEADGEAR

The 1930s saw the development of the Andresen activator in Norway, followed by a number of other appliances. The activator reportedly activated the protractor muscles to DISCUSSIoN r43

provide a favourable environment for functionally induced sagittal occlusal correction (Rakosi, I997a).In this investigation changes have been detected in both hard and soft tissues.

5.7.1 HARD TISSUE CHANGES

SKELETAL CHANGES

In general, sexual dimorphism is thought to be expressed by skeletal differences, rather than dento-alveolar. That is, the relative lengths of the cranial base and lengths of the maxilla and mandible differ. The sexes are fairly similar before puberty (Enlow and Hans, 1996), although differences do exist and must be considered appropriately (Luder, 1931). Initial homogeneity of the groups was determined. Pre-treatment, the genders were similar with respect to their skeletal variables. Even though the females were probably more advanced with respect to their skeletal maturity (Kelch, 1987), the males exhibited the larger dimension in ramal length.

Even though the mandibular ramal length continued to increase post-treatment in males it was no longer signif,rcantly different between the genders. This was probably associated with the earlier female growth spurt (Tanner, 1987). Upper face height and A-point to sella vertical however, were significantly larger in males. The 20 skeletal variables measured illustrate the changes which have occurred. The limitations associated with points "4" and "8" as skeletal measures were recognised and with this knowledge the data presented may be truly interpreted.

Changes in SNA over the treatment period did not reach statistical significance for the activator with its combination high-pull headgear. There was a small statistically insignihcant decrease in SNA in both males and females. The headgear appeared to restrict the forward maxillary movement. This finding is in contrast to Gianelly et al. (1934) where over a 28 month period there was a 1.5o decrease in SNA with an extraoral high-pull or cervical-pull appliance treatment. In the present study, there was statistical signif,rcance in the changes associated with SNB. Males had a 1 o increase in the SNB angle, while females had a 1.4o increase over the same time span. This also assisted to reduce the ANB angle, by a proportionately similar degree. In any case, in this age group, the usual amount of growth of the mandible may decrease the ANB DISCUSSION t44

angle by a significant degree. Appropriate "untreated controls" are required to determine the significance of the treatment (DeVincenzo et al.,1987). Studies with suitable control groups have also determined a signif,rcant decrease of the SNA and ANB angles in addition to overjet reduction (Forsberg and Odenrick, 1981)'

The current activatorlheadgear group investigation displayed statistical significance for all the mandibular skeletal measures between the first and second cephalograms. The length of the mandible measured from condylion to gnathion, and articulare to gnathion increased. This increase in articulare to gnathion may be influenced by post-treatment posturing of the mandible (Nelson et al., 1993). Condylion to gnathion increased 4.8mm in the males and 5.6mm in the females. B-point to sella vertical also increased by 1.7mm in males and 1.8mm in females. This may be associated with the larger increase in the SNB angle in females over the studied period. V/ith the knowledge of the earlier maturing female (Tanner, 19S7) it may be of no surprise that the males have yet to reach their full growth potential.

Baumrind et al. (1981) and Mills (19S3) indicated contribution to vertical growth of the famus with the use of the Harvold and Andresen activators respectively.

In the current study, the linear measure condylion to gonion increased significantly more in females than males. This variable was longer in the males pre-treatment.

Condylion to A-point was significantly different for males and females post-treatment, with a 1.9mm and 1,4mm increase respectively. This could be due to condylar growth andlor A-point change. The linear measure of A-point to sella vertical was significant only for males with a 0.7mm increase.

The angle between the maxillary plane and the sella-nasion line increased signif,rcantly only in the males. This indicates downward tipping of the palatal plane anteriorly. This may be associated with the location of the headgear tubes and force application on the activator.

One disadvantage of most orthodontic appliances is their tendency to increase anterior face height. This is usually due to downward and backward rotation of the mandible and/or backward or posterior rotation of the maxilla. If we could control the maxilla from migrating downwards and forwards, autorotation of the mandible may be possible. This would assist in improving the prohle (Stöckli and Teuscher, 1985). DISCUSSION t45

In the vertical dimension, change in total face height was statistically significant in both genders. Increases in total face height were of the order of 5.3mm and 4.7mm in males and females respectively. The increase in upper face height was only statistically signihcant for males, with a mean increase of 2.3mm. The lower face height however, was statistically significant for both genders, with females having a larger increase compared to the males. The ratio of upper face height to lower face height, however, did not change significantly in either gender.

Posterior face height increased 4.lmm in males and 3.6mm in females. This was not of the magnitude to change the posterior face height to anterior face height ratio, nor the Frankfort-mandibular plane angle to a statistically significant degree in either gender. Although insignificant, the males did decrease their Frankfort-mandibular plane angle slightly during the treatment period. The effect of growth helped maintain this relatively stable Frankfort-mandibular plane angle.

Harvold and Vargervik (1971) and later Vargervik and Harvold (1985) had reported a restriction of horizontal maxillary growth. Van Beek (1984) also found a vertical and sagittal restriction. This allows the mandible to outgrow the maxilla and assist in Class II correction (Graber, 1997b; Rakosi, 1997a).

The cranial base superimposition with respect to the SN-7o Carlesian axes, may be helpful in determining actual movement of landmarks.

The present study agrees with Jakobsson (1967), Nielsen (1995) and Tulloch et al. (1997a,b) who have detected restricted forward movement of A-point and anterior nasal spine in the x-axis. The restriction of anterior displacement of the maxilla determines the quality of the skeletal profile (Cura et al,, 1996).In a similar discovery to Stöckli and Teuscher (1985) and Cura et al. (1996) the headgear was unable to entirely restrict the lowering of the palatal plane. They found that minimal changes were observed in the basal structures of the maxilla and maxillary growth continued almost undisturbed despite the headgear (Stöckli and Teuscher, 1985; Cura et al,1996).

The high-pull headgear was said to not tip up the anterior maxillary complex, which would enhance upper incisor protrusion and lip prominence (Graber et al., 1994).

In the current study more restriction was evident in the y-axis at posterior nasal spine than at anterior nasal spine. This produced a rotation of the palatal plane. The force vector of the headgear would need to pass through the centre of resistance of the maxilla and dentition to ensure no rotational component was induced (Graber, 1985,1997b). DISCUSSIoN r46

Luder (1931) determined that genders respond differently to activator treatment with females exhibiting a more downward and backward rotating growth pattern. This may however have been associated with a thinner construction bite used in the two samples.

In general, those patients with a good skeletal pattern at the start of treatment can be expected to attain a good profile with an aesthetic lip balance after treatment (Forsberg and Odenrick, 1981).

In the untreated individual the condyle grew posteriorly and slightly moreso superiorly (Buschang and Santos-Pinto, 1998). In the present study, using a similar superimposition technique, condylion was seen to move posteriorly 1.1 mm in males and 0.9 mm in females in the x-axis, while in the y-axis it moved inferiorly 1.8 mm and 0.2 mm respectively.

DENTAL CHANGES

No gender differences were detected initially apart from the deeper overbite in males. With treatment this was reduced and even though still deeper compared to the females, it was not significantly different post-treatment. Upper incisor uprighting was detected post-treatment. This is in agreement with van Beek (1982, 1984), Altenburger and Ingervall (1998) and Keeling and co-workers (1998). Upper incisor position and angulation was determined by a number of variables. Marked statistical significance was determined for U1-SN, U1-NA(degrees), U1-NA(mm), Ul-MaxPl and U1-L1 in both genders. Females had more proclined upper incisors pre-treatment, and the larger reduction during the treatment interval. Initial mean overjet was 7.8mm, which was reduced to 2.9mm. The males had a similar pre-treatment overjet of 7.6mm, which was reduced to 4mm over the same time period. Thus the females had a 1.3mm better reduotion in overjet which may be partly attributed to the mandibular skeletal contribution"

Overbite reduction was statistically significant for males and females. Overbite was deeper originally in the males, and with treatment reduced 2.3mm in males compared to 1.5mm in females. The final overbite was still deeper in the males, by 0.7mm.

Van Beek (1984) reported the overbite was corrected by inhibiting eruption of lower incisors, intruding upper incisors and extruding lower molars and premolars. The overjet was corrected by upper incisor intrusion, retraction and tipping associated with lower incisor proclination, and distal tipping of the upper canines, premolars and DISCUSSION t47

molars. In addition, restrained upper molar and premolar eruption ensured no occlusal plane tilting and an eventual decrease in facial convexity. Altenburger and Ingervall (1998) however, found no incisor intrusion with the van Beek activator, the Herren activator, nor the activator-headgear combination.

In agreement with Cura et al. (1996) and Keeling et al. (1998), the current study found the lower incisors did not show any statistical difference following treatment with respect to proclination nor protrusion. The lower incisors may procline with functional appliance treatment (Altenburger and Ingervall, 1998) even when they are capped in an attempt to limit labial tipping (van Beek, 1882, 1984; Graber, I997b). Contrary to this, even though not statistically significant, the lower incisor to mandibular plane angle actually decreased with treatment 1.5o in males and 1,4o in females in the present study. This may be due to the influence of the operator, appliance andlor patient selection. Courtney et al. (1996) noted that the addition of incisor capping and/or extraoral force application may prevent or limit lower incisor proclination.

In agreement with Harvold (1974) and in contrast to van Beek (1982 , 1984), the present study found there was an increase in mandibular alveolar height. The lower incisors did present statistical significance with respect to the distance from the apex of the lower incisor to the mandibular plane. There was significance at the p<0.01 level for males and at the p<0.05 level for females and the males gained an additional one millimetre of lower incisor eruption.

The lower occlusal plane was significantly different in the males, with the angle to the mandibular plane decreasing 1.4o due to lower molar eruption, The Class II correction was attained by mainly increasing the alveolar height in the mandible, thus an increase in the face height is inevitable (Harvold and Vargervik, 1971). Lower molar eruption also assists in overbite correction with the headgear-activator combination (van Beek, 1984). This also helps explain the increase in vertical face height.

'With respect to SN-7o Cartesian axes the upper molar moved distally 1.1mm due to the headgear in both sexes. This is in agreement with Keeling et al. (1998). The upper molar also continued to move occlusally 2.6mm in males and2.2mm in females even though the high-pull headgear was present. DrscussroN 148

5.7.2 SOFT TISSUE CHANGES

The pre-treatment labiomental fold was significantly more obtuse in the females. This may be associated with a more marked vertical growth pattern of the female. The males also had a longer upper lip length and the upper lip continued to be more protrusive than in the females.

The labiomental fold angle increased 13o in the males and 1,2.8" in the females. The correction of the Class II malocclusion allowed the lips to acquire a better relationship to each other. This provided the opportunity for the lower lip to uncurl and the labiomental fold to become less acute.

The modified harmony angle increased significantly in both genders, with no significant difference between the males and females pre- or post-treatment. This is probably attributed mainly to soft tissue pogonion moving forward with mandibular growth and somewhat to the retraction of the upper lip with the overjet reduction. The retraction of the upper lip was not statistically significant in considering the linear measure of labrale superius to sella vertical. It did however, decrease slightly with treatment, which contributed to the increase in the modified harmony angle. The harmony angle is important since the increase in chin prominence may increase the relative retrusiveness of the lips, There was a signif,rcant difference in the harmony angle in both the genders, with males showing the larger dimension. This is likely to be due to the more prominent chin development seen in males. Soft tissue pogonion which, was not significantly different between the genders, moved forward considerably, especially in the males. This is in agreement with Forsberg and Odenrick (1981).

Forsberg and Odenrick (1981) also determined there was retrusion of upper and lower lips with activator treatment but there was considerable variability in the antero- posterior position of the lips.

In relation to the E-line, the current investigation found the upper lip retracted 2.6mm in both males and females. This was statistically significant. The retraction of the lower lip to the E-line was only significant in the males. Again the forward position of soft tissue pogonion assisted in the alteration of the E-line in relation to the lips. This decrease in facial convexity and better relationship of the lips improves the profile.

Vig and Cohen (1979) stated that although the lips do not grow much after the age of seven, the lower lip is thought to increase more than the upper. Nanda and co-workers DrscussroN 149

(1990) noted the upper lip continued to grow until 15 years old in males, while stopping much earlier in females. In this study, lower lip length increased significantly in both males and females, while upper lip length increased to a statistically significant level only in the male subgroup.

With linear measures to sella vertical, significant increases were seen in the position of subnasale for both genders. Labrale inferius and sulcus inferius also increased and were signif,rcant at the p<0.01 and p<0.001 level respectively. In the lower lip, no differences were seen between the genders.

In the vertical dimension, there was a statistically significant increase in the soft tissue total face height. This was mainly due to the lower face height contribution in the males. There was a significant increase in the upper face height in the females and to a lesser extent in the males. Pre-treatment males had statistically significantly larger soft tissue total and upper face heights, when compared to the females. This was not evident following the treatment. As expected, soft tissue nasion to soft tissue pogonion also was statistically different between the genders pre-treatment, yet not following treatment. The effect of the activator with high-pull headgear appears to make the genders more alike.

Other non-significant trends included:

1. Facial convexity decreased slightly with treatment, more-so in the females. Females had similar facial convexity to the males pre-treatment and became 0.5" less convex with treatment.

2. Changes in the soft tissues are the least predictable. Often they do not follow the hard tissues on a one to one ratio (Owen, 1986; Battagel, 1990)" The nasolabial angle was similar pre-treatment between the genders. It increased with the retroclination of the upper incisors. Even though the upper incisors uprighted more in the females, the nasolabial angle was greater in the males post-treatment.

Along with the labiomental fold, the nasolabial angle had the largest standard deviation of all the hard and soft tissue variables. Post-treatment the standard deviation was decreased suggesting a decrease in the variability of these two variables. DISCUSSIoN 150

3. Upper and lower lip thickness did not change significantly even with retraction of the upper incisors. Mean lip thickness did however increase slightly more in the female. There was however inconsistency in lip posture and uncertainty regarding the lip strain influence.

4, Changes to linear measurements from sella vertical to sulcus superius and labrale superius showed no statistical significance for either gender. Both these measures were, however, statistically different between males and females before treatment, with the males showing larger dimensions.

In summary the changes in the activator group: o had no major effect on the SNA angle.

. increased mandibular length, ramal length and the SNB angle. This was more in the females, however not to such an extent as to allow statistical significance between genders.

. decreased the ANB angle. o tipped the palatal plane; lowering it more anteriorly than posteriorly due to the headgear. There was no maxillary advancement in a horizontal direction. o lower face height increased with no significant change of the FMA.

. upper incisors uprighted with no significant change in lower incisor proclination. Some non-statistically significant retroclination \ryas evident in the lower incisors. This may have been associated with the capping of the lower incisors.

o allowed lower incisor eruption.

o reduced the overjet.

o more retraction was evident in the upper lip than the lower lip with respect to the E- line. This however may have been influenced by more nose growth than chin growth.

o allowed the lower lip to become more protrusive yet with respect to the E-line lower lip retraction \ilas only evident in males due to continued nose and chin growth. DISCUSSION 151

5.8 THE CLARK TWIN BLOCK

The Clark Twin Block is a recent addition to the family of functional appliances and has created great interest (Clark, 1982). This is due to its unique design, which improves comfort, aesthetics and possibly even effrcacy. This may be because of the increased acceptance, motivation and cooperation established (Clark, 1988, 1995 , 1997). However little scientific evidence regarding its effrcacy has been published.

5.8.1 HARD TISSUE CHANGES

SKELETAL CHANGES

Pre-treatment gender comparisons revealed three statistically significant skeletal differences. Total anterior face height would be expected to differ with males displaying larger dimensions (Lund and Sandler, 1998). Post-treatment, the variables for mandibular length (Ar-Gn) and total anterior face height O{-Me) were again significant. In addition, upper and lower face heights became significant. True ramus height (Co- Go), true mandibular length (Co-Gn) and maxillary length (Co-A) also displayed signif,rcant difference between males and females. The dimension of each significant variable was increased in the males. It should also be noted that even though the mean treatment time was slightly shorter in the females, by 19 days, the variations in size are often secondary to normal sexual dimorphism.

King and co-workers (1990) note that patients with milder forms of facial disfigurement, like some malocclusions, suffer more psychological stress because they have not developed coping mechanisms against erratic, inconsistent teasing and ridicule. Individuals with poor facial aesthetics usually have more convex faces (Cox and van der Linden,197I; Czarnecki et al., 1993; Romani et al., 1993; Ferrario, Sforza, Miani et al., 1997).In this study the Clark Twin Block was the most efficient functional appliance at reducing facial convexity, thus making these individuals more aesthetically pleasing. Other appliances struggle to achieve the pronounced orthopaedic growth rate which is demonstrated with this appliance (DeVincenzo, l99l). Possibly the full-time wear, even when eating, may produce more orthopaedic change (DeVincenzo et al, 1987). DISCUSSION t52

In the current investigation there were statistically significant decreases in the ANB angle with treatment. This was in the order of 1.8o in males and2" in females. This is in agreement with Clark (7982), Lund and Sandler (1998) and Illing et al. (1998). Over a nine month period Illing and co-workers (1998) found a2" decrease in the ANB angle. This was significantly different to their matched untreated control group. In the present study, the ANB decrease was partly due to the significant increases in the SNB angle, especially in the males (1.6'). The linear distance of pogonion and B-point to sella vertical increased dramatically in the males (3mm) and less so in the females (1.5mm). The females however also had a significant decrease in the SNA angle (0.9'), which the males failed to display. The restriction of maxillary growth in females, and the accelerated mandibular growth in males has been previously suggested (Ling, 1998). Lund and Sandler (1998) however, found no statistically significant restraint of maxillary growth and no headgear effect associated with this form of functional appliance therapy. This is in contrast to Illing et al. (1998) who reported a 1.4" decrease in the SNA angle with the use of the Twin Blocks. However, no significant sex difference was detected in her study. Gianelly et al. (1984) has warned that fifty percent of the SNA response represents tooth movement, for A-point is actually a deep dento- alveolar point. Nevertheless, midface restriction is an important feature of Class II correction (Harvold and Vargervik, 1971; Pancherz, 1979; Vargervik and Harvold,

1 985 ; Windmiller, 1993).

In actual fact in the current study the maxillary length (Co-A) continued to increase significantly only in the males (2mm). This measurement is determined not only by maxillary growth, but also changes at condylion and the glenoid fossa. Some increase in maxillary length however, was verified by the statistically significant increase (0.9mm) in the linear distance of A-point to sella vertical.

As would be expected in this age group mandibular growth is displayed in both genders. Ramus height (Ar-Go) and mandibular length (Ar-Gn), which can be affected by mandibular posturing (Nelson et al., 1993), in addition to true mandibular length increased by a statistically significant amount. This was displayed in both genders. True mandibular length increased 5.5mm in the males and 3.3mm in the females. Ling (1998) reported a4.9mm increase in males and a 4.5mm increase in females in this variable, over a comparable time frame. Illing et al. (1998) determined a 4.5mm increase in males and a 32mm in females, over a nine month period. The measure for mandibular length (Ar-Gn) was increased in this study by l.1mm when compared to the true mandibular length for the females, This indicates possible posturing of the mandible and the danger DISCUSSION 153

of employing articulare in such measures. This has also been reported by Ling (1998) with his research on the Clark Twin Block. This posturing probably affected the soft tissue measuÍes and longer-term follow-up may reveal noticeable changes in the profile'

In agreement with Clark (1988, 1995), true ramus height (Co-Go) was significantly larger post-treatment. This marked increase is in agreement with Trenouth (1989) and DeVincenzo (1991). Possibly this better tolerated appliance, which allows full-time wear, provides the most favourable biological response. This however may only be an acceleration of desired growth, with no significant difference in the long-term (DeVincenzo, 1991). In agreement with DeVincenzo and co-workers (1987) this increase may not occur in every individual. The graphs displayed in the Appendix (8.7) present the range of treatment changes observed. In the present study, the post-treatment cephalogram revealed there was a l.7mm increase in the females compared to a 3.4mm in males. This illustrates a signif,rcant difference between the males and females post- treatment in this variable. A closer examination of the results shows the posturing in the females affected the results with respect to this variable also. The increase in ramus height (Ar-Go) over the treatment period was 1 .2mm greater than true ramus height (Co-Go).

The vertical dimension may be expected to increase with the use of the Clark Twin Block (Clark, 1995; Lund and Sandler, 199S). Total face height increased significantly in both genders, yet in contrast to DeVincenzo (1991) and Ling (1998) no signif,rcant change was detected in the Frankfort horizontal to mandibular plane angle. Petrovic (1984) found different responses, in the rat, depending on the functional appliance used. In the current investigation the upper and lower face heights increased 1.7mm and 2.6mm respectively in males, while females displayed a 1.lmm and2.2mm increase. There was hardly any change in the upper to lower face height ratio. Illing et al. (1998) reported a 2.7mm increase in lower face height and a total face height increase of 3.8mm in males and 4.3mm in females,

The posterior to anterior face height ratio also failed to change signifrcantly. Posterior face height increased dramatically to be statistically significant in both genders. Males displayed a3.4mmincrease while females had a 3mm increase. This probably accounts for the lack of change of the mandibular plane angle. Possibly the positioning of an anterior fulcrum with the construction of the Clark twin blocks assisted in the up and forward growth of the mandible. However, initial sample selection criteria may have biased the results.

Ultimately the patients' responses are related back to their growth pattern (Clark, 1982) DISCUSSION t54

The dento-alveolar response to the functional appliance treatment is inversly related back to the compensatory skeletal change (Clark, 1982).

DENTAL CHANGES

Only one significant difference was present between males and females pre-and post- treatment. The lower incisor to mandibular plane distance was increased in males. It showed no significant change in either gender over the treatment period and remained significantly different post-treatment. The dental changes were generally similar between the genders.

The upper incisors uprighted signif,rcantly over the treatment period as discussed by Clark (1995), Ling (1998) and Lund and Sandler (1998). In the curent study the mean angulation of the upper incisor to the sella-nasion line was 109' in males and 107o in females. The magnitude of retroclination was in the order of 6.4" and 7 .4" , respectively. In relation to the NA line the retroclination was determined as 6.2" and 6.5o respectively. This greater retroclination seen among the females was also suggested by Ling (1998). In contrast, the Illing et al. (1998) control group demonstrated minor upper incisor proclination over a nine month period.

In females there was significant lower incisors proclination with respect to the mandibular plane angle. This was of the magnitude of 3.7" .It is interesting to note, that the males also had associated proclination with treatment, in the order of 2.8o. This was not determined to be statistically signif,rcant. Ling (1998) reported mean changes in this variable as 3.4o in males and 4.5o in females. Both samples appear to have not only greater upper incisor retroclination, but also greater lower incisor proclination in the females. Clark (1988) reported lower incisor proclination in the active phase and then uprighting in the support phase, with a mean decrease of less than 1o post-treatment.

Inrelationto theNB line, lower incisors proclined 4.6" in males and4.9" in females. They also became 1.5mm and 1.7mm more protrusive, respectively. This protrusion was signihcant at the p<0.001 level for the females. The more marked upper incisor retroclination compared to the lower incisor proclination is in agreement with Lund and Sandler (1998). This increased the interincisal angle such that significant change was determined for both genders. This increase in the interincisal angle is in agreement with Clark (1995) and in contrast to DISCUSSIoN 155

Ling (1998). In the present study the mean post-treatment values of 128' for males and 130o for females approximate the Class I norm of 130' (Ricketts, 1960).

Overjet reduction was a means of assessing success of functional appliance treatment. It was statistically significant at the p<0.001 level. Males exhibited an initial mean overjet of 8.5mm and females 8.3mm. Post-treatment these were reduced to 3.4mm and 2.9mm, respectively. The male 5mm, and female 5.3mm overjet reduction was due to the combination of skeletal and dental changes discussed. Ling (1998) in a similar study where the initial overjets were 7.3mm and 7.2 mm reported an overjet reduction of 4.5mm in the males and 4.7mm in the females, respectively. Lund and Sandler (1998) reported a meaî overjet reduction of 7.5mm, while Illing et al. (1998) determined a 5.7mm reduction over a nine month period. This was significantly different from her controls, who exhibited a 0.7mm increase in overjet.

Overbite was also reduced significantly, especially in the females. The overbite was initially 5.3mm in the males and 4.8mm in the females. A2mm overbite reduction in males and 2.4mm in females was detected. Post-treatment, the males continued to exhibit the deeper overbite. This was similar to the activator I headgear result investigated in the present study. Ling (1998) reported a change in overbite being of the magnitude of 3.7mm in males and 2.8mm in females, however the initial overbite was markedly deeper in his sample. Males in both samples exhibited the greater overbite reduction yet continued to exhibit a deeper overbite. This effect of gender is in contrast to the results of Illing et al. (1998),

As expected with this appliance the lower occlusal plane changed significantly through treatment. Upward and forward eruption of the lower molars assisted in decreasing the angle of the lower occlusal plane to the mandibular plane by 1.9' in the males and 2.J" in the females. This assisted the Class II correction.

'With respect to the SN-7' Cartesian axes, the upper molar moved distally in both sexes. It was 0.2mm in the males and 0.7mm in the females. This is confirmed by Lund and Sandler (1998). This was not of the same magnitude as the activator with headgear reported in the current study. In the x-axis, the lower molar moved mesially 2.2mm in the males and2.4mm in the females. The combination of skeletal and dental movements assisted in correction of the Class II component, DISCUSSION 156

In agreement with Ling (1998):

1. Upper incisors were retroclined to a greater degree with treatment.

2. Lower incisors were proclined to a greater degree with treatment.

3. Overbite was reduced.

The greater the dental result, the less likely the post-treatment result will relapse (DeVincenzo,Iggl). Good intercuspation is benef,rcial for stability (Pancherz, 1997).

5.8.2 SOFT TISSUE CHANGES

Statistically significant pre-treatment soft tissue variables all increased their level of significance post-treatment. Other statistically significant differences were evident post- treatment, with the males displaying the larger dimensions. These were for upper lip thickness and a number of linear lip measures to sella vertical (subnasale, sulcus superius, labrale superius, labrale inferius). These differences were later confirmed with the employment of analysis of variance to determine differences between appliance groups and sex. These findings indicated that males had more protrusive lips post- treatment. Morris et al. (1998) found boys to be more protrusive than females pre- treatment however his male sample was one year older compared to the males in the cunent Clark Twin Block sample. The effect of normal growth and development must be acknowledged and the appreciation of the combined effects with treatment affecting the results.

The angle representing facial convexity increased significantly during the treatment period; 1.8'in males and 1.9o in females. This was not unexpected considering the 1.9" and 2" decrease in the ANB angle respectively. Morris et al. (1998) reported only an insignificant 0.8o increase in facial convexity over a nine month period. The modified harmony angle would also be expected to increase. This was in the order of 6o in males and J.6" in females. This was partly due to soft tissue pogonion moving forward, as indicated by its linear measure to sella vertical. This was in the order of 3.9mm in the males. In addition, there was an associated significant decrease in the upper lip protrusion in the females. Only minimal non-significant increase in the upper lip protrusion was detected in the males. Morris and co-workers (1998) reported no statistically signihcant change in the upper lip even with marked upper incisor retraction. The lower lip moved forward 3.8mm compared to 4mm in the current study. DISCUSSIoN ts7

The females failed to show significant change in labrale inferius. Sulcus inferius displayed a 3mm forward projection in relation to the sella vertical reference line. This has the effect of making the labiomental fold more obtuse. The lower lip appears to move upwards and forwards with overjet reduction (Morris et al., 1998).

The upper lip moved distal to the E-line 2.7mm in males and2.7mm in females, while the lower lip exhibited no signihcant change to this reference line. Moris et al. (1998) also reported only a change in the upper lip, and only in females. This E-line as a reference line is obviously dependant on nose and chin growth. Normally both lips become more retrusive, especially in males, as the nose and chin increase in size (Genecov et al., 1990).

Lower lip thickness increased2.3mm in males and 1.6mm in females, whereas upper lip thickness displayed no significant change. Morris and co-workers (1998), with genders combined, determined the lower lip increase was of the magnitude of 2.lmm. The upper lip thickness failed to proportionally change with the overjet reduction as suggested by Wisth (1974). Pre-treatment lip position and the complex anatomy of the upper lip determine the response observed (Talass et al., 1987).

Lower lip length increased significantly, This was in the order of 3.4mm in males and 2.8mm in females. The upper lip length was only significantly longer in the females post-treatment. Morris et al. (1998) reported a 4mm increase in lower lip length and no significant increase in the upper lip length.

A natural lip seal is automatically obtained for deglutition without exercises with the use of the Clark Twin Block (Clark, 1988). This lip seal is maintained and an improved profile is evident very early into the treatment. This may encourage patient motivation (Clark, 1998).

The hard and soft tissue changes described affect the nasolabial angle and the labiomental fold. The nasolabial angle increased 3.7" in the males and 4.5o in the females, but only the change in the males was signihcant. The female change was close to significant. Morris and co-workers (1998) reported a3.9" increase in this variable over a nine month observation period. DISCUSSIoN 158

Males displayed a12.7" and females a 15.9o opening up of the labiomental fold with treatment. No sex difference was displayed with respect to the change of the labiomental fold in the Twin Block sample of Morris et al. (1998), and with genders combined a 12.7" increase was detected. With the assistance of the functional appliance, lip function may have been corrected and any lip traps eliminated, uncurling the lower lip. In addition, the differential forward growth of the mandible compared to the maxillary complex may also play avital role.

In the soft tissue vertical dimension, females displayed significant increases in all variables except soft tissue nasion to soft tissue pogonion. This variable came close to reaching statistical significance. Males displayed a more significant change for all variables. Morris and co-workers (1998) also reported significant increases in all these variables.

In summary, the Clark Twin Blocks produced the following changes: o SNA decreased in females. In males the maxillary length continued to increase. o SNB increased, especially in males however, not to such an extent as to allow statistical significance between genders. o ANB decreased.

. mandibular length and ramal length increased, especially in males.

o face height increased without a significant increase in the FMA.

o upper incisors uprighted, especially in females however not to such an extent as to allow statistical signifi cance between genders.

o lower incisors became more proclined and protruded, especially in females but not to such an extent as to allow statistical significance between genders.

o the interincisal angle was increased.

. overbite and overjet were greatly reduced.

o the lower molar erupted up and forward to assist Class II correction.

. facial convexity decreased.

. lips became more retrusive with growth of the nose and chin.

o the labiomental fold became more obtuse. DrscussloN 159

o the nasolabial angle significantly increased only in males yet the overjet was reduced markedly in both genders.

Stability may depend on the patients ability to adapt to a new homeostatic state (DeVincenzo, l99l).

5.9 THE FRANKEL

The function regulator was developed by Fränkel according to " functional orthopaedic" principles expounded by Roux (1395) (McNamara and Brudon, 1993; Stockfisch, lees).

Numerous investigations on this appliance have been performed by previous operators (Robertson, 1983; Gianelly et al., 1984; McNamara et al., 1985; Nelson et al., 1993; Courtney et al., 7996; Ghafari et al., 1998).

The initial effect of the Fränkel is thought to be on the soft tissues and with retraining of the oral musculature unrestricted development of the dentition occurs (McNamara and Brudon, 1993). The long term effects have been reported to be remarkably stable (Fränkel, 1983). This may be due to the gradual, progressive muscle retraining and step by step displacement of the mandible (Fränkel, 1983).

5.9.1 HARD TI^S^SUES CHANGES

SKELETAL CHANGES

True ramal height, lower face height and A-point to sella vertical were significantly larger in the males pre-treatment. These variables also all differed post-treatment between the genders. In addition, ramus height (Ar-Go) and the upper to lower face height ratio became significant post-treatment. The angle between the maxillary plane and the sella-nasion line became significantly larger with treatment in females. The constructed composite tracings show a definite anterior tilting of the maxillary plane, which is not evident in the males post-treatment. Posterior face height was tending towards significance initially, and achieved signihcance post-treatment. True mandibular length was also almost statistically DrscussloN 160

significantly different between the genders initially. However, this possible difference did not reach significance during treatment.

Differential tilting of the palatal plane ,ù/as seen in the female, lowering more anteriorly than posteriorly. This is visible on the composite tracings. Maxillary length only increased significantly in the female (1.9mm), whereas A-point to sella vertical reported significant increases only in males (0.8mm). Since maxillary length is dependant on condylion and A-point, changes in this variable may be attributed to growth, remodeling or postural changes.

Gianelly et al. (1984) reported an annualised increase of 3.1mm in mandibular length measured from articulare to gnathion. True mandibular length measured condylion to gnathion, increased 5.1mm in the males and 4.7mm in the females over the current treatment period. This was also apparent with the measurements for mandibular length. Ramal height and true ramal height also increased significantly, being slightly more in the males. Posterior face height increased markedly more than the ramal heights. This is basically due to growth of the cranium with dimensional increases in the distance between sella and condylion. Any possible fossa adaptation could not be accurately assessed.

McNamara (1982) has observed mandibular growth due to the Fränkel of I.2 millimetres per year with forward displacement of B point and pogonion (Bishara and Ziaja,1989).

In the present study B-point and pogonion to sella vertical increased significantly only in males, 2.3mm and 2.2mm respectively. However, the change in B-point to sella vertical, being 1.1mm, approached significant levels in the female.

In the studies of Creekmore and Radney (1983) and Gianelly et al. (1984), SNB increased 0.6o. Battagel (1990) reported a 1o increase and Ghafari et al. (1998) reported a l.4 increase in the SNB angle. Perillo et al. (1996) reported a 0.8o increase per year during the treatment period, slowing down to 0.2mm per year after treatment. In the present study the change in SNB was statistically significant only in the male (1').

No statistical signif,rcance was determined in either gender for the SNA angle within the current Fränkel investigation. Even though not statistically significant, the SNA angle did decrease very slightly (0.3' in males and 0.5o in females). This is in agreement with Creekmore and Radney (1983), Robertson (1983), Gianelly et al. (1984) and Battagel DrscussroN 161

(1990). In comparison to Jakobsson (1967) and Ghafari (1998), evidence of maxillary orthopaedic change was not concluded by Righellis (1983), Bishara andZiaja (1989), or by Courtney and co-workers (1996). McNamara et al. (1985) and Perillo et al. (1996) determined no significant effect on maxillary structures. However, a change in A point due to the change in the underlying maxillary incisors was noted. This was also discussed by Gianelly et al. (1984). Other investigators such as Creekmore and Radney (1983) in addition to Graber (1997a), may have interpreted this same feature as a decrease in forward growth of the maxilla.

The ANB angle decreased 1.4' in the male and 0.9o in the female. This was statistically significant at the p<0.001 and p<0.01 level respectively. Battagel (1990) also reported a 1.5" decrease in the ANB angle over a slightly longer time frame. Perillo et al. (1996) reported a 1o decrease in the ANB angle per year during the treatment phase. This was an annual 0.8o greater decrease in the ANB compared to his controls.

In the vertical dimension, total, upper and lower face heights increased significantly without a change in the upper to lower face height ratio. In addition, an insignificant minimal change in the mandibular plane angle agrees with Robertson (1983), Gianelly et al. (1984), McNamara (1985) and Ghafari et al. (1998).

DENTAL CHANGES

Initial differences between genders were detected in the lower occlusal plane, the distance of the lower incisor apex to the mandibular plane and the overjet. The lower occlusal plane was 2o greater and the lower incisor apex to the mandibular plane was 2mm longer in the males. The pre-treatment overjet was 8.2 in the males and 6.2 in the females.

Post-treatment there was no significant difference between genders. The overjet was reduced to 3.lmm in males and2.3mm in females. With consideration of the Cartesian axes method of overjet measurement for this investigation, the clinical overjet observed would be obviously less than the figures stated above. The clinical overjet is dependant on the thickness of the palatal surface of the upper incisor and the labial thickness of the lower incisor. Thus the clinical overjet at the end of treatment is actually minimal in all appliance groups. DrscussroN r62

Maxillary incisor retroclination is evident (Creekmore and Radney, 1983; McNamara et a1., 1985; Ghafari et al., 1998). All variables for upper incisors indicated significant retroclination, in the vicinity of approximately 8o for males and 6o for females. Lower incisors were significantly more protruded, especially in males. This may be explained in the B-point changes. In agreement with McNamara (1985) they were not significantly 'With proclined in relation to the mandibular plane. respect to the NB-line only males displayed statistical significance with a 4.4" proclination. This protrusion, and only mild proclination may be due to the effect of the labial lip pads. Restricting the muscle forces on the apical area of the teeth may allow them to move forward bodily, rather than just procline. 'With correct design of the Fränkel, no lower incisor flaring (Fränkel, 1984; Nielsen, 19S4) and decreased incisor proclination (Creekmore and Radney, 1983; McNamara et al., 1985) are seen. Others authors, however, have reported lower incisor proclination (Ghafari et al., 1998).

In females the distance of the lower incisor apex to the mandibular plane increased by 1.9mm. For some unexplained reason this was markedly more than the insignificant change in the males of 0.4mm.

With lower molar eruption the lower occlusal plane decreased 3.3' in the males, yet not signif,rcantly changing in the females. This may be explained by the increase in lower incisor eruption detected in the females.

McNamara et al. (1985) reported the restriction of the horizontal movement but not of vertical movement of the upper molar. In the present study the upper molar moved forward along the x-axis 0.6mm in the males and 0.24mm in the females. Marked restriction was not evident in the y-axis and the upper molar continued to erupt to some extent. In view of the error study and the low reproducibility of this landmark, the above statement needs to be interpreted with caution.

Determination of the lower molar was more reliable and in agreement with McNamara et al. (1985). It was seen to move forward along the x-axis 3.7mm in males and 2.8mm in females in an attempt to correct the Class II situation. DISCUSSIoN 163

5.9.2 SOFT TISSUE CHANGES

V/olff s Law states the stress placed on a bone by the musculature determines its shape and structure (Woodside et a1., 1983). Trabeculae are arranged so as to resist stress.

The initial effects of the Fränkel appliance are on the soft tissues and it restrains the musculature but allows unrestricted development of the dentition (Graber, 1997a).

A lip trap may impede forward development of the mandible as it would be restrained. A functional appliance would also allow the creation of a lip seal, which may also increase the force to the upper arch (Isaacson et a1., 1990). Thus a dental effect can also be expected.

The pre-treatment soft tissue gender differences in the present investigation were only for the upper lip. They included upper lip thickness and a few upper lip measures to sella vertical (subnasale, sulcus superius, labrale superius).

These were also all significantly different between the genders post-treatment. In addition, labrale inferius to the sella-vertical reference line was significantly increased in the males during treatment. The upper lip length in males also increased during the treatment period and thus enabled statistical significance to be determined between the genders post-treatment.

Facial convexity decreased in males which corresponds to the greater decrease in the ANB angle found in this sex. Nielsen (198a) however reported that 70Yo show no change in facial convexity. The modified harmony angle increased signif,rcantly in both genders. This is due to the marked increase in the x-axis of soft tissue pogonion, especially in males. This is in association with the fact that labrale superius failed to demonstrate any signif,rcant change.

This change in soft tissue pogonion and the continued growth of the nose affects the E- line. The relationship of the upper lip to the E-line changed during treatment, being retracted 2.5mm. This is in contrast to Owen (1986) who reports that the upper lip tends to come forward with overjet correction, even though the maxillary incisors are retracted. In the current investigation the lower lip retracted 1.lmm in males and 1.6mm in females. DrscussroN r64

Most soft tissue growth has been said to be completed by 12 years old in the female while it continues in the male (Genecov et a1.,1,990).

Lower lip thickness significantly increased, especially in males (2mm). The increase, even though significant in females was only 0.8mm. This may possibly be due to the fact that males mature later and lip growth is detected for much longer (Nanda et al., 1ee0).

Upper lip thickness displayed no significant change during the treatment period. V/ith age it is thought to decrease in thickness while the lower lip increases.

Upper lip length did increase significantly in males (1.6mm), while lower lip length increased in males (4mm) and females (3.4mm).

Battagel (1990) reported very small lip movement in relation to the amount of incisor retraction with no correlation found between the hard tissue changes and the changes in the labiomental fold or nasolabial angle. Owen (1986) remarks that the nasolabial angle does not change much at all with the Fränkel. However, in the current investigation soft tissue changes had an effect in increasing the nasolabial angle 4.8' in the males, yet in agreement with Owen (1986) not signif,rcantly changing it in the females. In the males, subnasale also moved forward significantly in relation to the sella-vertical reference line, whereas evidence of this was lacking in the females.

Possibly the relationship between the hard and soft tissues is too complex to assign a simple ratio (Owen, 1986) and examine it in such a simple way (Battagel, 1990).

The labiomental fold became more obtuse, changing a dramatic, 16.4" in males and I5.2" in females. Battagel (1990) also reported a 12.7o increase. The following significant changes determined the changes in the labiomental fold. Labrale inferius to sella-vertical increased2.Tmm in males. Sulcus inferius increased 4.1mm in males and 2.8mm in females relative to the sella-vertical reference plane. In addition, soft tissue pogonion moved forward 3.6mm in males and 1.8mm in the females.

With respect to the vertical dimension statistical signif,rcance was evident in all related variables for both genders, but especially the males. The soft tissue lower face height percentage did not change in either gender.

In summary, the Fränkel appliance may assist in the provision of the following changes whioh were detected: DrscussroN 165

. no significant change in the SNA angle. However, a small insignificant decrease was noted. o SNB increased in males o ANB decreased o the palatal plane was tilted down anteriorly in females

. mandibular length and ramal height increased

. upper, lower and total face heights increased with no increase in the FMA

. upper incisors were retroclined o lower incisors were protruded, especially in males, but not to such an extent as to

allow stati stical si gnificance between genders o no statistically significant effect on lower incisor proclination was detected, except in males where they proclined 4.4 with respect to the NB-line o lower incisor eruption in females o tilted lower occlusal plane in males

. decreased facial convexity significantly in males

. more retrusive lips with respect to the E-line due to nose and chin growth

. nasolabial angle increased only in males even though overjet was significantly reduced in both genders

o the labiomental fold became more obtuse.

5.10. COMPARISON OF THE RESULTS FROM THE PRESENT STUDY WITH PUBLISHED UNTREATED SUBJECTS

This was a retrospective investigation and for ethical reasons it was not possible to compile a matching untreated Class II division 1 control group. Data collected some years ago may no longer be valid for today's population. Secular trends may occur in the craniofacial region as well as for weight, height and the onset of puberty (Tulloch et al., 1990). To enable some comparison to untreated subjects, data from the recent literature

were compiled Q.trelson et al., 1993; Lange et al., 1995; Illing et al., 1998; Morris et al., 1998). Care needs to be employed in determining conclusions from such an exercise. Error study results and methodology often differ between investigations" The Nelson et al. (1993) and Lange et al. (1995) data, were of a comparable treatment time to the three DISCUSSION t66

functional appliance groups in the current study. Reference planes in the Nelson et al. (1993) study differed to the present study, thus the results were not directly comparable. The Illing et at. (1998) and Morris et al. (1998) study was over a nine month period. All patients were of Caucasian origin, Class II division 1, aged 8 to 15 years old, had an ANB angle greater than six degrees and an overjet greater than seven millimetres. It was appreciated that this was a more severe Class II malocclusion when compared to the present study. Changes for cephalometric variables found in the current investigation were converted to a nine month period so that comparable analysis could be employed with this data. This was similar to the techniques of DeVincenzo (1991), Mills (1991), Windmiller (1993), Lund and Sandler (1998) and Keeling and co-workers (1998). This procedure has limitations, which must be respected, Individuals may be at different stages of their development. Some individuals may be just entering the spurt while others may be well advanced with respect to their growth spurt.

Morris and co-workers determined little change in the soft tissue profile over the nine month observation period of the controls. In addition, Talass, Talass and Baker (1987) reported that growth was associated with minimal changes in the soft tissue prof,rle in a period not exceeding 36 months. Without comparison to any controls it is difficult to determine the extent of the treatment effect.

The differences in facial growth in untreated Class II division 1 patients emphasise the importance of matching the numbers of each sex in our cephalometric studies in addition to age and similar malocclusions (Carter" 1987).

5.10.1 The llling, Morris and Lee Control Sample

The differences found between the controls and the treatment samples may represent population differences. An equivalent aged Class II division 1 Australian control population sample would have been ideal but all efforts in obtaining such data were unsuccessful. The remaining variables were determined to have no statistical differences present between the control sample and the three different appliance groups.

Post-treatment a number of statistically signif,rcant differences were detected which were not present pre-treatment. In the activator with combination headgear group, the males exhibited an overbite which was markedly reduced with treatment. It reduced DISCUSSIoN 167

1.4mm over a nine month period while in the control group it increased 0.3mm, The angle for the labiomental fold also increased 6.1'with treatment which was significant when compared to the 0.4o decrease in the controls. This represents the correction of the lip posture and function. Even though the ANB angle was considered significantly 'With different pre-treatment it was only in severity. treatment, the ANB angle decreased variable amounts in all groups while the controls increased 0.6'. The overjet follows a similar scenario having increased 0.8mm over a nine month period while it decreased markedly in all treatment groups. This makes the severity of the Class II situation worse if no treatment was undertaken. Tulloch and co-workers (1997b) found 30Yo of children, with an average age of 9.4 yearc, had a favourable response without any treatment,l5o/o had an unfavourable response with treatment, and 50% displayed no change. Obviously the patient's specif,rc position on the growth curve, during that time, is of importance.

The females in the activator with headgear group displayed slightly different trends with significant differences in the total face height, upper and lower lip thickness and distance from labrale superius to the E-line. Total face height increased significantly (2.lmm) more than the increase in the controls (0.7mm). Even with the application of headgear the total face height increased. This was due to the increase in the lower face height which was also markedly more than the controls. Minimal increase in the upper face height was detected in either of these two groups. Lip thickness increased slightly more in the treatment group. More retraction was evident in the upper lip than the lower lip with the activator. V/ith nose and chin growth, the upper lip retracted 0.1mm to the E-line in the controls and 1.4mm in the treatment group. There was a significant difference between the female activator group and the female controls which may be attributed to the uprighting of the upper incisors and the signif,rcant overjet decrease.

Post-treatment, the male Clark Twin Block sample displayed more statistically signif,rcant differences than any other treatment group. The ANB reduced 1o and the overjet 3.2mm. The overbite was also significantly reduced by 1.3mm. As expected lower face height increased significantly when compared to the slight decrease in the controls. This was most likely due to the mesial eruption of the lower molar to assist the Class II correction.

The upper lip to the E-line was again significantly retracted when compared to the controls. There was 1.3mm retraction in the Clark Twin Block group compared to DISCUSSION 168

0.3mm in the control sample. Again the 3.2mm overjet reduction in addition to the decrease in the ANB may have attributed to this finding.

Five variables associated with the sella vertical reference line increased significantly more in this male Twin Block group; B-Svert, PogSvert, LiSvert, SiSvert, STPSvert. These were all associated with the mandibular advancement effect of the Twin Block.

In both genders, facial convexity was significantly different between the controls and the Twin Block group prior to treatment but became similar with treatment. Even though with respect to facial convexity the controls became worse with time the positive effect of treatment deleted the statistical significance between the control and treatment groups. This was also detected in the male Fränkel sub-group.

The females in the Clark Twin Block sample also had a decrease of the ANB (1.3') which was significantly different from the 0.2o inqease in the ANB angle reported in the controls. Upper lip prominence was reduced 1.6mm with respect to the E-line in the treatment group whereas it only reduced 0.1mm in the controls. Upper lip length was seen to decrease in the controls 0.2mm probably with the increase in overjet, whereas it significantly increased 0.7mm in the Twin Block group. This increase probably represents the lengthening seen with retraction of the upper incisors and the overjet reduction. This is in contrast to Talass et al. (1987) who reported no change in the length of the upper lip with upper incisor retraction. The present study, however, is in agreement with Talass et al. (1987) with respect to the lower lip lengthening seen with treatment, especially with an increase in lower face height. The lower lip lengthening was in the order of 1.9mm in this study.

The males in the Fränkel group had an 8.5o more obtuse labiomental fold post-treatment whereas the controls only had a 0.5o increase in the angle. This was likely to be associated with the overjet correction and possibly the elimination of a lip trap.

B-point to sella vertical increased significantly (lmm) compared to the controls. In addition labrale inferius and sulcus inferius to sella vertical also increased significantly more with treatment.

The female Fränkel sub-group displayed a significant increase in total face height which appeared to be due to the increase in upper face height. There was also a significant increase in the soft tissue upper face height (1.3mm) compared to the (0.1mm) controls. DISCUSSIoN 169

Lower lip thickness, even though not marked, also displayed a significant difference to the controls post-treatment. This may be due to the uncurling of the lower lip and the adoption of a better lip posture post-treatment.

It appears as if the three different functional appliances have similar effects to varying degrees. Generally, similar variables become significantly different to the controls during the treatment period. This is in agreement with Johnston (1986) who believes all functional appliances work in a similar fashion.

5.10.2 The Lange, Kalra, Broadbent, Powers and Nelson Control Sample

It is interesting to observe this different population sample (Lange et al., 1995) with respect to changes which may occur. With genders combined the small decreases in SNA, which appeff not to be significantly different pre- and post-treatment, become statistically significant when compared to the controls. In the control group SNA actually increased 0.4o.

In the activator and the Clark Twin Block groups SNB was significantly larger than the controls. The Fränkel sub-division by sex for certain variables may be paramount in determining the changes that occur.

There was a significant decrease in the ANB angle with functional appliance treatment, It decreased the most in the Clark Twin Block (1.9') and the least in the Fränkel (1.2'). This was significant when compared to the 0.1o decrease detected in the controls which was due to differential mandibular growth.

True mandibular length and true ramus height were not analysed among the controls. Articulare was employed and with respect to its limitations, the activator appears to report the largest increase when compared to the controls.

The lower incisors appear to procline signif,rcantly more than the controls in only the Clark Twin Block treatment. The lower incisors of the controls actually uprighted slightly, while the activator with headgear uprighting was significantly more. The Fränkel is a tissue-borne appliance, thus proclination was limited compared to the tooth- borne appliances like the Clark Twin Block. The lack of incisor contact with the Fränkel DrscussroN t70

limited the proclination. V/ith protrusion of the mandible the Clark Twin Block exerts pressure onto the lingual surface of the lower incisors (Clark, l99l) and causes them to tip forward.

Lower face height and total face height increased the most in the Fränkel group, then the activator with headgear and least in the Clark Twin Block. However, the high-pull headgear would be expected to hold the vertical dimension and control the increase in face height the most. The Twin Block would be thought to play a role in the increase of the lower face height with the deliberate eruption of the lower molars into a Class I relationship. However, no significant increase was detected in the FMA in any of the treatment groups. The control group actually experienced a slight decrease in their FMA over this observation period.

In all treatment groups the nasolabial angle and the labiomental fold increased significantly. This is probably due to the similar reduction in overjet seen in each appliance. The overbite was also significantly reduced with the most overbite reduction being recorded in the Fränkel appliance. This corresponds with the biggest increase in the total face height being detected in the Fränkel appliance.

A statistical analysis determining differences in the changes in the landmarks between the controls and the treatment groups was undertaken. A significant difference was detected with the position of A-point in the x-axis when compared to the controls. It moved forward signihcantly less with functional appliance treatment. This has previously been reported by Harvold and Vargervik (1971), Pancherz (1979) and Windmiller (1993). The knowledge that A-point is not strictly a skeletal point but rather a deep dento-alveolar point may allow us to appreciate the remodeling of A-point which may occur with tooth movement (Mills, 1991). Thus with the retroclination of the upper incisors with functional appliance therapy, A-point may actually move distally along the x-axis due totally to dentoalveolar remodelling.

B-point also moved down the y-axis significantly more when compared to the controls. This is probably associated with the lower molar eruption and the increase in lower face height seen in all the functional appliance groups. DISCUSSIoN I7I

The upper incisor retroclined significantly in all groups and also significantly lengthened in the vertical in the Clark Twin Block and the Fränkel groups. The headgear in the activator group was efficient in preventing this migration in the y-axis.

The lower incisor edge moved significantly forward only in the Clark Twin Block group while in all groups significantly changing its position in the y-axis with the eruption of the lower molars and the increase in lower face height.

As expected with this change, pogonion also increased more in the y-axis than the controls.

With functional appliance treatment subnasale moved forward markedly less than in the controls. Again this is probably due to the maxillary restriction of the functional appliances and the associated effect on SNA.

Sulcus superius showed similar characteristics to subnasale in the x-axis but it also was signif,rcantly different to controls in the y-axis for the activator and the Fränkel groups. There was an increased amount of vertical movement in these two treatment groups.

In the x-axis for all appliances labrale superius was significantly reduced compared to controls. In agreement with Talass et al. (1987) the upper lip retraction was seen with the upper incisor retraction.

The activator and the Fränkel groups showed similar features with respect to the landmarks sulcus superius, labrale superius, sulcus inferius and soft tissue pogonion in the y-axis. Yet when compared to the controls they were significantly different. They all had markedly larger downward movements in the y-axis with treatment. This correlates well with the increase in face height. The Clark Twin Block also had movements in a similar downward direction but not to a statistically significant amount. This may be due to the shorter treatment time.

The activator with headgear group also displayed a smaller increase in the position of labrale inferius in the x-axis compared to controls. In the controls there was a 2.8mm increase in this lower lip point while the activator with combination headgear had only a 1.6mm increase. In agreement with the female subgroup of the Huggins and McBride (1915) study this was probably associated with the reduction in overjet and the relative posterior movement of the lower lip. This feature was not significant in the other two appliance groups. DISCUSSIoN t72

Sulcus inferius in the Twin Block sample was detected to move significantly more forward than the controls. This may have been partly due to the more pronounced proclination of the lower incisors in the Twin Block group.

5.'11 A COMPARISON OF THE ACTIVATOR WITH HEADGEAR, THE CLARK TWIN BLOCK, AND THE FRÄNKEL

Tulloch, Profht and Phillips (1997b) found 80% of patients had favourable results with functional appliances, and with headgear. There was no significant difference between the use of headgear or the functional appliances (Tulloch et al., 1997b). Interestingly, 30o/o of controls had a significantly favourable response. This response was not associated with severity of discrepancy, age, growth pattern or compliance. However, as expected great variations existed in response to growth modification and the response to functional appliances and headgear was not predictable (Tulloch et al, 1,997a). Headgear has been used more in the United States, and was thought to produce a pronounced effect on the maxilla, whereas functional appliances have been commonly used in Europe and thought to more affect the mandible (Tulloch et al., 1997a), either by increasing mandibular length or by relocating the mandible forward.

In the current investigation the pre-treatment age was similar between the groups. The numbers in each group, the sex distribution and the treatment time differed.

Sexual dimorphism was evident in all three functional appliance groups. Thus the data were originally analysed separately and later combined for specific variables where there was no gender difference detected. A summary of the specif,rc pre- and post- treatment differences between the genders can be found in the Appendix (8.5).

There is a need to consider age, sex and duration of treatment in the analysis of the results (Tulloch et al., 1990). In the current study the genders were analysed separately. Scattergrams were generated and correlation coefficients were calculated for each variable with respect to age and treatment time. This was to quantify strengths of association between the pairs of variables. Few biologically significant linear correlations were determined thus the two-way analysis of variance was performed without the inclusion of either treatment time or age as co-variates. The data was not statistically adjusted for age because chronological age was not a good indicator of developmental age. Moderate biological correlations were detected in some variables DISCUSSIoN 173

with treatment time. This was not unexpected due to the effect of growth. The data was adjusted for treatment time when comparison to the Illing et al. (1998) and Morris et al. (1998) controls was undertaken.

5.1L1 Two-way ANOVA

The three groups were comparable at the start of the study with respect to the ANB difference, skeletal malrelationships and overj ets.

Statistically significant sex differences existed for numerous linear measures, especially with respect to mandibular length, vertical face height and antero-posterior measures recorded from the sella vertical reference line. It is not unexpected to have males with larger dimensions of the face, especially if they are a little older than the females when treatment is initiated. Mandibular size in males was consistently larger in all three functional appliance groups, yet no other signihcant differences between the groups were evident. The males in all groups exhibited increased dimensions for soft tissue pogonion to soft tissue nasion in addition to subnasale, sulcus superius, labrale superius, and labrale inferius to the sella vertical reference line. This indicates the males may have possessed more protrusive lips pre-treatment.

The importance of keeping the data for the sexes separate must be stressed, otherwise significant hndings may be masked or exaggerated (Morris et a1., 1998).

P ost-Treatment Results

For conciseness the results for most of the post-treatment variables are better discussed as the differences between pre- and post-treatment comparisons.

Changes between pre- and post-treatment

In determining the changes between pre- and post-treatment the lower occlusal plane had the only significant difference associated with different applianee groups and sex. The lower occlusal plane was significantly different between the groups. The group differences existed between the activator and the Fränkel in males and between the activator and Clark Twin Block in females. Less significant gender differences were present. There was also a significant interaction demonstrated between the groups and sex for this variable. DISCUSSION t74

The remaining significant variables had no sex differences associated with them and in an attempt to increase the sample size the combined male and female data were employed to determine the differences between the groups. These included mainly variables associated with the lower incisors. The angular and linear measure of the lower incisor to the NB-line, the lower incisor to mandibular plane angle, the linear distance from the lower incisor apex to the mandibular plane and the interincisal angle. It has long been known of the problems orthodontists face in an attempt to prevent lower incisor proclination with functional appliance treatment. It appears as if most lower incisor proclination is in the Clark Twin Block, then the Fränkel and least in the activator with combination headgear.

5.11.2 One-Way ANOVA

No statistical signfficance with the one-way ANOVA

The two-way ANOVA determined significance, yet with some of these variables, there was no statistical significance shown between any two groups following analysis with the one-way ANOVA. These variables were LI-MP, LFH and Ls-A in the males and Ls-A in the females pre-treatment. Post-treatment LFH and Ls-A in the males demonstrated no significant association between any two groups. This lack of significance is probably demonstrated due to the decreased sample size and increased variability of the sample when sub-division is according to gender.

In assessing data for males and females separately, in cases where there was a significant difference between the genders and the appliance groups, the decrease of the sample size decreased the statistical power of the test. Thus no signihcant trend was detected in some situations. A large sample size is a major benef,rt in analysis of the results, so as to determine significant differences between the three functional appliance groups.

Pre-Treatmenl Results

Where the genders were combined pre-treatment, there were differences detected for the lower occlusal plane between the Fränkel and the activator and also the Clark Twin DrscussroN 175

Block. The Fränkel exhibited the lowest angle. In addition the Fränkel exhibited the lowest LI-MP distance and even though not significant with genders combined, may account for the decreased lower occlusal plane angle. This variable was significant in the females pre-treatment for the same appliance groups.

Pre-treatment, with genders combined, the lower lip thickness also showed up as significantly smaller in the Clark Twin Block when compared to both the activator and the Fränkel.

The females also demonstrated an increase in lower face height in the activator when compared to the Fränkel group. Interestingly the Clark Twin Block was not the group with the most decreased lower face height pre-treatment. Yet with the Clark Twin Block we often attempt to erupt the lower molars into a Class I relationship and subconsciously usually expect the largest increase in lower face height. Understandably, for vertical control mechanics, the patients with the greatest lower face height were selected for the activator with high-pull headgear.

P o st-Tr eatment Results

Many variables were noted to be significantly different between appliance groups post- treatment although there was no statistically signihcant sex effect was evident by the two-way ANOVA. V/ith genders combined, upper incisors \¡'lere more proclined and protrusive (U1-NA and U1-NA(mm)) in the Clark Twin Block group in comparison to the Fränkel group. Although not statistically significant, consideration of the means between these groups for UI-SN, confirms this observation.

The upper to lower face height ratio was significantly different post-treatment between the activator and Fränkel groups. Pre- and post-treatment, the activator had the smallest upper to lower face height ratio. This would be expected to be the case, instituting the need for high-pull headgear therapy. The activator with headgear group reduced this ratio slightly more than the Fränkel over the treatment period. It was reduced to some extent by all three appliance groups. DISCUSSIoN 176

The lower incisor to the NA line, however, displayed a significant difference between the activator and both the Clark Twin Block and the Fråinkel. Comparison of the means showed significantly less lower incisor proclination in the activator group.

This was confirmed with the lower incisor to mandibular plane angle, The activator- o. headgear combination actually retroclined the lower incisors 1.5

The interincisal angle was thus affected post-treatment, and significantly increased in the activator group when compared to the Clark Twin Block or the Fränkel, V/ith the activator having produced upper incisor uprighting and some lower incisor uprighting this is not an unexpected feature.

The lower occlusal plane was determined to be significantly reduced in the Fränkel. This was a feature that also existed pre-treatment and appears to be sample dependant.

Using the one-way ANOVA when genders were combined the ANB angle was significantly different post-treatment between the Clark Twin Block and the Fränkel. It was reduced to 4o (from an original 5.8") with the Clark Twin Block compared to 5.2" (from an original 6.3') with the Fränkel. This statistically signifrcant difference in the ANB angle did not exist pre-treatment. The groups were similar pre-treatment with respect to the ANB difference, skeletal malrelationships and the overjet. In agreement with DeVincenzo (1991) and Morris et al. (1998) it appeared as if the ANB was more markedly reduced with the Clark Twin Block than with other functional appliances.

Where groups and sex were significant in the two-way ANOVA the only variable significant post-treatment in the one-way ANOVA for males was the distance of the lower incisor apex to the mandibular plane. There was a significant increase of this linear measure in the activator group when compared to the other two groups. Thus even though the one-way ANOVA was unable to deteot a significant difference pre- treatment in the males for this variable, it did post-treatment. Thus in contrast to van Beek (1984) the activator allows lower incisor eruption to occur.

The females also exhibited this feature, however statistical significance was only present between the activator and the Clark Twin Block. This may be due to the females in the Fränkel group also having demonstrated some increased lower incisor eruption.

The females also displayed significant increases in lower face height and upper lip thickness in the activator group when compared with the other two groups. DISCUSSIoN 177

Changes between pre- and post-treatment

In the assessment of the differences between pre- and post-treatment, with genders combined, significant differences were detected between the activator and the other two functional appliances. These were significant for changes in the lower incisor to mandibular plane angle and lower incisor to the NA line (the linear and angular measurement). Signifrcance for the change in the interincisal angle was at the p<0.01 level. The activator minimised lower incisor protrusion and there was a non-significant 0.1o retroclination with respect to the NA line. Confirming the retroclination, the lower incisor to mandibular plane angle was also reduced by 1.5'. The other two functional appliances appear to be unable to stop the proclination and protrusion which, was especially evident with the Clark Twin Block. This proclination seen with the Clark Twin Block is in agreement with Clark (1988). Clark (1988), however, believes the lower incisors upright again during the support phase. The effect of the different functional appliances on the position of the lower incisors varied between groups.

With respect to the linear distance between the lower incisor apex and the mandibular plane significant differences were detected in the changes produced by the Clark Twin Block and the Fränkel. The Fränkel increased this measure by 1.lmm while the Clark Twin Block increased it only 0.1mm. The Clark Twin Block was also significantly different from the activator with respect to this variable. Possibly the effect of the full- time Clark Twin Block being retained by the clasps on the lower incisors stops their eruption. The Fränkel is a tissue borne appliance (McNamara and Brudon, 1993; Graber, I997a) and lower incisor eruption may more easily continue. This new lower incisor position may be expected to have an effect on the lower lip position. In actual fact the change of the lower lip to E-line was reduced 0.2mm in the Clark Twin Block and 1.3 mm in the Fränkel. The final position of the lip to the E-line was compffable in both groups, and within acceptable limits. Thus the change performed by the Fränkel was more remarkable, but the final result was similar.

The lower occlusal plane was determined to be significantly different between the activator and the Fränkel for the males. The Fränkel decreased the lower occlusal plane 1.9" more than the activator. The prevention of molar eruption and increased lower incisor eruption in the activator group may play a role in limiting the decrease of the lower occlusal plane. The females however differed between the activator and the Clark Twin Block with respect to the lower occlusal plane. In the females, the Clark Twin Block decreased the occlusal plane relative to the mandibular plane 2.9" more than in DIScUSSIoN 178

the activator group. This was an expected finding with the guided lower molar eruption seen with the Clark Twin Block technique.

5.12 COMPARISON OF SKELETAL AND DENTAL CHANGES CONTRIBUTING TO OVERJET AND MOLAR CORRECTION

Overjet reduction appears to be the identifying factor which determined successful treatment. Molar correction usually occurs simultaneously.

This section presents a summary of the skeletal and dental changes for each appliance, as determined from a modified version of the analysis described by Pancherz and Hansen (1986), and Pancherz (1997). This modified version uses SN-7o rather than the sella nasion line which was originally used by Pancherz and Hansen (1986) and it omits the occlusal line. It separates the horizontal and the vertical components of the skeletal and dental changes seen in overjet and molar correction. The original overjet and overbite were calculated from the "x" and "y" coordinates thus the amount of overjet reduction can be related back to the Cartesian axes. Within each functional appliance group males and females have been combined for this analysis.

Figure 25 Gomparison of skeletal and dental horizontal changes contributing to overjet correction.

Overjet Correction

ACT: 4.23 mm

GTB: 5,16 mm

FR: 4.5 mm

Skeletal De¡rtal

ACT: 1.25 mm (2s.5%) ACT: 2.98 mm (70.5o/o)

CTB: 1.97 mm (38%) CTB: 3.19 mm (62%)

FR: 0.82 mm (18o/o) FR: 368mm (82%)

Maxilla Mandible Maxilla ble

ACT: -0.28 mm ACT: 1.53 mm ACT: 2.82mm ACT: 0.16 mm

CTB: -0.42 mm CTB: 2.39 mm CTB: 1.96 mm CTB: 1.23 mm

FR : -0.64 mm FR: 1.46 mm FR: 2.48 mm FR : 1.2 mm Minus sign ("-") denotes unfavourable changes in correction. DrscussroN t79

This summary was determined using the x and y coordinates of the SN-7' Cartesian system. The changes in the x-axis are provided in tabular form. The changes in the y- axis must also be considered. This is a simplistic view of the actual changes which, occur. The matrix and intramatrix rotations which occur with growth must be recognised and their effect appreciated in analysis of this data (Björk, 1963; Björk and Skieller, 1983).

In the activator I headgear combination, the upper incisal edge moved occlusally along the y-axis 2.53mm, while the lower incisor edge moved vertically downwards 4.45mm. The downward movement of the maxilla, measured at A-point was 2.32mm. thus the actual dental component of vertical migration of the upper incisor was 0.21mm. The incisors were held by the high-pull headgear. In the mandible, pogonion moved down the y-axis 6.l2mm, thus the dental movement of the lower incisor edge involved l.67mm of eruption.

The Clark Twin Block group displayed not only antero-posterior movement of the incisors but also a vertical component. The upper incisor moved down the y-axis 2.68mm and the lower incisor edge moved down 4.83mm. Once the skeletal movement was subtracted from this, the vertical dental movement of the upper incisor was 1.03mm occlusally. The lower incisor edge appears to move 0.18mm downward, which would imply either proclination, intrusion or incisal wear have occured. In association with the other evidence provided proclination is the most realistic option.

The Fränkel appears to move the upper incisal edge 0.3lmm occlusally, while the lower incisal edge appears to move only 0.01mm occlusally. DISCUSSION 180

Figure 26 Gomparison of skeletal and dental horizontal changes contributing to molar correction.

Molar Correction

ACT: 3.41 mm

CTB: 4.37 mm

FR: 2.85 mm

Skeletal Dental

ACT: 1.25 mm (36%) ACT: 2.16 mm (64%)

CTB: 1.97 mm (45%) CTB: 24 mm (55%)

FR: 0.82 mm (2e%) FR: 2.03 mm (7 1o/o)

Maxilla Mandible Maxilla Mandible

ACT: -0.28 mm ACT: 1.53 mm ACT: 1.38 mm ACT: 0.78 mm

CTB: -0.42 mm CTB: 2.39 mm CTB: 0.87 mm CTB: 1.53 mm

FR : -0.64 mm FR: 1.46 mm FR: 0.2'1 mm FR: 1.82 mm Minus sign ("-") denotes unfavourable changes in correction

Thus a larger dental component is present for the Class II conection of the incisors. This is due to the uprighting of the upper incisors and often associated proclination of the lower incisors. In addition, the analysis of molar correction must be analysed with the error study results in mind. The reliability of upper molar identification, in the present study was not as precise as other landmarks

In the activator I headgear group it appears that in addition to the antero-posterior movement, the upper molar continued to move occlusally 2.37mm. The lower molar moved down 3.85mm. A-point moved down vertically 2.32mm, thus excluding the skeletal component, the upper molff only moved occlusally 0.05mm. It was obviously held by the high-pull headgear. This degree of measurement accuracy, however, is outside the measurement error capabilities in the identification of this landmark. DISCUSSIoN 181

Precision to two decimal places is not possible here but it has been used to better demonstrate the magnitude of the dental movement.

In a similar fashion using pogonion as the skeletal reference, it was noted that the lower molar actually moved occlusally 227mm. Eruption of the lower molar assisted the Class II correction.

In the Clark Twin Block group the upper molar dental component appeared to have moved vertically downwards 0.16mm. The lower molar was erupted l.28mm and moved mesially in an attempt to correct the Class II molar relationship.

There was 0.33mm dental eruption of the upper molar in the Fränkel group. The amount of lower molar eruption was markedly more in the assistance of the Class II correction of the molar relationship. It was in the vicinity of 1.49mm. In agreement with Tulloch et aI. (7997b,1998) a wide variation in response was detected. CoNcr.usroNS 182

6. CONCLUSIONS

The clinical relevance of the data must be interpreted with caution. In general, mean changes in the soft tissues are small although there is large variability in individual values. We must remember that a statistically significant result does not necessarily mean there is clinical relevance (Battagel, 1993). The assumptions are often made that the soft tissue profile is closely related to its underlying hard tissues, and that changes in the skeletal profile provide predictable soft tissue changes.

The basic conclusions determined from this study were:

1. All the appliances produced a measurable change in the skeletal, dentoalveolar and soft tissues.

2. The ANB angle decreased in all groups, especially the Clark Twin Block.

3. The SNA angle decreased in the Clark Twin Block group and did not change in the activator with headgear combination or the Frankel groups. This may indicate maxillary restriction assisting the Class II correction.

4. All groups displayed forward movement of pogonion with anterior movement of the mandible being greatest in the Clark Twin Block.

5. All appliances displayed an increase in face height.

6. No significant change in the FMA was detected in any of the appliances. CoNcI-usIoNS 183

7. All appliances were efficient in overjet and overbite reduction

8. The Fränkel displayed the greatest upper incisor retroclination while the Clark Twin Block displayed the greatest lower incisor proclination.

9. The null hypothesis that the soft tissue profile change is independent of the type of functional appliance used in correction of the Class II division 1 patient was rejected. Table 4l summarises the significant differences between the three functional appliances.

10. Sexual dimorphism was evident for certain craniofacial and soft tissue variables. The variables are presented in the Appendix (8.5).

11. In agreement with Mills (1991) and Tulloch et al. (I997b, 1998) a wide variation in response was detected. This is displayed for selected variables in the Appendix (8.7).

12.The effect of facial strain and lip tension needs to be considered when assessing the soft tissues. With retraction of the upper incisors the upper lip is seen to thicken slightly (Wisth, 1974). This study did not completely support this view. It is in agreement with the Clark Twin Block group but not with the activator or Fränkel.

13. Vertical growth and manipulation of the occlusal plane assists in Class II correction.

14. Possibly the remodelling of the glenoid fossa may "create the appearance" of an increased mandibular length by anterior positioning and forward translation of the mandible. The degree of glenoid fossa remodeling was not analysed in the current investigation. However it also needs to be appreciated when assessing the effect of functional appliances.

15. In agreement with Dermaut and Aelbers (1996) long-term evaluation is necessary to determine stability of the treatment effect. It was not possible for the current study, but is recommended for future research. CoNcrusIoNS 184

The summary table highlights signihcant differences between the three functional appliance groups.

Table 4l Summary of statistically significant differences between the three functional appliance groups

Highlighted groups are significantly different from each other (with genders combined):

Differences between pre- and post-treatment SUMMARY ACTIVATOR CTB FRÄNKEL

SNA No change Decrease (females) No change

SNB lncreased lncrease (esp. males) lncrease (in males)

ANB Decreased

Mandibular length lncreased lncreased lncreased

(esp. in females) (esp. in males)

Palatal plane Tipped anteriorly No change Tipped (in females)

FMA No change No change No change

Upper lncisors Uprighted

Lower lncisors No change Protruded

Proclined

L1 to MP distance Some Eruption No eruption

LOP Decreased less than Decreased in females Decreased more in CTB or FR males

Facial convexity No change Decreased Decreased in males

Face height lncreased

Upper lip More retraction of Retraction Retraction upper lip compared to Lower lip lower lip -with respect to E-line -with respect to E-line

Upper lip thickness Thickest in female 2nd Thickest in female Thinnest upper lip

Lower lip to E-line Retraction (in males) No change Retraction

Nasolabial angle No change lncreased in males lncreased in males

Labiomentalfold More obtuse More obtuse More obtuse CoNcLUSIoNS 185

6.1 FUTURE RESEARCH

Even after many years of research, many limitations exist in our knowledge of functional appliances and we face a vast challenge in overcoming these limitations to determine what actually occurs.

Future research is important to accurately determine what actually does occur with different functional appliances. In addition to the current criteria, larger sample sizes (Morris et al., 1993) and the selection of patients according to face height, would be of beneht (Illing et a1.,1998). It would be interesting to examine the results in the long- term. At present it is difficult to determine if the treatment results remain or if they evaporate and future growth will return these cases to the same pattern as that of nntreated cases (Jakobsson, 1967, DeYincenzo, 1991). The possibility of drawing conclusions about stability entices every researcher. To recall the same patients after five, ten and twenty years would be ideal. In addition to the cephalometric analysis, a study model analysis of the same patients and a comparison to the cephalometric data would be informative.

Courtney et al. (1996) noted large cranial base changes which produced small statistically significantly changes at basion. An analysis of the present data with a different superimposition technique, for instance, using Basion horizontal (Coben, 1979) may provide an interesting and different interpretation of ihe data. This research is to be initiated in the immediate future.

Further research is obviously also necessary to help resolve the question concerning the desirability of a single large mandibular advancement or a series of progressive increments. Petrovic (1994) noted a very small intensihcation in the contractile activity of the lateral pterygoid with Class II elastic wear, allowing supplementary growth of the condylar cartilage. Class II elastics mainly stimulate the retrodiscal pad activity (Petrovic and Stutzmann, 1997). It would be interesting to determine if Class II elastics provide a similar or even better functional appliance effect (Gianelly et al., 1984). Few studies have considered the growth modification effect of conventional fixed appliances (Tulloch et al., 1990). Cephalograms and laser scanning had been used by Moss et al. (1993) and the rate of overjet reduction observed in the evaluation of magnetic twin block efficiency. They produced twice the amount of change in the soft tissues (Moss et al., 1993). Future research could include a comparative analysis with Class II elastics and/or magnets incorporated into certain functional appliances. CoNcl-usroNS 186

Standardisation of the recording of the soft tissues, especially lip posture is important. The construction of a well organised and executed prospective study with control of the variables already discussed would be the ideal in determining the effects of these functional appliances on the hard and soft tissues.

However conventional radiographic identification is often inaccurate in differentiation of all but the grossest changes (Baumrind andFruntz, l97lb.). The bony changes we want to detect are usually subtle (Gerber, 1990). Future studies with magnetic resonance imaging (Petrovic and Stutzmann, 1997; Ruf and Pancherz, 1998) and laser scanning (Moris et al., 1998) may provide greater insight into the actual changes that occur.

Johnston (1963) stated that our patients definitely looked better post-treatment, but scientific proof of the changes involved was lacking. Sadly, over thirty years later this statement still holds true. ReF.BRBNCeS r87

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Voudouris J.C. (1988). Glenoid fossa and condylar remodeling following progressive rnandibular protrusion in the juvenile Macaca fascicularis. Master's Thesis, University of Toronto. Cited in Woodside D.G. (1997). Studies of Functional Appliance Therapy. In T.M. Graber, T. Rakosi, & A.G. Petrovic, Dentofacial Orthopedics with Functional Appliances. (pp. 74-82). St. Louis, Missouri. Mosby - Year Book, Inc.

Webster T, Harkness M, & Herbison P. (1996). Associations between changes in selected facial dimensions and the outcome of orthodontic treatment. Am J Orthod Dentofocial Orthop, 110:46-53.

Wieslander L. (1984). Intensive treatment of severe Class II malocclusions with a headgear-Herbst appliance in the early mixed dentition. Am J Orthod, 86, I-13.

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Whetten L.L, &, Johnston L.E.Jr. (1985). The control of condylar growth: an experimental evaluation of the role of the lateral pterygoid muscle. Am J Orthod, 88.' 1 I 1 - 1 90.

Williams S, & Melsen B. (1982). Condylar development and rnandibular rotation and displacement during activator treatment. An implant study. Am J Orthod, B1:322-326.

Windrniller E.C. (1993). The acrylic-splint Herbst appliance: A cephlometric evaluation. Am J

Orthod Dentofocial Orthop, I 04 :1 3 -84.

Wistlr J. (1974). Soft tissue response to upper incisor retraction in boys. Br J Orthod, 1:199-204. REFERENCES 2tl

Woodside D.G. (1973). Some effects of activator treatment on the mandible and midface. Trans Euro Orthod,Soc, pp 443. Cited in Rakosi T. (1997). The Activator. In T.M. Graber, T. Rakosi, & A.G. Petrovic, Dentofocial Orthopedics with Functional Appliances, (pp. 161-187). St. Louis, Missouri. Mosby - Year Book Inc.

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8 APPENDICES

8.1 Landmarks

8.1.1 HARD TISSUE POINTS.

Most points have been located in the mid-sagittal plane so as to ensure constant magnification. Wherever it was necessary to select bilateral landmarks which, were not in the midsagittal plane, where the two images were visible an average between the right and left sided structures was employed.

1. Sella (S) The geometric centre of sella turcica, the pituitary fossa of the sphenoid bone, as determined by visual inspection.

2. Nasion (N) The most anterior point visible of the frontonasal suture in the midsaggital plane. If at any time this was not apparent, the deepest point on the profile between the frontal and nasal bones was taken to be nasion.

3. Orbitale (Or) The most inferior point on the infraorbital margin.

4. Porion (Po) The most superior point on the bony external auditory meatus, located posteriorly to the mandibular condyle.

5. A-point (A) The most posterior midline point on the profile of the maxilla between the anterior nasal spine and AppnNnlcBs 213

the junction of the upper incisor and labial alveolar process (prosthion).

6. B-point (B) The most posterior midline point in the concavity of the mandible between the chin point and the alveolar crest.

7. Anterior Nasal Spine The tip of the anterior nasal spine.

(ANS)

8. Posterior Nasal Spine The tip of the posterior nasal spine.

(PNS)

9. Upper Incisal Edge The crown tip of the most prominent upper

(u1E) lnclsor.

10. Upper Incisor Apex The root apex of the most prominent upper

(u1A) lnclsor

11. Upper Molar Distal The most posterior-inferior point on the distal

Cusp Reference Point border of the average of the upper first permanent

(UM) molar crowns.

12. Lower Incisal Edge The crown tip of the most prominent lower incisor (L1E)

13. Lower Incisor Apex The root apex of the most prominent lower

(L1A) incisor. AppeNntcBs 214

14. Lower Molar Distal The most posterior-inferior point on the distal

Cusp Reference Point border of the aveÍage of the lower first permanent

(LM) molar crowns.

15. Pogonion (Pog) The most anterior point of the external outline of the mandibular symphysis.

16. Gnathion (Gn) The most anterior-inferior point of the external outline of the mandibular symphysis.

17. Menton (Me) The most inferior point of the external outline of the mandibular symphysis.

18. Gonion (Go) The midpoint of the curvature of the angle of the mandible. Located by bisecting the angle formed by the mandibular plane and a plane through the posterior border of the ramus and the inferior border of the mandible.

19. Articulare (Ar) The point of intersection of the dorsal contour of the mandibular condyle and the temporal bone.

20. Condylion (Co) The most posterior-superior point on the curvature of the average of the two condyles. Located point of tangency to a perpendicular construction line to the anterior and posterior borders of the condylar head.

21. Pterygomaxillary The most posterior-superior point on the average

Fissure (PTM) of the outlines of the pterygmaxillary fissures. AppBNrrcBs 215

22. Basion (Ba) The most inferior-posterior point on the anterior margin of foramen magnum. It is part of the basilar portion of the occipital bone.

8.1.2 SOFT TISSUE POINTS.

23. Soft Tissue Nasion(STN)The most concave point in the midline, between the forehead and the nose.

24. Nasal Tip (N tip) The most anterior soft tissue point of the nose, in the midline.

25. Subnasale (Sn) The midline soft tissue point where the upper lip meets the lower border of the columella.

26. Sulcus Superius (Ss) The most posterior, concave soft tissue point of the upper lip located between subnasale and labrale superius.

27"Labrùe Superius (Ls) The most prominent midline point on the soft tissue outline of the upper lip.

28. Upper Lip Lowest PointThe most inferior point of the upper lip (uLL)

29.Lower Lip Highest Point The most superior point of the lower lip. (LLH) AppnNrrcns 216

30. Labrale Inferius (Li) The most prominent midline point on the soft tissue outline of the lower lip.

31. Sulcus Inferius (Si) The most posterior, concave soft tissue point of the lower lip located between the lower lip and the chin.

32. Soft Tissue Pogonion The most anterior and prominent point soft tissue

(ST Pog) midline point on the chin.

33. Soft Tissue Menton The point where a vertical line from menton

(ST Me) bisects the soft tissue outline of the chin.

8.2 CALCULATION OF ANGULAR AND LINEAR VARIABLES.

13 angular and 19 linear hard tissue variables were selected, while the soft tissue variables consisted of 4 angular and 17 linear measurements.

8.2.] HARD TISSUE VARIABLES

1. Sella-Nasion to Frankfort Horizontal (SN-FH)

The angle formed between sella-nasion and Frankfort horizontal

2. SNA angle (SNA)

Represents the degree of prognathism of the maxilla.

The angle between sella-nasion and nasion-A point.

3" Maxillary plane to sella-nasion (MaxPl-SN)

The angle formed between sella-nasion and anterior nasal spine - posterior nasal spine. AppBNrrcBs 217

4. Maxillary Length (Co- A point)

The linear distance from condylion to A point.

5. Upper Incisor to Sella-Nasion (Ul-SN)

The angle between the sella-nasion line and the long axis of the upper central incisor.

6. Upper Incisor to NA angle (UI-NA fl) The angular measurement, between the long axis of the upper incisor and the line drawn through nasion and Downs' A point.

7. Upper Incisor to NA distance (UI-NA [mml)

The linear distance, in millimetres, from the upper incisal cÍown tip to the line drawn through nasion and Downs' A point.

8. Upper Incisor to Maxillary plane angle (Ul-MaxPl [o])

The angle between the long axis of the upper central incisor and the line drawn through the anterior nasal spine and posterior nasal spine.

9. Interincisal angle (U1-L1 ['l) The angle between the long axes of the upper and lower central incisors.

10" Lower occlusal plane

The line drawn through the landmarks lower incisor edge (LlE) and lower molar distal cusp reference point (LM). APPENDICES 218

11. ANB angle (ANB ['l) Represents the antero-posterior apical base relationship of the maxilla to the mandible. Measured as the angular difference between the SNA and SNB angles, where SNB is the angle formed between the sella-nasion line, and the line drawn through nasion and Down's B-point.

12. Lower Incisor to NB angle (LI-NB ['l) The angular measurement, between the long axis of the lower incisor and the line drawn through nasion and B point'

13. Lower Incisor to NB distance (UI-NB [mml)

The linear distance, in millimetres, from the lower incisal crown tip to the line drawn through nasion and B point.

14. Lower Incisor to Mandibular plane angle (IMPA ['l)

The angle between the mandibular plane and the long axis of the lower incisor.

15. Lower Incisor to Mandibular plane distance (LI-MP [mml)

The linear distance between the mandibular plane and the apex of the lower incisor.

16. SNB angle (SNB ["])

Represents the degree of prognathism of the mandibular apical base. It is the angle between sella-nasion and a line through nasion and Down's B point.

17" True mandibular length (Co-Gn [mm])

The linear dimension between condylion and gnathion' APPENDICES 2t9

18. Mandibular length (Ar-Gn [mm])

The linear dimension between articulare and gnathion

L9. True ramus height (Co- Go [mm])

The linear distance between the points of condylion and gonion.

20. Ramus height (Ar-Go [mm])

The linear distance between the points of articulare and gonion.

21. Upper anterior face height (UFH [mml)

Measured from nasion to the anterior nasal spine.

22.Lower anterior face height (LFH [mm])

Measured from the anterior nasal spine to menton.

23. Anterior face height ratio (UFH:LFH)

The proportion of the anterior upper face height as compared to the anterior lower face height, expressed as a ratio.

24.Totalanterior face height (Na-Me [mmì)

Measured from the nasion to menton.

25. Posterior face height (S-Go [mm])

The linear distance between sella and gonion.

26 Posterior to anterior face height ratio (PFH:AFH)

The proportion of the posterior face height to the anterior face height, expressed as a ratio. AppsNrIcBs 220

27. Frankfort Horizontal to Mandibular plane angle (FMA ['ì) The angle between the mandibular plane and the line though orbitale and porion.

28. A-point to Sella vertical [mml The horizontal distance between the Sella vertical line and A- Point.

29. B-point to Sella vertical [mm] The horizontal distance between the Sella vertical line and B- Point.

30. Pogonion to Sella vertical [mml The horizontal distance between the Sella vertical line and pogonion.

3l.Overjet (OJ [mm]) The incisor overjet, measured from the upper incisor edge to the lower incisor edge along the x-axis.

32.Overbite (OB [mm]) The degree of vertical overlap of the upper central incisor edge, over the lower incisor edge along the y-axis.

8.2.2 SOFT TISSUE VARIABLES.,

33. Facial convexity (F. conv" [']) The angle measured between soft tissue nasion - nasal tip-soft tissue pogonion. AppBNnIcns 221

34. Nasolabial angle (N-L ang. [']) The angle measured between the nasal tip-subnasale-labrale superius.

35. Labiomental fold (L-M fotd ['l)

The angle measured between labrale inferius-sulcus inferius- soft tissue pogonion.

36. Modified harmony angle ('H' angle ['])

The angle measured between soft tissue nasion-labrale superius- soft tissue pogonion.

37. Upper lip thickness [mm]

The linear distance between A point and labrale superius'

38. Lower lip thickness [mm]

The linear distance between B point and labrale inferius

39. Soft tissue total face height (ST TFH [mm]) The linear distance between soft tissue nasion and soft tissue menton.

40. Soft tissue upper face height (ST UFH [mml)

The linear distance between soft tissue nasion and subnasale.

41. Soft tissue lower face height (ST LFH [mm])

The linear distance between subnasale and soft tissue menton. AppBNorcss 222

42. Soft tissue lower face percentage (ST LFH%)

The linear distance between subnasale and soft tissue menton, compared to the linear distance between soft tissue nasion to soft tissue menton.

43. Upper lip to E line lmml The linear distance from the E line (nasal tip to soft tissue pogonion) to labrale superius.

44"Lower lip to E line lmml The shortest linear distance from the E line (nasal tip to soft tissue pogonion) to labrale inferius.

45. Upper lip length (ULL [mmì)

The shortest linear distance from subnasale to the most inferior point of the upper lip.

46. Lower lip length (LLL [mml) The linear distance from soft tissue menton to the most superior point of the lower lip.

47. Soft Tissue Pogonion to Soft Tissue Nasion lmml

The linear distance between these two points

48. Subnasale to Sella vertical [mm] The horizontal distance between the Sella vertical line and subnasale.

49" Sulcus Superius to Sella vertical [mm]

The horizontal distance between the Sella vertical line and sulcus superius. APPENDICES 223

50. Labrale Superius to Sella vertical [mm]

The horizontal distance between the Sella vertical line and labrale suPerius.

51. Labrale Inferius to Sella vertical [mm]

The horizontal distance between the Sella vertical line and labrale inferius.

52. Sulcus Inferius to Sella vertical [mml

The horizontal distance between the Sella vertical line and sulcus inferius.

53. Soft tissue Pogonion to Sella vertical lmml

The horizontal distance between the Sella vertical line and soft tissue Pogonion. AppeNnrcBs 224

8.3 Gorrelations and coefficients of determination

Table 42 : Significant correlations between age and pre-treatment craniofacial / soft tissue variables.

The activator with combination headgear:

AGE MALES FEMALES

ACT. r 12 r prob f 12 r prob.

Co-A 0.53 0.28 0.03 * o.54 0.29 o.02 "

U1-SN -0.51 0.26 0.03 *

U1-L,I 0.48 0.23 0.05 *

L1-NB 0.53 0.28 0.03 *

L1-NB(mm) 0.51 0.26 0.04 *

IMPA o.52 0.27 0.03 *

L1-MP 0.48 0.23 0.04 *

Co-Gn 0.53 0.28 0.03 * 0.52 0.27 0.03 *

Ar-Gn 0.51 0.26 0.04 * 0.50 0.25 0.03 *

Co-Go 0.48 o.23 0.04 *

Ar-Go 0.48 0.23 0.04 *

S-Go o.52 o.28 0.03 "

OB 0.56 0.31 o.o2 *

Ls-A 0.51 0.26 0.04 "

ST TFH 0.56 0.32 0.02 *

ST UFH 0.53 o.28 0.03 * o.52 0.27 0.03 *

Sn-Svert 0.59 0.35 0.01 * Appsxorces 225

The Clark Twin Block:

MALES FEMALES

I ¡2 r prob. f 12 r prob.

MaxPl-SN -0.50 o.25 0.04 * * SNB 0.59 0.34 0.01 ** Co-Gn 0.62 0.38 0.01

Ar-Gn 0.62 0.38 0.01 **

Co-Go 0.55 0.31 0.02 *

Ar-Go 0.55 0.30 0.02 *

UFH 0.68 0.46 0.01 " * S-Go 0.58 0.34 0.01 * PFHAFH 0.54 o.29 0.03

B-Svert 0.63 0.39 0.01 ** ** PogSve 0.64 0.41 0.01

Ls-A 0.63 0.40 0.01 ** * ST TFH 0.61 0.38 0.03

Sn-Svert 0.63 0.40 0.01 *"

SsSvert 0.61 0.38 0.01 '*

LsSvert 0.55 0.30 0.02 *

LiSvert 0.65 0.42 0.01 *"

SiSvert 0.65 o.42 0.01 **

STPSvert 0.66 o.44 0.00 **

The Fränkel appliance:

MALES FEMALES

r 12 r prob. r 12 r prob. * Ar-Gn 0.53 0.28 0.04 ** UFH 0.70 0.49 0.01 *" UFHLFH 0.70 0.50 0.01

PogSve o.52 o.27 0.05 "

ST LFH -0.58 0.34 0.02 *

STLFH% -0.61 0.38 0.02 " AppeNnrcss 226

Table 43 : Significant correlations between treatment time and treatment change in craniofacial / soft tissue variables.

The activator with combination headgear:

Tx. Time MALES FEMALES

ACT. r 12 r prob. r 12 r prob. *** Co-A -0.86 0.75 0.00

U1-NA(mm) -0.61 0.38 0.01 "* ** L1-NB 0.70 0.49 0.00 * L1-NB(mm) 0.47 o.23 0.05

IMPA 0.58 0.34 0.01 " ** L1-MP -0.71 0.50 0.00 * SNB -0.56 0.31 0.02 *** Co-Gn -0.92 0.85 0.00 -0.67 0.45 0.00 "* *** ** Ar-Gn -0.90 0.81 0.00 -o.71 0.51 0.00 *** ** Co-Go -0.80 0.63 0.00 -0.63 0.40 0.01 ** Ar-Go -0.79 0.62 0.00 *** -0.61 0.37 0.01 * UFH -0.58 0.33 0.02 ** ** LFH -0.70 0.48 0.00 -o.62 0.38 0.01 *** *** N-Me -o.82 0.68 0.00 -0.84 0.70 0.00 *** *** S-Go -0.90 0.80 0.00 -0.85 0.73 0.00 **" PFHAFH -o.82 0.68 0.00 * FMA 050 o.25 0.04

A-Sved -0.69 0.47 0.00 **

0* OJ -0.60 0.36 0.01 * F.conv 0.60 0.36 0.01

Ls-A -o.57 0.33 0.02 *

ST TFH -0.79 0.62 0.00 "** * ST UFH -0.47 0.22 0.06 ** ST LFH -o.74 0.55 0.00 -0.56 o.32 0.01 " * L¡-E 0.57 0.33 0.01

STP-STN -0.65 o.42 0.01 "o

Sn-Svert -0.90 0.80 0.00 *** AppBNnrcns 227

The activator with combination headgear (continued)

Tx. Time MALES FEMALES

ACT. r 12 r prob r 12 r prob.

SsSvert -0.76 0.57 0.00 *** ** LsSvert -0.64 o.41 0.01

LiSvert -0.57 o.32 0.02 *

SiSvert -0.59 0.35 0.01 *

STPSvert -0.57 0.32 0.02 *

The Clark Twin Block:

Tx. Time MALES FEMALES

CTB f 12 r prob. r 12 r prob. * Co-A -0.50 0.25 0.08

Ar-Gn -0.53 0.28 0.03 * * Co-Go -0.68 0.46 0.01 * N-Me -0.54 0.30 o.o2

S-Go -0.53 0.28 0.03 " -0.58 0.33 0.04 "

A-Svert -0.50 0.25 0.04 *

L-Mfold 0.50 o.25 0.04 * * Hangle -0.62 0.38 0.02 ** Ls-A 0.72 0.51 0.01

ST TFH -0.53 0.28 0.03 *

ST UFH -0.60 0.36 0.01 "

LLL -0.58 0.34 0.01 *

STPSvert -0.52 o.27 0.03 * AppnNntcBs 228

The Fränkel appliance

Tx. Time MALES FEMALES

FRÄNKEL r 12 r prob. r 12 r prob.

Co-A -0.55 0.30 0.04 "

L1-NB(mm) 0.53 o.28 0.05 *

L1-MP -0.55 0.30 0.04 *

SNB -0.54 o.29 0.05 "

Co-Gn -0.57 0.33 0.03 * -0.60 0.36 o.o2 *

Ar-Gn -0.61 o.37 0.02 * -0.63 0.40 0.02 *

Co-Go -0.61 0.37 0.02 "

Ar-Go -0.69 0.47 0.01 **

UFH -0.56 o.32 0.03 * -0.63 0.40 o.o2"

N-Me -0.56 0.31 0.03 * -0.61 0.38 0.o2* * S-Go -0.57 0.33 0.03 -0.78 0.61 0.00 *"

PFHAFH -0.67 0.45 0.01 **

B-Svert -0.52 0.27 0.05 *

F.conv 0.56 0.32 0.04 "

Hangle -0.63 0.39 0.02 *

ST TFH -0.61 0.38 o.o2*

ST UFH -0.60 0.36 0.02 *

Ls-E 0.67 0.45 0.01 **

Li-E 0.56 0.32 0.04 *

LLL -0.75 0.56 0.00 **

STP-STN -0.55 0.30 0.04 "

Sn-Svert -o.52 0.27 0.05 *

LiSvert -0.70 0.48 0.00 *"

SiSvert -0.61 0.37 0.02 *

STPSvert -0.63 0.39 0.01 * ApprNorcps 229

8.4 Cranial base superimposition- treatment changes for landmarks using SN-7' Gartesian axes

Table 44 Cranial Base Superimposition- treatment changes for activator / headgear hard tissue landmarks.

ACT Total Males Females

landmark MEAN SD MEAN SD MEAN SD

S X -o.02 0.77 -0.15 0.75 0.10 0.80

v -0.09 1.47 -0.20 1.78 0.01 1.13

N X 0.87 1.39 0.93 1.78 0.82 0.95

v -0.45 1.61 -0.38 1.60 -0.50 1.67

Or x 0.50 1.63 0.55 1.79 0.45 1.52

v -0.67 1.37 -0.87 1.59 -0.48 1.14

Po X -0.37 1.45 -0.53 1.73 -o.22 1.16

v -0.01 1.64 -0.11 1.57 0.08 1.74

A X 0.28 1.30 0.62 1.35 -0.05 1.21

v -2.32 2.85 -2.72 2.51 -1.94 3.17

B X 1.72 1.73 1.64 '1.56 1.79 1.91

v -4.82 3.42 -5.29 3.46 -4.38 3.42

ANS X 0.21 1.99 0.40 2.18 0.03 1.83

v -2.10 2.57 -2.67 2.19 -1.56 2.85

PNS X -0.33 1.90 0.00 2.14 -0.64 1.64

v -1.11 1.95 -1.36 2.13 -0.87 1.80

U,IE X -2.54 2.07 -1.95 1.98 -3.10 2.05

v -2.53 2.65 -2.47 2.95 -2.60 2.41

U1A X 0.64 1.85 0.75 1.99 0.54 1.75

v -1.41 2.95 -1.53 3.15 -1.30 2.83

UM X -1.1 0 1.87 -1 .10 1.46 -1.1 0 2.24

v -2.37 3.21 -2.58 3.36 -2.17 3.14

L1E X 1.69 1.74 1.62 1.50 1.77 1.98

v -4.45 2.73 -4.79 2.83 -4.13 2.67

L1A X 2.12 2.03 2.37 2.08 1.88 2.01

v -4.33 2.89 -4.20 3.11 -4.45 2.76

LM X 2.31 1.46 2.18 1.31 2.43 1.62

v -3.85 2.93 -3.73 3.20 -3.96 2.73 AppBNoIcBs 230

ACT Total Males Females landmark MEAN SD MEAN SD MEAN SD

Pog X 1.53 2.O3 1.51 1.80 1.54 2.28

v -6.12 3.85 -6.20 4.20 -6.04 3.60

Gn x 1.64 2.33 1.73 2.31 1.55 2.40

v -5.55 3.67 -5.75 3.98 -5.36 3.46

Me X 1.38 2.81 1.21 2.67 1.53 3.00

v -5.53 3.72 -5.83 4.13 -5.24 3.39

Go X -0.49 1.90 -0.84 1.57 -0.16 2.16

v -3.87 3.26 -4.22 3.74 -3.55 2.80

Ar X -1 .18 1.45 -1.42 1.45 -0.95 1.45

v -0.99 2.01 -1.30 2.45 -0.70 1.49

Co X -1.00 1.75 -1.09 1.88 -0.92 1.67

v -0.95 2.63 -1.80 2.98 -0.15 2.03

PTM X -0.39 1.07 -0.44 1.04 -0.35 1.12

v -0.24 1.73 -0.53 1.89 0.03 1.56

Ba X -1.08 1.81 -1.33 1.60 -0.85 2.00

v -1.14 3.59 -0.63 2.35 -1.61 4.48 ApppNorces 231

Table 45 Cranial Base Superimposition- treatment changes for activator / headgear soft tissue landmarks.

ACT Total Females

landmark MEAN SD SD MEAN SD

STN x 1.36 1.69 1.72 1.98 1.O2 1.33

v -0.59 2.95 -1.1 3 2.78 -0.09 3.09

Ntip x 2.49 2.67 2.79 3.46 2.21 1.68

v -2.59 2.52 -2.74 2.39 -2.45 2.69

Snx 1.19 1.71 1.42 2.05 0.98 1.33

v -2.76 2.58 -2.92 2.66 -2.61 2.58 Ssx 0.13 1.97 0.42 2.20 -0.15 1.74

v -3.23 3.22 -3.70 3.32 -2.78 3.16 Lsx -o.42 2.52 -0.35 3.22 -0.48 1.70

v -3.68 3.22 -4.24 3.18 -3.16 3.26

ULL X -o.76 2.30 -0.90 2.72 -0.63 1.90

v -3.12 3.22 -3.66 3.47 -2.60 2.96

LLH X 1.41 3.41 1.35 3.53 1.46 3.40

v -1.56 3.92 -2.08 3.80 -1.06 4.07 Li x 1.58 2.72 1.34 2.66 1.80 2.83

v -2.61 4.09 -2.92 3.64 -2.32 4.55

Si x 3.04 2.32 2.75 1.94 3.31 2.65

v -3.63 4.28 -4.49 4.42 -2.83 4.10

ST Pog x 2.19 2.55 2.35 2.34 2.04 2.80

v -5.41 4.52 -5.68 4.70 -5.15 4.46

STMe X 1.29 2.82 1.19 2.72 1.38 2.98

v -5.57 4.05 -6.11 4.68 -5.05 3.42 AppBN¡IcBs 232

Table 46 Cranial Base Superimposition- treatment changes for the Glark Twin Block hard tissue landmarks.

CTB. Total Males Females landmark MEAN SD MEAN SD MEAN SD

S X -0.04 0.54 -0.09 0.66 0.04 0.34

v 0.07 0.79 0.13 0.90 0.00 0.6s

N X 0.90 1.22 1.07 1.43 0.68 0.88

v 0.20 1.57 0.43 1.53 -0.10 1.63

Or X 0.33 1.21 0.46 0.99 0.15 1.47

v 0.10 1.19 0.24 1.36 -0.07 0.95

Po X -0.31 0.99 -o.29 1.10 -0.34 0.87

v -0.10 1.06 -0.09 1.11 -o.12 1.04

A X o.42 1.69 0.93 1.54 -0.25 1.70

v -1.65 1.72 -1.69 1.92 -1.59 1.49

B X 2.42 2.71 3.03 2.81 1.62 2.45

v -4.91 2.78 -4.81 2.96 -5.05 2.64

ANS X 0.96 2.10 1.63 1.67 0.08 2.33

v -1.26 1.83 -1.33 1.90 -1.17 1.81

PNS X -o.23 2.00 -0.07 1.65 -0.45 2.43

v -0.89 1.37 -1.O1 1.70 -0.73 o.78

U1E X -1.54 2.56 -1.02 2.82 -2.22 2.O8

v -2.68 1.80 -2.84 2.16 -2.47 1.24

U1A X 0.93 1.80 1.27 2.22 0.49 0.97

v -1.22 2.04 -1.41 2.33 -0.97 1.65

UM X -0.45 1.66 -0.24 1.88 -0.72 1.35

v -1.49 1.95 -1.76 1.81 -1.13 2.14

L1E x 3.62 2.22 4.02 1.93 3.09 2.53

v -4.83 2.08 -4.81 2.22 -4.86 1.96

L1A X 2.43 2.56 2.89 2.80 1.83 2.18

v -4.28 1.91 -4.39 1.88 -4.14 2.01

LM X 3.92 1.93 3.92 1.98 3.93 1.93

v -3.37 '1.63 -3.45 1.81 -3.27 1.43

Pog X 2.39 2.64 3.05 2.83 1.53 2.19

v -4.65 1.76 -4.79 1.65 -4.47 1.95 ApppNorces 233

CTB. Total Males Females landmark MEAN SD MEAN SD MEAN SD

Gnx 2.34 2.72 2.79 2.95 1.74 2.36

v -4.30 1.66 -4.48 1,81 -4.06 1.46

Me X 2.54 2.68 2.98 2.72 1.97 2.63

v -4.45 1.75 -4.58 1.97 -4.29 1.49

Go x 0.62 1.53 0.95 1.47 0.18 1.57

v -3.20 2.13 -3.38 2.29 -2.96 1.97 Ar x -0.49 0.99 -o.47 1.05 -0.53 0.94

v -0.51 1.09 -0.76 1.17 -0.19 0.92

Co X -0.41 1.53 -0.67 1.57 -0.08 1.46

v -0.69 1.89 -0.28 1.91 -1.24 1.80

PTM X 0.03 0.72 0.00 0.85 0.08 0.55

v -0.09 1 .15 -0.30 1.31 0.19 0.88

Ba x -0.68 0.94 -0.77 0.99 -0.56 0.89

v -o.45 1.53 -0.61 1.53 -0.24 1.57 AppnNrrcBs 234

Table 47 Granial Base Superimposition- treatment changes for the Glark Twin Block soft tissue landmarks.

CTB. Total Males Females landmark MEAN SD MEAN SD MEAN SD

STN X 0.90 1.80 1.21 2.02 0.49 1.44

v 0.59 2.41 0.63 1.77 0.52 3.13

Ntip x 1.89 2.O1 2.44 2.30 1.18 1.34

v -1.39 2.01 -1.31 1.91 -1.49 2.21 Snx 1.08 2.07 1.62 2.25 0.37 1.62

v -1.75 1.80 -1.94 1.98 -1.50 1.58 Ssx o.52 2.14 1.41 2.04 -0.65 1.70

v -2.74 2.54 -3.21 2.65 -2.13 2.37 Lsx -0.11 2.50 0.67 2.70 -1.13 1.85

v -2.19 2.06 -2.68 2.38 -1.55 1.37

ULL X o.14 2.57 1.34 2.47 -1.43 1.76

v -2.13 2.17 -2.37 2.58 -1.82 1.55

LLH X 3.12 3.94 4.20 3.79 1.72 3.82

v -0.97 1.95 -1.30 1.71 -0.54 2.21 Li x 3.06 3.18 4.O7 2.74 1.74 3.32

v -1.34 2.45 -1.31 1.88 -1.38 3.12 Si x 4.18 3.11 5.08 2.89 s.01 3.10

v -2.48 2.79 -1.89 2.29 -3.25 3.27

ST Pog x 3.18 3.26 3.95 3.29 2.16 3.04

v -3.26 3.45 -3.49 3.10 -2.96 3.98 STMe x 2.43 2.78 3.11 2.87 1.55 2.49

v -4.13 2.O2 -4.52 2.20 -3.61 1.69 AppBNnrcss 235

Table 48 Granial Base Superimposition- treatment changes for the Fränkel hard tissue landmarks.

FRÄNKEL Total Males Females landmark MEAN SE MEAN SD MEAN SD

S x 0.o2 0.58 0.14 o.42 -0.11 0.71

'1.30 v -o.14 1.04 o.12 0.67 -0.42

N X o.92 1.30 0.95 0.93 0.90 1.64

v 0.20 1.35 0.61 1.28 -0.23 1.34

Or X o.28 1.85 0.08 1.55 0.48 2.17

v -0.63 1.43 -0.35 1.28 -0.93 1.56

Po X -o.72 1.24 -0.33 0.71 -1.13 1.56

v -0.28 1.37 -0.21 0.93 -0.35 1.76

A x 0.64 1.52 0.93 1.40 0.34 1.64

v -2.41 2.23 -2.O3 2.09 -2.82 2.37

B X 1.68 2.12 2.31 1.97 1.00 2.12

v -5.27 2.22 -5.61 2.48 -4.90 1.94

ANS X 1.03 1.96 1.43 1.94 0.6'l '1.96

v -2.O1 2.00 -1.45 1.67 -2.62 2.19

PNS X 0.30 2.01 0.78 2.20 -0.21 1.71

v -1.52 1.54 -1.48 1.70 -1.56 1.41

U1E X -1.84 2.06 -1.57 2.19 -2.12 1.96

v -2.72 1.88 -2.59 1.86 -2.86 1.96

U1A X 1.15 1.95 1.67 2.06 0.60 1.73

v -1.86 1.92 -1.51 1.38 -2.24 2.36

UM X 0.43 2.39 0.60 2.25 o.24 2.61

v -2.74 2.60 -2.40 3.16 -3.10 1.89

L1E x 2.66 2.09 3.54 2.19 1.71 1.52

v -5.43 2.10 -5.72 2.51 -5.12 1.59

L1A x 2.03 2.55 2.44 2.26 1.60 2.86

v -4.68 2.43 -5.19 3.06 -4.14 1.40

LM X 3.28 2.17 3.69 2.18 2.84 2.15

v -3.95 2.18 -3.64 2.57 -4.28 1.72

Pog X 1.46 2.35 2.19 2.O8 0.67 2.44

v -5.44 2.31 -5.34 2.79 -5.56 1.76 AppBNnrcns 236

FRÄNKEL Males Females landmark SD MEAN SD MEAN SD

Gnx 1.48 2.40 2.09 2.26 0.82 2.46

v -5.58 2.45 -5.63 3.04 -5.52 1.84

Me X 1.07 2.58 't.94 2.25 0.13 2.65

v -5.46 2.40 -5.42 2.86 -5.52 1.89

Go x -0.38 1.51 0.12 1.45 -0.91 1.43

v -4.15 2.37 -4.32 2.33 -3.96 2.48

Ar x -0.96 1.09 -0.90 1.05 -1.02 1.17

v -1.26 1.45 -1.01 1.29 -1.53 1.60

Co x -0.71 1.93 -o.47 2.29 -0.98 1.50

v -0.9ô 2.26 -1.07 2.32 -0.84 2.27

PTM x -0.16 0.87 -0.21 0.92 -0.11 0.84

v -0.55 1.77 0.18 1.00 -1.33 2.10

Ba X -0.76 1.30 -0.63 1.41 -0.90 1.21

v -0.91 1.42 -1.09 1.42 -o.72 1.46 AppeNorcns 237

Table 49 Granial Base Superimposition- treatment changes for the Fränkel soft tissue landmarks.

FRÄNl(EL Total Males Females fandmark MEAN SD MEAN SD MEAN SD

STN X 0.81 1.85 1.03 '1.36 0.58 2.29

v 0.38 2.21 1.02 1.50 -0.30 2.67 Ntip x 2.32 2.74 2.52 2.38 2.10 3.16

v -2.10 1.77 -1.64 1.44 -2.59 2.00 Snx 1.16 2.60 1.74 1.75 0.54 3.24

v -2.50 2.02 -1.92 1.45 -3.13 2.40 Ssx 0.58 2.38 1.11 1.99 o.o2 2.69

v -3.47 2.97 -2.80 3.15 -4.20 2.69 Lsx -0.07 2.49 0.32 2.16 -0.49 2.82

v -2.97 2.11 -2.87 1.74 -3.O7 2.51 ULL x -0.12 2.69 -0.08 1.91 -0.16 3.42

v -2.92 2.39 -3.05 2.30 -2.78 2.56

LLH X 1.82 2.85 2.69 2.60 0.88 2.90

v -1.74 2.O2 -1.47 2.34 -2.03 1.65

Li x 1.81 2.87 2.73 2.94 o.82 2.54

v -2.29 2.18 -1.83 2.58 -2.78 1.59 Si x 3.43 2.13 4.11 2.04 2.70 2.O5

v -4.08 2.93 -4.44 3.56 -3.69 2.13 ST Pog x 2.66 3.09 3.58 2.89 1.67 3.08

v -4.78 2.90 -4.44 3.59 -5.15 2.00

STMC X 1.00 2.70 1.92 2.48 0.00 2.64

v -5.61 2.69 -5.69 3.22 -5.52 2.11

A positive change denotes an anterior movement of the landmark in the x-axis and superior movement in the y-axis. AppnNorcns 238

8.5 Summary of significant differences between males and females pre- and post-treatment.

Table 50 Significant differences between males and females pre-treatment.

PreTx M vs F

Variable

SN-FH

LOP

L1-MP

Co-Gn

Ar-Gn

Co-Go

LFH

N-Me

S-Go

A-Svert

OJ

OB

Ls-A

ST TFH

ST UFH

ST LFH

LLL

STP-STN

Sn-Svert

SsSvert

LsSvert

(*) significant at p<0.05

(* *) significant at p<0.01

(** *) significant at p<0.001 AppBNnrcns 239

Table 51 Significant differences between males and females post-treatment.

PostTx M vs F

Variable ACT

MaxPl-SN

Co-A

L1-MP

Co-Gn

Ar-Gn

Co-Go

Ar-Go

UFH

LFH

UFHLFH

N-Me

S-Go

A-Sveft

L-Mfold

Ls-A

ST TFH

ST LFH

ULL

LLL

Sn-Svert

SsSvert

LsSvert

LiSvert

(*) significant at p<0.05

(* *) signihcant at p<0.01

(***) significant at p<0.001 ApppNotc¡s 240

8.6 Comparison with untreated subjects

An initial comparison of the ages was made between the Illing et al. (1998) and Morris et al. (1998) control groups with the treatment groups. There were no signif,rcant differences between the ages of the groups,

Table 52 Age comparison of the three functional appliance groups with the llling et al (f 998) and Morris et al. (1998) control group.

The activator with combination high-pull headgear:

MALES GONTROL N=13 ACT N=17 Control vs Act

PreTx: MEAN SD MEAN SD F-ratio T value T prob

AGE 11.7 1.75 11.2 1.71 1.05 0.79 0.4445

FEMALES CONTROL: N=7 ACT N=1 8 Control vs Act

PreTx: MEAN SD MEAN SD F-ratio T value T prob

AGE 10.3 1.34 11.0 1.72 1 .65 0.90 0.3833

The Clark Twin Block:

MALES CONTROL N=13 CTB N=17 Control vs CTB

PreTx MEAN SD MEAN SD F-ratio T value T prob

AGE 11.7 1.75 10.7 1.61 1.11 1 .60 0.1 181

FEMALES CONTROL: N=7 CTB N=1 3 Control vs CTB

PreTx: MEAN SD MEAN SD F-ratio T value T prob

AGE 10.3 1.34 10.5 1.09 1.51 0.36 0.7217

The Fränkel MALES CONTROL N=13 FRÄNKEL N=15 Control vs Fränkel

PreTx: MEAN SD MEAN SD F-ratio T value T prob

AGE 11.7 1.75 10.9 1.56 1.26 1.17 0.2525

FEMALES CONTROL N=7 FRÄNKEL N=14 Gontrol vs Fränkel

PreTx: MEAN SD MEAN SD F-ratio T value T prob

AGE 10.3 1.34 10.7 1.O2 1.73 0.84 0.4158 AppsNorcss 24r

Table 53 Control comparison with the pre-treatment male activator group

MALES CONTROL N=13 ACT N=17 Control vs Act

PreTx: MEAN SD MEAN SD F-ratio T value T prob

SNA 80.6 4.53 81.5 3.35 1.83 0.58 0.5747

ANB 6.9 1.58 5.6 1.61 1.04 2.21 0.0335

SNB 73.7 4.38 75.8 3.30 1.76 1.53 0.1342

Co-Gn 102.1 6.80 104.0 4.69 2.10 0.91 0.3733

Ar-Gn 95.6 6.10 96.0 3.90 2.45 0.23 0.8135 *" UFH 49.1 4.80 47.8 2.28 4.43 0.88 0.3952

LFH 56.1 5.29 61.9 4.17 1.61 3.37 0.0025 * N-Me 105.2 8.50 107.0 5.22 2.65 0.69 0.5065

A-Svert 63.5 4.68 65.9 4.23 1.22 1.47 0.1491

B-Svert 51.0 7.21 56.0 6.18 1.36 2.06 0.0459

PogSvert 51.4 8.22 56.3 6.78 1.47 1.75 0.0871

OJ 10.2 2.53 7.6 2.18 1.35 3.09 0.0047

OB 6.2 2.60 5.4 1.68 2.40 1.06 o.2982

F.conv 131 .6 5.71 128.0 3.96 2.08 2.05 0.0476

N-Lang 123.9 10.72 124.0 10.44 1.05 0.03 0.9761

L-Mfold 1 15.9 15.70 1 18.3 13.29 1.40 0.45 0.6619

Ls-A 17.0 1.63 21.1 1.83 1.26 6.42 0.0000

Li-B 19.6 4.68 21.8 3.26 2.06 1.57 0.1248

ST TFH I 13.8 8.33 112.2 6.09 1.87 o.62 o.5446

ST UFH 53.7 5.66 48.5 4.26 1.77 2.84 0.0083

ST LFH 60.'1 4.06 69.0 4.60 1.28 5.51 0.0000

STLFH% 52.9 2.38 61.5 2.51 1.11 9.54 0.0000

Ls-E '1.60 2.34 1.3 1.59 2.17 0.49 0.6346

L¡-E 0.30 4.03 1.4 2.15 3.51 " 0.89 0.3886

ULL 18.6 1.59 20.6 2.20 1.93 2.81 0.0087

LLL 37.1 2.73 44.6 3.95 2.09 5.83 0.0000

Sn-Svert 78.6 4.29 80.7 4.56 1 .13 1.26 0.2146

SsSvert 77 1 4.46 80.0 4.95 1.23 1.65 0.1072

LsSvert 80.5 5.26 82.9 4.91 1.15 1.31 0.1989

LiSvert 70.5 6.68 76.3 6.16 '1.18 2.45 0.0198

SiSvert 60.8 7.34 66.1 6.48 1.28 2.09 0.0431

STPSvert 62.4 7.73 67.0 7.90 1.04 1.60 o.1184 AppBNotces 242

Table 54 Control comparison with the pre-treatment female activator group

FEMALES CONTROL: N=7 ACT N=1 8 Control vs Act

PreTx: MEAN SD MEAN SD F-ratio T value T prob

SNA 82.1 3.40 82.0 3.76 1.22 0.06 0.9554

ANB 6.8 3.25 6.0 1.98 2.69 0.62 0.5552

SNB 75.3 1.61 76.0 2.83 3.09 0.65 0.5307

Co-Gn 97.1 6.00 100.7 5.55 1.17 1.43 0.1 633

Ar-Gn 91.3 5.10 93.6 5.84 1.31 0.9'l o.3776

UFH 46.0 1.85 47.1 3.13 2.86 0.87 0.3953 ** LFH 52.7 7.34 60.5 3.18 5.33 2.72 0.0287 * N-Me 98.6 6.90 104.7 3.64 3.59 2.21 0.0613

A-Svert 62.5 4.62 62.9 4.83 1.09 o.20 0.8357

B-Svert 51.9 3.76 53.1 5.93 2.49 0.49 0.6336

PogSvert 52.2 4.30 52.9 6.60 2.36 0.25 0.802

OJ 10.7 2.30 7.8 1.89 1.48 3.25 0.0038

OB 4.4 2.60 4.0 1.95 1.78 0.41 0.6884

F.conv 131.3 6.06 128.1 3.94 2.37 1.58 o.1242

N-Lang 122.9 8.08 124.3 10.17 1.58 0.32 0.7481

L-Mfold 125.6 20.09 126.9 16.87 1.42 o.17 0.8592

Ls-A 17.0 1.18 19.9 1.87 2.51 3.78 0.0013

Li-B 19.1 3.56 21.2 2.47 2.O8 1.65 0.1099

ST TFH 108.5 5.38 108.5 3.71 2.1 0.01 0.9881

ST UFH 50.4 1.98 45.6 3.45 3.04 3.47 0.0024

ST LFH 58.1 5.13 67.9 3.17 2.62 5.83 0.0000

STLFH% 53.5 2.41 62.6 2.52 1.11 8.19 0.0000

Ls-E 2.7 2.54 1.1 2.O5 1.54 1.66 0.1067

Li-E 1.5 2.17 0.5 2.44 1.26 0.90 0.3815

ULL 17.7 2.25 20.0 2.48 1.21 2.14 0.0408

LLL 37.2 4.51 44.6 3.47 1.69 4.44 0.0004

Sn-Svert 76.9 3.71 76.2 4.62 1.55 0.35 0.7313

SsSvert 76.2 3.73 76.0 5.15 1.91 0.09 0.9237

LsSvert 79.5 4.O7 78.5 5.55 1.86 0.42 0.6823

LiSvert 71.0 3.93 72.1 6.44 2.69 0.43 0.6768

SiSvert 61.7 4.97 63.3 5.93 1.42 0.63 0.5385

STPSvert 61.5 3.98 64.0 7.46 3.51 0.81 0.4292 AppeNolcrs 243

Table 55 Gontrol comparison with the pre-treatment male Glark Twin Block group

MALES CONTROL N=13 CTB N=17 Control vs CTB

PreTx: MEAN SD MEAN SD F-ratio T value T prob

SNA 80.6 4.53 80.9 3.s3 1.63 0.18 0.8545

ANB 6.9 1.58 5.6 2.27 2.06 1.79 0.0812

SNB 73.7 4.38 75.3 3.66 1.43 1.08 0.2911

Co-Gn 102.1 6.80 103.4 6.98 1.03 o.52 0.6108

Ar-Gn 95.6 6.10 96.5 6.27 1.06 0.41 0.6863

UFH 49.1 4.80 48.0 2.87 2.80 0.73 0.4838 ** LFH 56.1 5.29 61.0 4.09 1.67 2.85 0.0080

N-Me 105.2 8.50 106.3 5.81 2.14 0.43 0.6720

A-Sveft 63.5 4.68 65.1 3.70 1.6 1.02 0.3172

B-Svert 51.0 7.21 55.2 5.73 1.58 1.79 0.0805

PogSvert 51.4 8.22 55.6 6.95 1.41 1.52 0.1368

OJ 10.2 2.53 8.5 2.55 1.02 1.87 0.0689

OB 6.2 2.60 5.3 2.32 1.26 1.03 0.3114 * F.conv 131 .6 5.71 127.4 4.55 1.57 2.23 0.0318

N-Lang 123.9 10.72 125.4 7.81 1.88 0.45 0.6623

L-Mfold 1 15.9 15.70 117.9 9.51 2.73 " o.42 0.6845 *** Ls-A 17.0 1.63 20.1 2.30 1.99 4.20 0.0004

Li-B 19.6 4.68 20.8 2.13 4.83 "* 0.90 0.3839

ST TFH 1 '13.8 8.33 111.3 6.52 1.63 0.93 0.3608 * ** ST UFH 53.7 5.66 46.9 3.39 2.79 3.84 0.0015 *** ST LFH 60.1 4.06 69.9 5.13 1.60 5.62 0.0000 *** STLFH% 52.9 2.38 62.8 2.04 1.36 12.20 0.0000

Ls-E 1.6 2.34 0.8 2.O4 1.32 1.04 0.3097

Li-E 0.3 4.03 0.0 2.28 3.12* 0.29 o.7727 ** ULL 18.6 1.59 20.6 2.12 1.78 2.87 0.oo77 *** LLL 37.1 2.73 45.1 2.42 1.27 8.50 0.0000

Sn-Svert 78.6 4.29 79.6 4.19 1.05 0.62 0.5499

SsSvert 77.1 4.46 78.6 4.59 '1.06 0.89 0.3870

LsSvert 80.5 5.26 81.8 5.23 1.01 0.69 0.4997

LiSvert 70.5 6.68 74.6 5.36 11.55 1.86 0.0699

SiSvert 60.8 7.34 65.0 6.02 1.49 1.73 0.091

STPSvert 62.4 7.73 67.2 7.32 1.12 1.74 0.0898 AppBNoIcss 244

Table 56 Control comparison with the pre-treatment female Glark Twin Block group

FEMALES GONTROL: N=7 CTB: N=1 3 Control vs CTB

PreTx MEAN SD MEAN SD F-ratio T value T prob

SNA 82.1 3.40 81.5 3.27 1.08 0.33 o.7404

ANB 6.8 3.25 6.1 2.17 2.24 0.59 0.5708

SNB 75.3 1.61 75.4 2.89 3.22 0.16 0.8691

Co-Gn 97.1 6.00 99.5 3.91 2.35 1.09 0.2896

Ar-Gn 91.3 5.10 92.5 3.77 1.83 0.59 0.5682

UFH 46.0 1.85 46.8 1.65 1.26 1.08 o.2949 * LFH 52.7 7.34 58.3 3.64 4.O7 1.90 0.0912

N-Me 98.6 6.90 102.3 3.64 3.59 1.33 o.2176

A-Sved 62.5 4.62 64.3 3.55 11.69 0.97 0.3471

B-Svert 51.9 3.76 54.4 4.89 1.69 1.19 0.2493

PogSvert 52.2 4.30 54.6 5.78 1.8'l 0.94 0.3622 * OJ 10.7 2.30 8.2 2.59 1.27 2.08 0.0492

OB 4.4 2.60 4.8 1.86 1.95 o.41 0.6891 * F.conv 131.3 6.06 126.7 3.82 2.52 2.10 0.0479

N-Lang 122.9 8.08 126.2 9.56 1.40 o.77 0.4562

L-Mfold 125.6 20.09 122.8 13.17 2.33 0.37 0.7'136 * Ls-A 17.O 1.18 19.2 2.10 3.17 2.61 0.0168

Li-B 19.1 3.56 19.4 2.79 1.63 0.20 0.8365

ST TFH 108.5 5.38 106.8 4.86 1.23 o.72 0.4900 ** ST UFH 50.4 1.98 46.4 3.26 2.71 2.93 0.0088 ** ST LFH 58.1 5.13 65.4 4.03 1.62 3.51 0.0028 *** STLFH% 53.5 2.41 61.2 2.57 1.14 6.55 0.0000

Ls-E 2.7 2.54 0.1 2.60 1.05 2.10 0.0477 i

Li-E 1.5 2.17 -0.6 3.16 2.12 1.55 0.1361

ULL 17.7 2.25 19.5 1.86 1.46 1.95 0.0637 ** LLL 37.2 4.51 42.3 2.99 2.26 3.08 0.0065

Sn-Svert 76.9 3.71 77.6 3.69 1.01 o.43 0.6734

SsSvert 76.2 3.73 76.9 3.54 1.11 0.43 0.6739

LsSvert 79.5 4.07 79.3 4.43 1.18 0.09 0.9233

LiSvert 71.O 3.93 72.6 3.82 1.06 0.89 0.3887

SiSvert 61.7 4.97 64.2 3.95 1.58 11.22 o.2384

STPSvert 61.5 3.98 65.2 6.52 2.68 1.35 0.1912 AppBNorcss 245

Table 57 Gontrol comparison with the pre-treatment male Fränkel group

MALES CONTROL N=13 FRÄNKEL N=15 Control vs Fränkel

PreTx: MEAN SD MEAN SD F-ratio Tvalue Tprob

SNA 80.6 4.53 81.8 3.57 1.61 0.80 0.4385

ANB 6.9 1.58 b.þ 2.47 2.44 0.38 o.711

SNB 73.7 4.38 75.2 2.64 2.75 " 1.09 0.2889

Co-Gn 102.1 6.80 101 .8 3.77 3.25* 0.15 0.8802

Ar-Gn 95.6 6.10 93.9 4.05 2.27 0.91 0.3768

UFH 49.1 4.80 47.6 2.68 3.21 " 1.03 0.3163

LFH 56.1 5.29 60.0 3.52 2.26 2.31 0.0273

N-Me 105.2 8.50 104.5 3.25 6.84*** o.26 0.7910

A-Svert 63.5 4.68 65.8 4.14 1.28 1.37 0.1 800

B-Svert 51.0 7.21 54.8 5.07 2.O2 1.65 0.1079

PogSvert 51.4 8.22 55.0 6.02 1.86 1.37 0.1791

OJ 10.2 2.53 8.2 2.25 1.26 2.21 0.0338

OB 6.2 2.60 6.2 2.44 1.14 0.05 0.9575

F.conv 131 .6 5.71 126.7 3.60 2.52 2.78 0.0096

N-Lang 123.9 10.72 128.4 6.96 2.37 1.34 0.1888

L-Mfold 1 '15.9 15.70 122.4 12.69 1.53 1.22 0.2328

Ls-A 17.O 1.63 19.9 1.73 1.13 4.61 0.0002

Li-B 19.6 4.68 21.5 2.58 3.29" 1.33 0.1979

ST TFH 1 '13.8 8.33 108.7 3.54 5.54 "* 2.O3 0.0565 *** ST UFH 53.7 5.66 47.O 1.83 9.57 4.04 0.0015

ST LFH 60.1 4.06 67.2 3.66 1.23 4.83 0.0002

STLFH% 52.9 2.38 61.8 1.95 1.49 10.82 0.0000

Ls-E 1.6 2.34 1.4 1.86 1.58 0.25 0.7984 ** Li-E 0.3 4.03 0.7 2.02 3.98 0.31 0.7591

ULL 18.6 1.59 20.4 1.57 11.03 3.06 0.0052

LLL 37.1 2.73 43.6 2.69 1.03 6.40 0.0000

Sn-Svert 78.6 4.29 80.0 3.82 1.26 0.88 0.3903

SsSvert 77.1 4.46 78.7 3.94 1.28 1.01 0.3209

LsSvert 80.5 5.26 81.8 3.83 1.89 o.74 0.4705

LiSvert 70.5 6.68 74.8 3.97 2.83* 2.00 0.0575

SiSvert 60.8 7.34 65.2 4.75 2.39 1.9 0.0649

STPSvert 62.4 7.73 66.0 6.43 1.45 1.35 0.1 873 AppBNNICBS 246

Table 58 Gontrol comparison with the pre-treatment female Fränkel group

FEMALES CONTROL N=7 FRÄNKEL N=I4 Control vs Fränkel

PreTx MEAN SD MEAN SD F-ratio T value T prob

SNA 82.1 3.40 80.9 2.64 1.66 0.89 0.3864

ANB 6.8 3.25 6.0 1.78 3.33 " 0.64 0.5467

SNB 75.3 1.61 74.9 2.76 2.94 o.32 o.7528

Co-Gn 97.1 6.00 98.5 4.91 1.49 0.57 0.5823

Ar-Gn 91.3 5.10 92.1 5.66 1.23 0.30 o.7624

UFH 46.0 1.85 47.2 2.40 1.68 1.23 0.2306

LFH 52.7 7.34 57.2 3.27 5.04 1.57 o.1574 * N-Me 98.6 6.90 102.0 3.99 2.99 1.22 0.2570

A-Svert 62.5 4.62 62.5 3.91 1.40 0.01 0.9916

B-Svert 51.9 3.76 52.O 5.42 2.08 0.07 0.9471

PogSvert 52.2 4.30 51.8 5.94 1.91 0.16 0.8706

OJ 10.7 2.30 6.2 0.97 5.62"" 4.96 0.0020

OB 4.4 2.60 4.9 2.29 1.29 0.49 0.6362

F.conv 131.3 6.06 127.3 3.48 3.03 " 1.60 0.1465

N-Lang 122.9 8.08 127.9 9.79 1.47 '1.16 o.261

L-Mfold 125.6 20.09 126.5 8.37 5.76',* 0.27 0.793

Ls-A 17.0 1.18 18.7 1.45 1.51 3.56 0.0016

Li-B 19.1 3.56 22.2 1.81 3.87 2.13 0.0642

ST TFH 108.5 5.38 105.4 6.35 '1.39 1.09 0.2891 * ST UFH 50.4 1.98 45.6 4.22 4.54 3.54 0.0025

ST LFH 58.1 5.13 64.9 4.16 1.52 3.29 0.0040

STLFH% 53.5 2.41 61.6 2.32 1.08 7.48 0.0000

Ls-E 2.7 2.54 0.6 1.63 2.43 2.23 0.0358

Li.E 1.5 2.17 1.1 1.94 1.25 0.43 0.6759

ULL 17.7 2.25 19.9 1.94 1.35 2.28 0.0323

LLL 37.2 4.51 43.2 4.16 1.18 3.04 0.0068

Sn-Svert 76.9 3.71 76.2 4.04 1.19 0.38 0.7101

SsSvert 76.2 3.73 75.0 4.26 1.30 0.66 o.5245

LsSvert 79.5 4.O7 77.4 5.53 1.85 0.86 0.4062

LiSved 71.O 3.93 72.1 5.43 1.91 0.47 0.6506

SiSvert 61.7 4.97 62.4 5.35 1.16 0.30 0.7665

STPSvert 61.5 3.98 63.0 5.83 2.15 0.61 0.5s84 AppBNntcBs 247

Table 59 Gontrol comparison with the post-treatment male activator group

MALES CONTROL N=13 ACT N=1 7 Control vs ACT

Post Tx MEAN SD MEAN SD F-ratio T value T prob

SNA 81.0 4.46 81.4 3.37 1.75 0.32 0.753

ANB 7.5 1.47 5.1 1.57 1.14 4.28 0.0004

SNB 73.5 4.70 76.3 3.27 2.07 1.97 0.0563

Co-Gn 103.0 6.70 106.0 4.79 1.96 1.45 0.1547

Ar-Gn 96.9 6.10 98.4 4.30 2.01 0.81 0.4322 ** UFH 50.3 4.80 48.9 2.33 4.24 0.95 0.3600

LFH 55.4 4.58 63.1 4.47 1.05 4.61 0.0002

N-Me 105.7 8.50 109.4 5.75 2.19 1.44 0.1 573

A-Svert 64.2 4.41 66.2 4.29 1.06 1.24 0.2218

B-Svert 50.7 7.59 56.8 6.14 1.53 2.43 0.0207

PogSvert 5'1.3 8.68 57.0 6.86 1.60 2.01 0.0513

OJ 11.0 2.99 5.7 1.97 2.30 5.80 0.0000 ** OB 6.5 3.'10 4.1 1.63 3.62 2.55 0.0198

F.conv 130.3 6.23 128.5 3.85 2.62 0.93 0.3659

N-Lang 123.4 9.18 126.7 7.67 1.43 1.09 o.2854

L-Mfold 1 16.3 17.14 124.4 12.22 1.97 3.38 0.0025

Ls-A 16.4 2.04 21.0 1.42 2.O9 7.34 0.0000

Li-B 20.4 3.46 22.0 2.35 2.17 1.54 0.1 320

ST TFH 115.0 8.04 114.2 6.05 1.77 0.31 o.7584

ST UFH 55.2 4.78 49.2 3.80 1.58 3.82 0.0010

ST LFH 59.9 3.86 70.2 4.59 1.41 6.58 0.0000

STLFH% 52.1 1.42 61.5 2.17 2.34 13.57 0.0000

Ls-E 1.3 2.44 0.0 1.56 2.45" 1.70 o.1017

Li-E -o.4 2.92 o.7 2.14 '1.86 1.14 0.2639

ULL 18.9 2.75 21.2 1.97 1.95 2.70 0.o114

LLL 38.5 3.11 46.1 3.91 1.58 5.80 0.0000

Sn-Svert 78.9 4.87 81.2 4.73 1.06 1.31 0.1 987

SsSvert 77.6 5.01 80.0 5.03 1.01 1.30 0.2008

LsSvert 80.6 6.'11 82.5 5.10 1.44 0.95 0.3536

LiSvert 71 .1 6.27 76.8 5.6'l 1.25 2.62 0.0135

SiSvert 61.5 7.51 67.4 6.45 1.36 2.31 0.o27

STPSvert 63.1 8.62 68.0 8.01 1.16 1.60 0.1172 APPENDICES 248

Table 60 Gontrol comparison with the post-treatment female activator group

FEMALES CONTROL N=7 ACT N=1 8 Control vs ACT

Post Tx: MEAN SD MEAN SD F-ratio T value T prob

SNA 82.2 3.18 81.8 3.84 1.46 0.24 0.8088

ANB 7.O 3.13 5.0 1.86 2.83* 1.54 0.1 606

SNB 75.2 1.67 76.7 3.10 3.45 1.24 0.2273

Co-Gn 99.1 5.20 103.3 5.56 1.14 1.73 0.0939

Ar-Gn 91.7 4.70 96.0 6.45 1.88 1.58 0.1246

UFH 46.3 2.O4 47.4 2.77 1.84 1.01 0.3241

LFH 53.1 7.05 62.0 3.35 4.43 "* 3.21 0.0146 * N-Me 99.3 6.90 106.8 3.64 3.59 2.72 0.0288

A-Svert 63.5 4.71 62.9 4.82 1.05 0.30 o.7675

B-Svert 52.7 4.37 54.0 6.30 2.08 0.53 0.6104

PogSvert 53.4 4.58 53.7 7.22 2.49 0.10 0.9139 ** OJ 11.2 2.83 5.0 1.25 5.1 3 5.60 0.0012 * OB 4.3 2.90 3.2 1.66 3.05 0.97 0.3622

F.conv 128.9 6.36 128.7 4.31 2.18 0.11 0.9064

N-Lang 123.7 7.82 125.7 9.54 1.49 0.51 0.6208

L-Mfold 123.2 11.00 133.9 14.29 1.69 1.79 0.0839

Ls-A 17.2 1.13 20.0 1.57 1.93 4.24 0.0005

Li-B 19.5 3.06 21.8 1.97 2.41 2.25 o.0324

ST TFH 107.7 6.51 1 10.8 4.25 2.35 1.43 0.1627

ST UFH 50.5 2.30 46.8 3.34 2.11 2.64 0.0140 * ST LFH 57.2 6.62 68.9 3.55 3.48 4.44 0.0034

STLFH% 53.0 3.28 62.2 2.34 1.96 7.89 0.0000

Ls-E 2.6 1.80 -0.3 1.91 1.13 3.40 o.oo27

Li-E 0.8 3.07 0.2 2.38 1.66 0.57 0.5774

ULL 17.5 2.12 20.1 2.13 1.01 2.81 0.0097

LLL 37.0 3.26 46.6 3.17 1.06 6.79 0.0000

Sn-Svert 78.1 4.02 76.6 5.01 1.55 o.72 0.4883

SsSvert 77.5 3.96 75.9 5.34 1.82 o.74 o.4714

LsSvert 80.7 3.94 78.2 5.60 2.O2 1.11 0.2800

LiSvert 72.1 4.66 73.2 6.42 1.9 0.38 0.7053

SiSvert 62.4 4.91 65.1 6.58 1.8 0.99 0.3335

STPSvert 63.0 4.64 65.0 8.38 3.26 0.58 0.5739 APPENDICES 249

Table 6l Gontrol comparison with the post-treatment male Clark Twin Block group

MALES CONTROL N=13 CTB N=17 Control vs CTB

Post Tx: MEAN SD MEAN SD F-ratio T value T prob

SNA 81.0 4.46 80.7 3.28 1.85 0.16 o.8717

ANB 7.5 1.47 4.6 2.10 2.04 4.30 0.0004

SNB 73.5 4.70 76.2 3.83 1.51 1.75 0.0869

Co-Gn 103.0 6.70 106.7 6.91 1.06 1.46 0.1 509

Ar-Gn 96.9 6.10 99.4 6.48 1.13 1.08 o.2884

UFH 50,3 4.80 49.1 2.79 2.96* o.82 0.4260

LFH 55.4 4.58 62.5 4.36 1.10 5.67 0.0000

N-Me 105.7 8.50 109.0 6.13 1.92 1.26 0.2175

A-Svert 64.2 4.41 65.6 3.51 '1.58 0.97 0.3426

B-Svert 50.7 7.59 56.9 5.92 1.64 2.51 0.0173

PogSvert 51.3 8.68 57.2 7.16 1.47 2.O4 0.0480

OJ 11.0 2.99 5.3 2.04 2.15 6.15 0.0000

OB 6.5 3.10 4.0 1.82 2.90* 2.60 0.0173

F.conv 130.3 6.23 128.6 4.35 2.05 0.89 0.387

N-Lang 123.4 9.18 127.4 7.98 1.32 1.26 o.2151

L-Mfold 1 16.3 17.14 126.3 10.40 2.72" 1.85 0.0764

Ls-A 16.4 2.04 20.3 2.31 1.28 4.91 0.0001

Li-B 20.4 3.46 22.2 2.53 1.87 1.67 0.1032

ST TFH 1 15.0 8.04 114.0 6.44 1.56 0.39 o.7012

ST UFH 55.2 4.78 48.4 3.34 2.05 4.60 0.0002

ST LFH 59.9 3.86 70.9 4.69 1.48 6.86 0.0000

STLFH% 52.1 1.42 62.1 1.75 1.52 16.94 0.0000

Ls-E 1.3 2.44 -0.5 2.01 1.47 2.23 0.0322

Li-E -0.4 2.92 0.0 2.57 1.29 0.40 0.6954

ULL 18.9 2.75 20.9 2.06 1.78 2.3 0.0273

LLL 38.5 3.11 47.O 2.15 2.09 8.94 0.0000

Sn-Svert 78.9 4.87 80.5 4.18 1.36 0.97 o.3434

SsSvert 77.6 5.01 79.4 4.65 1.16 1.00 0.3249

LsSvert 80.6 6.11 82.2 5.31 1.32 0.78 0.4503

LiSvert 71.1 6.27 77.0 5.27 1.42 2.79 0.0091

SiSvert 61.5 7.51 68.0 5.78 '1.69 2.69 0.0115

STPSvert 63.1 8.62 69.4 7.38 1.36 2.13 0.0394 APPENDICES 250

Table 62 Control comparison with the post-treatment female Glark Twin Block group

FEMALES CONTROL N=7 CTB N=1 3 Control vs CTB

Post Tx: MEAN SD MEAN SD F-ratio T value T prob

SNA 82.2 3.18 81.0 3.35 1.11 0.78 0.4531

ANB 7.O 3.13 4.8 2.38 1.73 52.43 0.0000

SNB 75.2 1.67 76.2 2.81 2.83 0.87 o4023

Co-Gn 99.1 5.20 101 .5 3.41 2.33 1.25 0.2254

Ar-Gn 91.7 4.70 95.3 3.92 1.44 1.81 0.0839

UFH 46.3 2.O4 47.4 1.53 1.78 1.48 0.1 535 ** LFH 53.1 7.05 59.8 3.19 4.88 2.41 0.0455 * N-Me 99.3 6.90 104.9 3.19 4.68 2.04 0.0791

A-Svert 63.5 4.71 64.1 3.72 1.60 o.28 0.7770

B-Svert 52.7 4.37 55.4 5.28 1.46 1.17 0.2580

PogSvert 53.4 4.58 55.5 5.89 1.65 0.82 0.4258

OJ 11.2 2.83 4.7 2.55 1.23 5.27 0.0001

OB 4.3 2.90 3.0 2.19 1.75 1.10 0.2870

F.conv 128.9 6.36 128.1 4.06 2.45 0.36 o.7244

N-Lang 123.7 7.82 129.2 8.96 1.31 1.38 0.1 804

L-Mfold 123.2 11.00 133.9 14.25 1.68 1.72 0.0987

Ls-A 17.2 1.13 18.9 1.59 1.98 2.47 0.0227

Li-B '19.5 3.06 20.6 2.81 1.19 0.81 0.4336 * ST TFH 107.7 6.51 109.7 3.70 3.10 0.75 o.4778

ST UFH 50.5 2.30 48.0 2.42 1.11 2.26 0.0347 * ST LFH 57.2 6.62 66.5 3.82 3.00 3.42 0.0091

STLFH% 53.0 3.28 60.6 2.44 1.81 5.91 0.0001

Ls-E 2.6 1.80 -1.5 2.51 1.94 3.79 0.0016

Li-E 0.8 3.07 -o.7 3.38 1.21 1.O2 0.3220

ULL 17.5 2.12 20.2 1.96 1.17 2.85 0.0104

LLL 37.0 3.26 44.2 2.81 1.35 5.20 0.0002

Sn-Svert 78.1 4.O2 77.9 3.43 1.37 0.11 0.9087

SsSvert 77.5 3.96 76.6 3.61 1.2 0.54 0.5995

LsSvert 80.7 3.94 78.7 4.36 1.22 1.05 0.3082

LiSvert 72.1 4.66 73.8 4.43 1.11 0.81 0.4343

SiSvert 62.4 4.91 66.1 4.04 1.48 1.85 o.o772

STPSvert 63.0 4.64 66.4 6.28 1.83 1.26 0.2202 AppeNorcss 25r

Table 63 Control comparison with the post-treatment male Fränkel group

MALES CONTROL N=13 FRÄNKEL N=15 Control vs Fränkel

Post Tx: MEAN SD MEAN SD F-ratio T value T prob

SNA 81.0 4.46 81.7 3.53 1.60 0.46 0.6513 * ANB 7.5 1.47 6.0 2.46 2.80 2.O1 0.0532 * SNB 73.5 4.70 75.7 2.68 3.08 1.50 0.1 468 * Co-Gn 103.0 6.70 104.1 3.94 2.89 0.51 o.6245

Ar-Gn 96.9 6.10 96.4 4.28 2.03 0.26 o.7897

UFH 50.3 4.80 48.4 2.59 3.43 " 1.23 0.2336

LFH 55.4 4.58 61.7 2.94 2.43 4.42 0.0003

N-Me 105.7 8.50 107.3 3.13 7.37 """ 0.63 0.5444

A-Svert 64.2 4.41 66.2 4.24 1.08 1.22 0.2333

B-Svert 50.7 7.59 55.8 5.23 2.11 2.10 0.0434

PogSvert 51.3 8.68 56.0 6.23 1.94 1.66 0.1056

OJ 11.0 2.99 5.7 2.02 2.19 5.48 0.0001

OB 6.5 3.10 4.6 2.16 2.06 1.89 0.0665 * F.conv 130.3 6.23 127.5 3.68 2.87 1.41 0.1704

N-Lang 123.4 9.18 131 .0 7.42 1.53 2.43 o.0212

L-Mfold I 16.3 17.14 '130.9 11.09 2.39 2.70 0.01 15

Ls-A 16.4 2.04 19.8 1.35 2.28 5.38 0.0001

Li-B 20.4 3.46 22.4 2.58 1.80 1.81 0.0786 ** ST TFH 1 15.0 8.04 111.8 3.75 4.60 1.33 0.2004 ** ST UFH 55.2 4.78 48.5 1.88 6.46 4.77 0.0004

ST LFH 59.9 3.86 68.8 3.30 1.37 6.61 0.0000

STLFH% 52.1 1.42 61.5 1.79 11.59 15.32 0.0000

Ls-E 1.3 2.44 0.2 1.86 1.72 1.35 0.1 852

Li.E -o.4 2.92 0.1 1.92 2.31 0.52 0.6129

ULL 18.9 2.75 21.2 1.36 4.09 "* 2.74 0.0134

LLL 38.5 3.11 45.6 2.51 1.54 6.74 0.0000

Sn-Svert 78.9 4.87 80.7 4.O4 1.45 1.06 0.2978

SsSvert 77.6 5.01 79.2 4.O7 1.52 0.90 0.3780

LsSvert 80.6 6.11 8'1.8 4.12 2.2Q 0.63 0.s395

LiSvert 71 .1 6.27 75.9 4.10 2.34 2.42 0.0214 * SiSvert 61.5 7.51 67.1 4.67 2.59 2.33 0.0287

STPSvert 63.1 8.62 67.5 6.22 1.92 1.57 0.1 239 APPENDICES 252

Table 64 Control comparison with the post-treatment female Fränkel group

FEMALES CONTROL N=7 FRÄNKEL N=14 Control vs Fränkel

Post Tx: MEAN SD MEAN SD F-ratio Tvalue Tprob

SNA 82.2 3.18 80.5 2.45 1.68 '1.30 0.2086 ** ANB 7.0 3.13 5.5 1.43 4.79 1.17 o.2786

SNB 75.2 1.67 75.0 2.74 2.69 0.16 0.8701

Co-Gn 99.1 5.20 100.7 5.32 1.05 0.67 0.5195

Ar-Gn 91.7 4.70 94.1 5.96 1.61 0.92 0.3725

UFH 46.3 2.04 48.3 2.44 1.43 1.95 0.0638 ** LFH 53.1 7.05 58.8 2.96 5.67 2.07 0.0751

N-Me 99.3 6.90 104.8 4.24 2.65 2.26 0.0336

A-Sveft 63.5 4.71 62.7 4.15 1.29 0.40 0.6963

B-Svert 52.7 4.37 52.5 5.60 1.64 0.07 0.9433

PogSvert 53.4 4.58 52.1 6.04 1.74 0.49 0.6333

OJ 11.2 2.83 4.1 1.15 6.06 6.38 0.0007

OB 4.3 2.90 3.6 2.00 2.10 o.67 0.5175 * F.conv 128.9 6.36 127.7 3.22 3.90 0.47 o.6512

N-Lang 123.7 7.82 129.5 7.77 1.01 1.64 o.1148 * L-Mfold 123.2 11.00 134.4 6.19 3.16 2.51 0.0350

Ls-A 17.2 1.13 18.5 1.27 1.26 2.20 0.0383

Li-B 19.5 3.06 22.6 1.38 4.92** 2.60 o.0342

ST TFH 107.7 6.51 108.0 6.40 1.03 0.11 0.9092

ST UFH 50.5 2.30 46.9 4.12 3.21 2.13 0.0438

ST LFH 57.2 6.62 66.3 4.34 2.33 3.80 0.0015

STLFH% 53.0 3.28 61.4 2.26 2.11 6.93 0.0000

Ls-E 2.6 1.80 -0.5 1.72 1.10 3.84 0.0014

LI-E 0.8 3.07 0.4 2.14 2.06 0.38 0.7059

ULL 17.5 2.12 19.9 1.99 1.13 5.82 0.0001

LLL 37.0 3.26 44.8 4.14 1.61 4.35 0.0006

Sn-Svert 78.1 4.02 76.6 4.64 1.33 o.75 0.4675

SsSvert 77.5 3.96 75.0 4.70 1.41 1.20 o.2433

LsSvert 80.7 3.94 77.2 5.80 2.17 1.44 0.1 646

LiSvert 72.1 4.66 72.5 5.54 1.41 0.14 0.8824

SiSvert 62.4 4.91 63.8 5.77 1.38 0.58 0.5776

STPSvert 63.0 4.64 63.8 6.29 1.84 0.30 o.7614 AppBNrrcss 253

Comparison of changes in the activqtor treatment and Lange et al. (1995) control groups.

Males and females are combined in this control group.

Table 65 Lange et al. control comparison with the post-treatment activator group

Post Tx: Controls N=30 Activator N=35 Control vs Act

TOTAL MEAN SD MEAN SD F-ratio Tvalue Tprob. ** AGE 10.5 1.08 11.1 1.7 2.48 1.72 0.0867 *"* Tx TIME 557 149 610 308 4.27 0.90 o.3745 *" * SNA o.4 0.7 -o.23 1.3 3.24 2.54 0.0135 *"* *** ANB -0.11 0.6 -1.46 1.1 3.61 6.09 0.0000

IMPA -o.23 3.2 -1.46 3.3 1.09 1.51 0.1325 ** ** SNB 0.53 0.7 1.24 1.1 2.70 3.05 0.0037 *** *** Ar-Gn 2.83 1.7 5.28 3.1 3.45 3.98 0.0004 ** Ar-Go 1.53 1.4 2.99 2.7 3.66 "** 2.81 0.0070 * UFH 1.57 1.2 1.62 1.8 2.33 0.13 0.8908 * ** LFH 1.35 1.8 2.94 2.5 1.93 2.97 0.0045 ** N-Me 2.98 1.9 5.00 3.0 2.49 "* 3.30 0.0020

FMA -0.22 1.1 0.08 1.9 2.92*" 0.80 0.4339 * N-Lang -o.12 7.2 4.O2 9.3 1.67 1.98 0.0491 *** L-Mfold -2.2 2.4 12.88 12.0 25.17 "** 7.24 0.0000

Li-E -0.6 1.5 -1.34 2.3 2.29* 1.57 o.1179 ** ULL 0.33 1.0 0.80 1.7 2.82 1.39 0.1 659 *** *** OJ 0.12 0.8 -4.24 2.1 6.96 11.31 0.0000 **i OB o.7 1.1 -1.92 1.7 2.3* 7.56 0.0000

(*) signifrcant at p<0.05

(* *) significant at p<0.01

(r< * *) significant at p<0.001 AppeNplcns 254

Controls N=30 Activator N=35 Control vs Act landmark MEAN SD MEAN SD F-ratio Tvalue Tprob *** A x-axis 1.98 1.1 0.28 1.3 1.40 5.64 0.0000 *** y-axrs -1.47 1.3 -2.32 2.9 4.81 1.58 0.1 I 61 * Bx 2.00 1.2 1.72 1.7 2.08 o.77 0.4527 *** **i v -2.43 '1.8 -4.82 3.4 3.61 3.59 0.0010 *** U1E x 2.17 1.6 -2.54 2.1 1.67 10.13 0.0000 *** v -1.85 1.3 -2.53 2.6 4.'l 6 1.34 0.1 826 L1E x 2.17 1.4 1.69 1.7 1.54 1.21 0.2282 *** *+* v -1.47 1.4 -4.45 2.7 3.80 5.65 0.0000 **', Pog x 2.20 1.1 1.53 2.0 3.41 1.69 0.0939 *** *** v -2.68 1.6 -6.12 3.8 5.79 4.82 0.0001 *** Snx 2.60 1.4 1.19 1.7 1.49 3.6 0.0009 * v -1.83 1.7 -2.76 2.6 2.30 1.74 0.0838 *** Ssx 2.73 1.5 0.13 2.O 1.72 5.91 0.0000 *** * v -2.03 1.4 -3.23 3.2 5.29 2 0.0488 *** Lsx 2.53 1.5 -0.42 2.5 2.82*" 5.83 0.0000 *"* ** v -2.01 1.5 -3.68 3.2 4.61 2.74 0.0084 **+ Ll x 2.82 1.4 1.58 2.7 2.04 " 10.38 0.0000 *"* v -1.58 2.0 -2.61 4.1 4.1 I 1.32 0.1907 Si x 2.58 1.5 3.04 2.3 2.39 "* 0.96 0.3419 *** * v -1.67 2.0 -3.63 4.3 4.58 2.42 0.0182

ST Pog x 2.80 1.2 2.19 2.6 4.52*** 1.26 0.2105 *** ** v -2.47 2.1 -5.41 4.5 4.63 3.44 0.0015

Backward and downward movements of the landmark, as determined with cranial base superimposition are denoted by a minus sign (-).

(*) significant at p<0.05

(* *) signihcant at p<0.01

(*:r' *) significant at p<0.001 APPENDICES 255

Comparison of changes in the Clark Twin Block treatment and Lange et al (1995) control groups.

Males and females are combined in this control group, thus males annd females combined in the current treatment group.

Table 66 Lange et al. control comparison with the current post-treatment Glark Twin Block study

Post Tx: Gontrols N=30 CTB N=30 Control vs CTB

TOTAL MEAN SD MEAN SD F-ratio Tvalue Tprob.

AGE 10.5 1.1 10.6 1.4 1.68 0.31 0.7559 * Tx TIME 557 149 465 144 1.07 2.43 0.0172 *** SNA 0.4 o.7 -0.48 1.1 2.51 '," 3.67 0.0009 *** ANB -0.11 0.6 -1.87 1.4 5.44 ""* 6.33 0.0000 ** IMPA -0.23 3.2 3.17 5.0 2.43* 3.14 0.0032 *** ** SNB 0.53 0.7 1.39 1.3 3.66 3.12 0.0035 * ** Ar-Gn 2.83 1.7 4.68 2.3 1.88 3.51 0.0013 ** *+ Ar-Go 1.53 1.4 2.88 2.3 2.68 2.75 0.0082

UFH 1.57 1.2 1.47 1.4 11.4 0.29 o.7667

+ LFH 1.35 1.8 2.42 1.4 1.61 2.56 0.0127 ** N-Me 2.98 1.9 4.30 1.9 1.03 2.71 0.0086

FMA -o.22 1.1 0.33 1.7 2.28" 1.51 0.1329 * N-Lang -o.12 7.2 4.03 6.3 1.29 2.37 0.0200 *** L-Mfold -2.2 2.4 14.11 9.4 15.24 """ 9.24 0.0000

Li-E -0.6 1.5 -0.20 1.2 1.49 1.13 0.2624

ULL 0.33 1.0 0.65 1.5 2.13 " 0.99 0.3277 *** *** OJ o.12 0.8 -5.16 2.7 11.14 10.38 0.0000 ** *** OB o.7 1.1 -2.15 2.O 3.24 6.89 0.0000

(*) significant at p<0.05

(* *) significant at p<0.01

(* **) significant at p<0.001 APPENDICES 256

Controls N=30 CTB N=30 Control vs CTB landmark MEAN SD MEAN SD F-ratio Tvalue Tprob *** A x-axis 1.98 1.1 o.42 1.7 2.36" 4.24 0.0003

y-axis -1.47 1.3 -1.65 1.7 1.75 0.46 0.6538

Bx 2.O0 1.2 2.42 2.7 5.1 0 "** 0.78 0.4483 * *** v -2.43 1.8 -4.91 2.8 2.39 4.10 0.0003 ** *** U1E x 2.17 1.6 -1.54 2.6 2.56 6.73 0.0000 * v -1.85 1.3 -2.68 1.8 1.92* 2.05 0.0430 ** L1E x 2.17 1.4 3.62 2.2 2.51 "" 3.03 0.0042 *** v -1.47 1.4 -4.83 2.1 2.21 " 7.34 0.0000 **" Pog x 2.20 1.1 2.39 2.6 5.76 0.36 o.7185 *** v -2.68 1.6 -4.65 1.8 1.21 4.54 0.0001 ** Snx 2.60 1.4 1.08 2.1 2.19 " 3.33 0.0020

v -1.83 1.7 -1.75 1.8 1.12 0.18 0.8544 * *** Ssx 2.73 '1.5 0.52 2.1 2.04 4.63 0.0001 ** v -2.03 1.4 -2.74 2.5 3.29 1.34 0.1837 *" *** Lsx 2.53 1.5 -0.11 2.5 2.78 4.96 0.0001 * v -2.01 1.5 -2.19 2.1 1.89 0.39 0.7022 *** Li x 2.82 1.4 3.06 3.2 5.1 6 0.38 0.7085

v -1.58 2.0 -1.34 2.4 1.50 o.42 0.6823 **" * Si x 2.58 1.5 4.18 3.1 4.30 2.54 0.0143 * v -1.67 2.0 -2.48 2.8 1.95 1.29 0.1 991 *"* ST Pog x 2.80 1.2 3.18 3,3 7.38 0.60 0.5595 ** v -2.47 2.1 -3.26 3.5 2.70 1.07 0.2894

Backward and downward movements of the landmark, as determined with cranial base superimposition are denoted by a minus sign (-).

(*) significant at p<0.05

(**) signihcant at p<0.01

(* {. *) significant at p<0.001 APPENDICES 257

Comparison of changes in the Frrinkel treatment and Lange et al. (1995) control groups.

Males and females are combined in this control group.

Table 67 Lange et al. control comparison with the post-treatment Fränkel group

Post Tx: Controls N=30 Fränkel N=29 Gontrol vs Fr

TOTAL MEAN SD MEAN SD F-ratio Tvalue Tprob.

AGE 10.5 1.1 10.8 1.3 1.45 0.97 0.3400 ** Tx TIME 557 149 596 257 2.98 0.72 0.4825 *"" ** SNA o.4 o.7 -0.43 1.5 4.41 2.75 0.0087 *" *** ANB -0.11 0.6 -1.15 1.0 2.61 4.93 0.0001 ** IMPA -o.23 3.2 2.O7 5.5 2.93 1.96 0.0532 ** SNB 0.53 o.7 o.72 1.3 3.29 0.71 0.4894 ** +i Ar-Gn 2.83 1.7 4.78 2.7 2.50 3.32 0.0021 ** Ar-Go 1.53 1.4 2.97 2.0 2.12* 3.15 0.0031 * UFH 1.57 1.2 2.21 1.7 1.98 1.67 0.0969 ** LFH 1.35 1.8 3.25 2.3 '1.66 3.52 0.0012 *** N-Me 2.98 1.9 5.60 2.6 1.92" 4.37 0.0002 ** FMA -0.22 1.1 0.24 1.9 3.11 1.12 0.2701 * N-Lang -o.12 7.2 3.90 6.8 1.12 2.2 0.0299 *** L-Mfold -2.2 2.4 15.83 11.4 22.76 ""* 8.31 0.0000

Li-E -0.6 1.5 -1.33 1.4 1.13 1.92 0.0562 *** ULL 0.33 1.0 0.75 2.3 5.11 0.92 0.3675 i** OJ 0.12 0.8 -4.49 1.8 4.48 "*" 12.88 0.0000 *" *** OB o.7 1.1 -2.71 1.8 2.68 8.74 0.0000

(*) significant at p<0.05

(* *) significant at p<0.01 *) (* 'r'! significant at p<0.001 AppBNotcss 258

Gontrols N=30 Fränkel N=29 Gontrol vs Fränkel landmark MEAN SD MEAN SD F-ratio Tvalue Tprob. *** A x-axis 1.98 1.1 0.64 1.5 1.91 " 3.87 0.0006 ** y-axrs -1.47 1.3 -2.41 2.2 2.94 1.97 0.0522 *" Bx 2.00 1.2 1.68 2.1 3.12 0.71 0.4881 *** v -2.43 1.8 -5.27 2.2 1.52 5.41 0.0000 *** U1E x 2.17 1.6 -1.84 2.1 1.66 8.37 0.0000 * v -1.85 1.3 -2.72 1.9 2.09* 2.06 0.0420 L1E x 2.17 1.4 2.66 2.1 2.23" 1.05 0.2972 *** v -1.47 1.4 -5.43 2.1 2.25" 8.49 0.0000 *"* Pog x 2.20 1.1 1.46 2.3 4.56 1.54 o.1278 * *** v -2.68 1.6 -5.44 2.3 2.09 5.32 0.0000 * Snx 2.60 1.4 1.16 2.6 3.45 ""* 2.64 o.0112

v -1.83 1.7 -2.50 2.O 1.41 1.38 0.1 696 *** Ssx 2.73 1.5 0.58 2.4 2.52',* 4.14 0.0003 *** * v -2.03 1.4 -3.47 3.0 4.5 2.37 0.0215 *** Lsx 2.53 1.5 -0.07 2.5 2.76 "" 4.84 0.0001 * * v -2.01 1.5 -2.97 2.1 1.98 2.O1 0.0473 Li x 2.82 1.4 1.81 2.9 4.20 ""* 1.71 0.0916

v -1.58 2.0 -2.29 2.2 1.19 1.3 0.1 945

S¡ X 2.58 1.5 3.43 2.1 2.O2* 1.77 0.0797 * *** v -1.67 2.0 -4.08 2.9 2.15 3.68 0.0009 *** ST Pog x 2.80 1.2 2.66 3.1 6.63 0.23 o.8157 * ** v -2.47 2.1 -4.78 2.9 't .91 3.49 0.0013 Backward and downward movements of the landmark, as determined with cranial base superimposition are denoted by a minus sign (-).

(*) significant at p<0.05

(**) significant at p<0.01

(***) significant at p<0.001

8.7 INDIVIDUAL TREATMENT CHANGES FOR SELECTED VARIABLES

Figure 27 Graphs displaying the individual changes, for selected var¡ables observed in the three functiona appliance groups. AppsNolcss 259

SNA Ghanges- Male

SNA ChEngs (Malæ)- ACT

hgda

-1

-1

I 2 3 4 5 6 7 A 9 10 11 12 13 14 15 16 17

SNA Changes (Malos) - CTB

&gñ!

1 2 3 4 5 6 7 A S 10 11 12 13',14 15 16

SNA Changes (Mal€s) - FR

hgæ! -'l AppBNorcss 260

SNA Changes- Female

SNA Chsngos (Femalss)- ACT

ùgÉa

-1

-2

1 2 3 4 5 I 7 6 I 10 11 12 13 14 15 16 17 1A

SNA Changes (Femalos) - CTB

-05 hgße3 -l

1234567AS1011121314

SNA Changos (F€mals8) - FR

05

&gße! 0

-1

1234567A91011121314 APPENDICES 261

SNB Ghanges- Male

SNB Chsngos (Male8)- ACT

heEs 1 Fs'j""n

-l 1 2 3 4 5 6 7 A I 10 11 12 13 14 15 16 17

SNB Chsnges (Male8) - CTB

hgE!

-1

SNB Changos (Males) - FR

hgæt

-1 AppBNorcss 262

SNB Changes- Female

SNB Ch¡ngo. (Fomalos)-ACT

15

25

15

0ã

{5

SNB Changæ (Female8) - CTB

&gE€6

-1

SNB Changss (Fenalos) - FR

l5

05 fug@s

-05

-1

1234567A91011121314 AppBNnrcBs 263

ANB Ghanges- Male

ANB ChmgoB (MalE)-ACT

{5

-1

lE"*¡

-25

i5

t0 11 12 13 16 17

ANB Chang€s (Mslos) - CTB

&gæs i

-3

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 18

ANB Changos (Malôs) - FR

-1

-1 &gü!

1 2 3 4 5 6 7 ø I 10 11 12 13 14 15 AppBNlrcss 264

ANB Ghanges- Female

ANB ChangoB (Fomålos).ACT

05

I

,2

-35

10 11 12 t3 11 17 16

ANB Changos (Fon8l€s) - CTB

o5

-1

&O@3

1234567A91011121314

ANB Chang€s (F€males) - FR

t5

-1

34567A91011121314 AppeNorcBs 26s

Mandibular Length (Co-Gn) Ghanges- Male

Mandlbuler L€nglh Changos (Males)-ACT

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 16 17

Mandlbular Length Changss (Malos) - CTB

12

mm

1 2 3 4 5 ô 7 8 9 10 11 12 13 14 15 16

Mandlbulsr Length Chang€s (Meles) - FR

10

1 2 3 4 5 6 7 A I l0 11 12 13 14 15 APPENDICES 266

Mandibular Length (Co-Gn) Ghanges- Female

Mandlbular Longth Changes (Femalos)- ACT

1 2 3 4 s 6 7 A I l0 11 12 13 14 15 16 17 1ø

Mandlbular Length Chsnges (Females) - CTB

1234567891011121314

Mandlbqlar Length Changos (Females) - FR

12 34567A91011121314 AppBNoICBS 267

U1-SN Ghanges- Male

Ul-SN Changes (Malo8) - ACT

hgÉa Fa",ñl

1 2 3 4 5 6 7 A I l0 11 12 13 14 15 16 17

Ul-SN Changê8 (Male8) - CTB

hgÈB

1 2 3 4 5 6 7 A S l0 11 12 13 14 15 16

Ul-SN Chsnges (Males) - FR

&gÉB

1 2 3 4 5 6 7 I S l0 11 12 13 14 15 AppeNnrcps 268

Ul-SN Changes- Female

ul.SN Chqnges lFemsles) - ACT

hgm. Es-dl

1 2 3 4 5 6 7 E I 10 11 12 13 14 15 16 17 1A

UI.SN Change8 (Femalæ) - CTB

6 &g@6

U1-SN Chenge8 (Femsle8) - FR

&gÉ! AppeNorcBs 269

IMPA Changes- Male

IMPA Changes (Males) - ACT

1 2 3 4 5 6 7 A I 10 11 12 13 14 l5 16 17

IMPA Changes (M8los) - CTB

hgßss

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 16

IMPA Changes (M8les) - FR

frgæl

1 2 3 4 5 6 7 ø I 10 11 12 13 14 15 AppsNnlces 270

IMPA Ghanges- Female

IMPA Changes (Femalss)- ACT

&gEs LJ

3 6 11 12 14 16 17 18

IMPA Changss (Females) - CTB

&gÞes

-4 10 11 12 13 14

IMPA Changes (Females) - FR

æOËs

-a

l0 12 t3 t4 ApppNnlcss 27r

FMA Ghanges- Male

FMA Changes (Mal€s) - ACT

hgË! FsÃìl I

-2

-3

3 I 11 12 13 14 17

FMA Chang€s (Malesl. CTB

&gm3

-1

FMA Chang€s (Malos) . FR

15

05 frgm6 0

-05

-1

-1 5

-2

1 2 3 4 5 6 7 ø I 10 11 12 13 14',15 AppeNorcBs 272

FMA Ghanges- Female

FMA Chsnges (Fomales) - ACT

hgÉaB

-2

FMA Changês (Femalæ) - CTB

ægEêE

I

-1 5

FMA Changos (Femal€sl - FR

hgfts

1234567A91011121314 AppBNrrcss 273

Facial Convexity Changes- Male

F.Convexlty Chsngos (Malos) - ACT

hgE€s

-10

F. convoxlty Changos (Malo8) - cTB

ftg@s

-1

-2

F. Conv€xlty Changes (Males) - FR

h0Hl ApppNorces 214

Facial Convexity Changes- Female

F, Convexity Changes (F€m8les) - ACT

&gP€3

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 16 17 1ø

F. Convêx|ty Changes (Fomales) - CTB

ftg@s

-1

1234567891011121314

F.Convexity Chang€s (Females) - FR

hgæs lsedês1

-1

1234567A91011121314 AppsNorcss 275

Nasolabial Angle Ghanges- Male

Nasolablal Angle Changes (Males) - ACT

&gÞoB I

1 2 3 4 5 6 7 S I 10 11 12 13 14 15 16 17

NaEolablal Angle Changss (Males) - CTB

&gEes

-2

-4

Naslolablal Angle Change8 (Males) - FR

10

D€gñ6 6

4

2

1 2 3 4 s 6 7 A I lO 11 12 13 14 15 AppeNrrcss 276

Nasolabial Angle Ghanges- Female

Naeolsblal Anglo Changes (Females) - ACT

&gßeg

3 11 12 13 14 15 16 17 1E

NaBolablal Angle Changes (Fomales) . CTB

-10 10 11 12 13 14

Nasolablal Angle Chsnges (Females). FR

ægÈs

1234567ø91011121314 AppBNtrces 277

Labiomental Fold Ghanges- Male

Lab¡omenlal Fold Changes (Msl€s) . ACT

&0Ër

1 2 3 4 5 6 7 A 9 10 11 12 13 14 15 16 17

Lablomental Fold Change6 (Males) . CTB

fÞg@s

1 2 3 4 5 6 7 I S 10 11 12 13 14 15 16

Lablomental Fold Chang€s (Males) - FR

hgmB AppsNlIcBs 278

Labiomental Fold Changes- Female

Lablomental Fold Chsnges (Females) . ACT

hgßea

-1 1 2 3 4 5 6 7 A 9 t0 11 12 13 14 15 t6 17 1A

Lablomental Fold Changes (Femalos) - CTB

25

&gÈ3

15

10

Lsbiomental Fold Changes (FemaleB) . FR

ÞOË¡

1234567891011121314 AppBNnIcBs 279

Sulcus Superius to Sella vertical Ghanges- Male

Ss.Svertlcal Changss (MaleB)- ACT

ñm1 Fil;I

-1

4 6 I 10 11 12 14 16 17

Ss.Svertlcal Changês (Male8) - CTB

-1

1 2 3 4 5 6 7 A I 10 11 12 13 14 l5 16

Ss-Svertlcal Changos (Males) . FR

-1

-2 AppBNrlcBs 280

Sulcus Superius to Sella vertical Ghanges- Female

Ss€vertical Chang6s (F€mal€s) - ACT

1 2 3 4 5 6 7 A 9 10 11 12 13 14 15 16 17 1ø

Ss€vertlcal Changes (Females) - CTB

lo 11 12 13 14

Ss-Svertical Changss (F€males)- FR

-1

-2

-4

I 9 10 11 12 14 AppsNnrcps 281

Labrale Superius to Sella vertical Changes- Male

Ls€vert¡cal Changes (Malos) - ACT

mm E"*".1 -2

-4

1 2 3 4 s 6 7 A I 10 11 12 13 14 15 16 17

Lssvert¡cal Changes (Males) - CTB

-1

1 2 3 4 5 6 7 A 9 10 11 12 13 14 15 16

Ls.Svertlcal ChangEs (Mal€s) - FR

lsedesl

-1

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 AppE,N¡Icps 282

Labrale Superius to Sella vertical Ghanges- Female

Ls-Sv€rtlcal Changes (Femalê3) - ACT

ffi,_ fl U' Lü Bgês L$ fäè"¡å"iì -1

1 2 3 4 5 6 7 I I 10 11 12 13 14 15 16 17 1A

Lssvertlcal Changes (Fsmales) - CTB

-l

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Ls.Svertical Changes (Fomal€s) - FR

7ø91011121314 AppBNorces 283

Labrale lnferius to Sella vertical Changes- Male

Llsvorllcal Changes (Mal€s) - ACT

-3

3 10 1'l 12 14 15 17

Ll.Svert¡cal Changes (Malss) -CTB

mm

-t 1 2 3 4 5 6 7 ø I 10 11 12 13 14 15 16

Ll.Svertlcal Changos (Males) - FR

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 AppsNnrc¡s 284

Labrale lnferius to Sella vertical Changes- Female

Ll.Svertlcal Chqngos (Fomales) . ACT

lo

1t 12 13 14 l5 17 18

Ll.Svertlcal Changss (Fsmales) - CTB

1234567A91011121314

Ll-Sverlical Changes (Femal€s) . FR

mm2 ¡s€d6s1

1

-1

567891011121314 AppBNoICBS 28s

Soft Tissue Pogonion to Sella vertical Ghanges- Male

ST Pog-Svortlcal (Males) - ACT

-1

1 2 3 4 5 6 7 ø 9 10 11 12 13 14 15 16 17

ST Pog.Svertlcal Changes (Mal€s) - CTB

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 16

sT Pog.Svertlcal changes (Males) - FR AppBNrrcss 286

Soft Tissue Pogonion to Sella vertical Changes- Female

ST Pog.Svsrtlcal (Fomale8) . ACT

ST Pog.Svert¡cal ChangeE (Females) - CTB

ññ2

1234567491011121314

ST Pog-Svertlcal Changes (Femalss) - FR

-

567491011121314 AppBN¡IcBs 287

Overjet Changes- Male

oJ Changes (MalosÞACT

-1

mm

1 2 3 4 5 6 7 A I l0 11 12 13 14',15 16 17

OJ Changes (Males) - CTB

mm

1 2 3 4 5 6 7 ø I 10 11 12 13 14 15 16

OJ Chsnges (Males) - FR

-1

-6

-7

-8

1 2 3 4 5 6 7 A 9 10 11 12 13 14 15 AppBN¡IcsS 288

Overiet Changes- Female

OJ Chang€s (FemsloE) - ACT

n

-2

1 2 3 4 5 6 7 A I 10 11 12 13 14 15 18 17 1A

OJ Changos (Females) - CTB

-1

-7

1234567A91011121314

OJ Changes (Fsmale8) - FR

-1

mm

1234567ø91011121314