ISSN: 1812–1217

Comparison Among Three Fixed Palatal

Expander Appliances: An in Vitro Study

Hussian A Al-Obaid Depart. of Pedod, Orthod, and Prev BDS, MSc (Prof.) College of Dentistry, University of Mosul

Mahmoud R Al-Mallah Depart. of Pedod, Orthod, and Prev Dentistry BDS College of Dentistry, University of Mosul

اﻟﺨﻼﺻﺔ اﻷﻫﺪاف ﻬﺗﺪف اﻟﺪراﺳﺔ إﱃ ﺗﻘﻴﻴﻢ ﺛﻼث ﻣﻮﺳﻌﺎت ﻟﻠﻔﻚ اﻟﻌﻠﻮي (ﺣﻨﻜﻴﺔ) ﻋﻠﻰ اﻟﺘﻐﲑات اﻟﻌﺮﺿﻴﺔ ﺑﲔ اﻟﻀﻮاﺣﻚ اﻷوﱃ واﻟﻀﻮاﺣﻚ اﻟﺜﺎﻧﻴﺔ واﻟﺮﺣﻰ اﻷوﱃ اﻟﻌﻠﻮﻳﺔ. اﻟﻤﻮاد وﻃﺮاﺋﻖ اﻟﻌﻤﻞ: ﻗﺴﻤﺖ اﻟﻌﻴﻨﺔ إﱃ ﺛﻼث ﳎﺎﻣﻴﻊ. ﻣﻮﺳﻊ اﳍﺎﻳﺮﻛﺲ وﻣﻮﺳﻊ رﺑﺎﻋﻲ اﳊﻠﺰون وﻣﻮﺳﻊ دﺑﻠﻴﻮ اﻟﻘﻮﺳﻲ. أﺧﺬت ﺻﻮر ﻗﺒﻞ وﺑﻌﺪ ﻋﻤﻠﻴﺔ اﻟﺘﻮﺳﻊ وﰎ أﺧﺬ اﻟﻘﻴﺎﺳﺎت ﺑﺎﺳﺘﺨﺪام ﺑﺮﻧﺎﻣﺞ أوﺗﻮﻛﺎد واﺳﺘﺨﺪم إﺧﺘﺒﺎري اﻷﻧﻮﻓﺎ ودﻧﻜﻦ ﻟﺘﺤﻠﻴﻞ اﻟﺒﻴﺎﻧﺎت. اﻟﻨﺘﺎﺋﺞ: ﺑﻴﻨﺖ اﻟﻨﺘﺎﺋﺞ أن ﻣﻌﺪل اﻟﺘﻐﲑات اﻟﻌﺮﺿﻴﺔ ﺑﲔ اﻟﻀﻮاﺣﻚ اﻷوﱃ واﻟﻀﻮاﺣﻚ اﻟﺜﺎﻧﻴﺔ واﻟﺮﺣﻰ اﻷوﱃ اﻟﻌﻠﻮﻳﺔ أﻇﻬﺮت ﻓﺮﻗﺎ ﻣﻌﻨﻮﻳﺎ ﺑﲔ ﻣﻮﺳﻊ اﳍﺎﻳﺮﻛﺲ وﺑﻘﻴﺔ اﳌﻮﺳﻌﺎت اﳊﻨﻜﻴﺔ ﺑﻴﻨﻤﺎ ﱂ ﻳﻮﺟﺪ ﻓﺮﻗﺎ ﻣﻌﻨﻮﻳﺎ ﺑﲔ ﻣﻮﺳﻊ رﺑﺎﻋﻲ اﳊﻠﺰون وﻣﻮﺳﻊ دﺑﻠﻴﻮ اﻟﻘﻮﺳﻲ. اﻹﺳﺘﻨﺘﺎﺟﺎت: ﻣﻮﺳﻊ اﳍﺎﻳﺮﻛﺲ أدى إﱃ ﺗﻮﺳﻊ أﻛﱪ ﰲ اﻟﻘﻮس اﻟﻔﻜﻲ اﻟﻌﻠﻮي ﻣﻦ ﺑﻘﻴﺔ اﳌﻮﺳﻌﺎت.

ABSTRACT Aims: To evaluate the effect of three different palatal expanders (Hyrax, Quad-Helix and W-Arch) on maxillary 1st premolar, 2nd premolar and 1st molar width changes. Materials and Methods: The sample consisted of three groups, the Hyrax (N=10), the Quad-Helix (N=10) and the W-Arch (N=10). Images were taken before and after expansion; analysis were made using Autodesk AutoCAD© pro- gram. One-way ANOVA and Duncan's multiple range tests were used (P ≤ 0.05). Results: Significant difference was found in the maxillary 1st premolar, 2nd premolar and 1st molar width changes between the Hyrax and the other two expanders, while there was no significant difference between the Quad- Helix and the W-Arch expanders. Conclusion: Maxillary arch width increases more consistently with the Hyrax expanders. Keywords: Palatal expander, Hyrax, Quad-Helix, W-Arch.

Al-Obaidi HA, Al-Mallah MR. Comparison among Three Fixed Palatal Expander Appliances: An in Vitro Study. Al–Rafidain Dent J. 2014; 14(1): 37-46. Received: 3/9/2012 Sent to Referees: 4/9/2012 Accepted for Publication: 6/11/2012

(5) INTRODUCTION pand the maxillary arch. P P Increased max- A common feature seen in orthodontic illary arch width has been related to ortho- patients is a narrow or constricted maxil- dontic movements, orthopedic movements, (1) lary arch P ,P in which the maxillary width or a combination of these movements dur- (6) is narrower than the norm for a particular ing expansion procedures. P P Skeletal ex- (2) age group. P P The origin of a constricted pansion involves separating the maxillary maxilla can be skeletal, dental, or combi- halves at the midpalatal suture, while den- (3) nation of both structures. P tal expansion results from buccal tipping (7) Diagnosis of transverse skeletal dis- P ,P or bodily movement of the maxillary (8) crepancy is difficult. There are various posterior teeth. P methods used to diagnose this condition. Expansion of the palate was first Clinical evaluation, model analysis, occlu- achieved by Emerson C. Angell in 1860 sograms, and radiographic measurements and has been one of the oldest means of (9) have been recommended for an accurate creating space in the dental arches P ,P to (4) assessment. P correct crossbites or expand arch perime- (10) The correction of transverse maxillary ters to alleviate dental crowding. P P One deficiency can be an important component of the benefits of maxillary expansion is to (11) of an orthodontic treatment plan. A num- minimize the need to extract teeth. P ber of orthodontic techniques exist to ex- Several orthodontic techniques and

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expanders are available to expand the panders (Hyrax, Quad-Helix and W-Arch) maxillary arch. Rapid maxillary expansion on maxillary 1st premolar, 2nd premolar (RME), slow maxillary expansion (SME) and 1st molar width changes. (9), semi rapid maxillary expansion (12) (SRME) and surgically assisted rapid MATERIALES AND METHODS (SARPE) can be used The sample composed of 3 groups. (13). Palatal expanders can be removable or The first group consisted of Hyrax screw expanders, the second group consisted of fixed, banded or bonded, tooth-borne or (14) Quad-Helix appliances and the third group tooth and tissue-borne. was W-Arch appliances (Figure 1). The purpose of this study is to evaluate the effect of three different palatal ex-

Figure (1): From above to bottom: Hyrax screw, Quad-Helix and W-Arch d A. Preparation of Typodont screw to the metal base of typodont. A maxillary typodont wax form and After construction of immobilization metallic teeth were prepared according to plate, an impression was taken using rub- manufacturer's instructions (Ormco, Ja- ber base impression material (heavy and pan) to be used in this study by removing light body) and poured with dental stone. the top and bottom metal plate and insert- The cast was used to construct the acrylic ing the wax forms and then replacing the bite plane. This bite plane was used for metal plates followed by inserting the repositioning premolars and first molars to teeth into the wax forms and pressing the their original position after each trial. teeth firmly into the wax. B. Fabrication of Palatal Expanders Using rubber base impression material An impression was taken using algi- (heavy and light body) (Spofadent, Ger- nate impression material (Major, Italy) many), an impression was taken for typo- with preformed bands (Dentaurum, Ger- dont; followed by pouring the impression many) were fitted on 1st premolars and 1st with dental stone (Zhermack, Italy). Then molars of typodont bilaterally for the hy- the cast was used to construct the immobi- rax expanders; while for the Quad-Helix lization plate from acrylic resin (Major, and the W-Arch expanders, only 1st molars Italy) which was used to fix the posterior were banded .Then the impression was and anterior buccopalatal section of this poured with dental stone after ensuring plate to the 2nd molars and anterior teeth that bands were in their place in the im- and the surrounding simulated palatal sur- pression. On the cast model, the fitted face of typodont wax. Then this plate was bands were checked that were brought fixed to the metallic base using tightly fit down to the height of marginal ridges of

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the teeth and then fixed with soft wax. (15) screw was positioned at the midline (14) (Figure 2: A) (Figure 2: C). According to the manufac- For the Hyrax appliances, the turer’s instructions (Dentaurum, Germa- premolars and molars bands were joined ny), screw should be float freely 1-2mm on the palatal side with a piece of 1mm above the simulated palate roof. It should stainless steel wire. This wire was con- be ensured that the occlusal level is paral- toured from palatal surface of first molars lel. After that bands, hyrax screw and the to first premolars. (16) (Figure 2: B) Legs of metal bar were hold in position by plaster. the Hyrax screw (Dentaurum, Germany) All these components were soldered and were bent to fit the bands. The Hyrax then polished (Figure 2: D).

Figure (2): (A) Preformed bands are fitted on 1st bicuspids and 1st molar of typodont, (B) Joining the bands from palatal side with 1 mm SS wire and fixed with sticky wax, (C) Placing the Hyrax screw at the midline, (D) Holding the Hyrax components in position with plaster followed by soldering.

For the Quad-Helix and the W-Arch the W-Arch appliances and posterior heli- appliances, a prefabricated Quad-Helix of ces for the Quad-Helix appliances. The 0.9mm (Dentaurum, Germany) was used outer arms were rested against the palatal while the W-Arch was manually made out surfaces of the premolars and were sol- of 0.9mm round stainless wire. The W- dered to the palatal aspect of the 1st molar Arch expander had the same dimensions bands (18). (Figure 3: B and C) Then bands, as the Quad-Helix expander (17) (Figure 3: the Quad-Helix and the W-Arch main- A). These expanders were placed at the frames were hold in position by plaster middle of the cast. (9) The free wire was followed by soldering and polishing these ended adjacent to the posterior loops for components (Figure 3: D).

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Figure (3): (A) The W-Arch fabricated as the same dimension of the Quad-Helix, (B) Posi- tioning the Quad-Helix at the middle of the cast and adaptation, (C) Positioning the W-Arch at the middle of the cast and adaptation, (D) Holding the Quad-Helix and W-Arch compo- nents in position with plaster followed by soldering.

C. Preparation of Laboratorial Envi- to the wood table. This ruler was placed ronments perpendicular using a protractor to the Specially designed wood table of wood table and in the same level with the 30×21cm in dimension to which a metal occlusal plane of typodont teeth (Figure base of typodont articulator was attached 4). This ruler was used for the standardiza- vertically at 90° using a protractor. A tion of pre and postoperative images of the standard distance of 15cm between the occlusal view which were analyzed by digital camera and the base of typodont Autodesk AutoCAD© software. was maintained. A metallic ruler was fixed

Figure (4): Wood table to which a metal base of typodont articulator and a ruler were at- tached to it.

D. Standardization of the Tools seating the end of the clamping tweezers After each experiment, the typodont in a groove made on the buccal surface of teeth were repositioned to their original these teeth and driving the tooth to its po- position before expansion by immersing sition against the acrylic bite plane (Figure the typodont in the water bath, and then 5). Before starting expansion, the meas- the acrylic bite plane was seated on the urements were checked using digital ver- typodont. The premolars and first molars nia. teeth were brought to their positions by

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Figure (5): Reposition the teeth with the acrylic bite plane using clamping tweezers for driv- ing the tooth to its position.

For maxillary width measurements; the blue safety key, 8 quarter-turns. Each one distance between the palatal cusp tips of 1st quarter-turn brought about 0.25mm expan- and 2nd premolars bilaterally was sion (20). Both the Quad-Helix and the W- 30.6mm±0.1 and 34.3mm±0.1 respectively. Arch appliances were expanded 2mm; The distance between the mesiopalatal drawing a shape of the bands and arms of cusps tips of 1st molars bilaterally was the appliance before activation helps to 37.6mm±0.1. keep the shape of expanded appliance (21). For anteroposterior measurements; the distance between the buccal cusp tips of 1st Pre and Postoperative Image Analysis and 2nd premolars on the right and left sides Pre and postoperative images for all was 7.3mm±0.1 and 7mm±0.1 respective- trials were analyzed by Autodesk Auto- ly. The distance between the buccal and CAD© software. The images from occlusal mesiobuccal cusp tips of 2nd premolar and view were scaled in a manner that the dis- 1st molar on the right and left sides was tance of 10mm on the image was equal to 5.6mm±0.1 and 6mm±0.1 respectively. a distance of 10mm on the ruler. So, the For vertical measurements; the vertical linear measurements on the image were height between the base of typodont and equal to the real measurements in the buccal cusp tips of premolars and mesi- same plane. Digital images analyses were obuccal cusp tips of 1st molar was made by drawing three lines (Figure 6): 53mm±0.1 for both right and left sides. 1- Maxillary inter-first premolar line Water baths have controlled tempera- was drawn between the palatal cusp ture of about 54°C±2. Typodont was im- tips of the maxillary 1st premolars. mersed in the digital water bath for about 2- Maxillary inter-second premolar five minutes. Then the Typodont was im- line was drawn between the palatal mersed in a cool water of about 5°-10°C cusp tips of the maxillary 2nd premo- for five minutes (19). lars. 3- Maxillary inter-molar line was E. Activation of Expanders drawn between the mesiopalatal cusp The Hyrax appliance was expanded tips of the maxillary 1st molars. 2mm by activating the screw, using the

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Figure (6): Image analysis by Autodesk AutoCAD© software after drawing three lines: (A) maxillary inter-first premolar line; (B) maxillary inter-second premolar line and (C) maxillary inter-molar line

group. The Hyrax group revealed the Statistical Analysis highest value with a significant difference Statistical analysis was performed us- from the Quad-Helix and W-Arch groups. ing the (SPSS Version 11.5) statistical There was no significant difference be- program. The data were tested for their tween the remaining two groups (P≤0.05). normal distribution by using the Shapiro- nd The maxillary inter-2 premolars Wilks test. According to the results of this width change were 1.54±0.18 mm for the test, the data achieved were analyzed using Hyrax group, 0.64 ±0.44mm for the the one way ANOVA followed by Dun- Quad-Helix group and 0.51±0.24mm for can's multiple range tests to locate the sig- the W-Arch group. The Hyrax group dis- nificant differences among means of these played the highest value with a significant 3 groups. difference from the Quad-Helix and W- Arch groups. There was no significant dif- RESULTS ference between the remaining two groups Descriptive statistics that includes (P≤0.05). st mean, standard deviation, minimum and The maxillary inter-1 molar width maximum value of maxillary inter-1st change were 0.96±0.22mm for the Hyrax premolar, inter-2nd premolar and inter-1st group, 0.52±0.39mm for the Quad-Helix molar width changes measured for Hyrax, group and 0.43 ±0.27mm for the W-Arch Quad-Helix and W-Arch groups are listed group. The Hyrax group showed the high- in Table (1). est value with a significant difference from The maxillary inter-1st premolar width the Quad-Helix and W-Arch groups. There changes were 1.41±0.23mm for the Hyrax was no significant difference between the group, 0.93±0.33mm for the Quad-Helix remaining two groups (P≤0.05). group and 0.92±0.38mm for the W-Arch

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Table (1): Descriptive statistic of the parameters measured in the study. Group Variable Mean ±Std. Dev. Minimum Maximum Inter-maxillary 1st premolar 1.41 ±0.23 1.01 1.69 width changes (mm) Inter-maxillary 2nd premolars Hyrax 1.54 ±0.18 1.21 1.73 width change (mm) Inter-maxillary 1st molar width 0.96 ±0.22 0.50 1.22 change (mm) Inter-maxillary 1st premolar 0.93 ±0.33 0.47 1.40 width changes (mm) Quad- Inter-maxillary 2nd premolars 0.64 ±0.44 0.10 1.43 Helix width change (mm) Inter-maxillary 1st molar width 0.52 ±0.39 0.10 1.25 change (mm) Inter-maxillary 1st premolar 0.92 ±0.38 0.20 1.41 width changes (mm) Inter-maxillary 2nd premolars W-Arch 0.51 ±0.24 0.17 0.80 width change (mm) Inter-maxillary 1st molar width 0.43 ±0.27 0.10 0.80 change (mm) (mm) = millimeter

Table (2): Comparison differences among Hyrax, Quad-helix and W-Arch. ±Std. F- P- Duncan’s Variable Group Mean Dev. Value value Group Hyrax 1.41 0.23 B Inter-maxillary 1st pre- Quad- molar width change 0.93 0.33 7.356 0.003* A Helix (mm) W-Arch 0.92 0.38 A Hyrax 1.54 0.18 B Inter-maxillary 2nd pre- Quad- molar width change 0.64 0.44 32.575 0.000* A Helix (mm) W-Arch 0.51 0.24 A Hyrax 0.96 0.22 B Inter-maxillary 1st molar Quad- 0.52 0.39 8.499 0.001* A width change (mm) Helix W-Arch 0.43 0.27 A * P ≤ 0.05; (mm) = millimeter

Quad-Helix and the W-Arch expanders DISCUSSION regarding those changes. The outcomes of the present study This may be attributed to the possibil- showed that there was a significant differ- ity that a larger force is applied by the Hy- ence regarding the rate of maxillary inter- rax expander on the premolars and molars 1st premolars width change, (1stPWC), the nd teeth resulting in more expansion rate. An rate of maxillary inter-2 premolars width activation of the Hyrax appliance in each change, (2ndPWC) and the rate of maxil- st quarter turn, at least 900g of force is ap- lary inter-1 (22) molars width change, plied to the teeth ; while the Quad-Helix (1stMWC), between the Hyrax expander produces forces between 180g and 667g, and the other two expanders, while there depending on the material used, and the was no significant difference between the

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length and the size of the wire. (23) For the er researches was contributed to the fact W-Arch expanders, activation of W-Arch that the present study is conducted on ty- appliances constructed from 0.036" diame- podont and after an activation of 2mm on- ter arch wires produced forces approxi- ly, while all mentioned studies are con- mately of 383.4g. (17) So, larger forces of ducted clinically on patients; and until expansion applied by the Hyrax appliance complete expansion and treatment of pos- is contribute to the design of the Hyrax terior which require an activation which allow delivery of large forces than of expanders for more than 2mm. both the Quad-Helix and the W-Ach ap- pliances. CONCLUSION When examining arch width changes, According to the present study, the we observed that the Hyrax appliance in- Hyrax expander increases the intermaxil- creased the 1stPWC at a range of 1.41mm, lary premolars and molars width more re- while the Quad-Helix and the W-Arch ap- liably than the Quad-Helix and the W- pliances resulted in an increase at 1stPWC Arch expanders. Both Quad-Helix and W- at a rate of 0.93mm and 0.92mm respec- Arch expanders increases the inter premo- tively. The results of the Quad-Helix ex- lars and molars width at similar rates. pander of the present study are close to a REFERENCES (24) study by Bjerklin , who saw an increase 1. Mikulencak DM. A comparison of of 1.3 mm in the 1stPWC; and are less maxillary arch width and molar tip- than other studies which reported an in- ping changes between rapid maxillary crease of 1stPWC range from 3.1mm to expansion and fixed appliances vs. the (25, 26) 5.8mm. Damon system. Master thesis submit- The Hyrax appliance increased the ted to the faculty of the graduate 2ndPWC at a range of 1.54mm, while the school of Saint Louis University, Quad-Helix and W-Arch appliances re- 2006. sulted in an increase in 2ndPWC at a rate 2. Woller JL. An assessment of the max- of 0.64mm and 0.51mm respectively. In a illa after rapid maxillary expansion us- (26) study by Li and Lin , the 2ndPWC in- ing cone beam computed tomography creased at a mean of 4.4mm. in growing children. Master thesis The Hyrax expander in this study in- submitted to the faculty of the gradu- creased the 1stMWC at a mean of 0.96mm ate school of Saint Louis University, which is less than reported by other studies 2009. which accomplished intermolar expansion 3. Kurt G, Altug-Ataç AT, Ataç MS, (27, 28) more than 4mm. The W-Arch and Karasu HA. Stability of surgically as- the Quad-Helix appliances increased the sisted rapid maxillary expansion and 1stMWC at a mean of 0.43mm and orthopedic maxillary expansion after 3 0.52mm respectively. Some studies years’ follow-up. Angle Orthod. 2010; achieved an increase of more than 3mm in 80(4): 613-619. st (24, 26) the 1 MWC ; while others achieved 4. Suri L, Taneja P. Surgically assisted more than 4mm with the Quad-Helix ap- rapid palatal expansion: a literature (28, 29, 30) pliances. review. Am J Orthod Dentofacial Or- The findings of the present study disa- thop. 2008; 1333(2): 290-302. (27) gree with Hyunh et al. and Wong et al. 5. Gill D, Naini F, McNally M, Jones A. (28) , who stated that both the Hyrax and The Management of Transverse Max- Quad-Helix appliances showed similar illary Deficiency. Dent Update. 2004; amount of intermolar expansion after 31(9): 516–523. SME. A likely explanation is that SME 6. Bell RA. A review of maxillary ex- has carried out in young patients at pre- pansion in relation to rate of expansion adolescent, so suture has little inter- and patient's age. Am J Orthod Den- digitation and opens easily under light tofacial Orthop. 1982; 81(1): 32-37. (27) forces regardless of expander type. 7. Karaman AI. The effects of nitanium All mentioned studies have carried out maxillary expander appliances on den- clinically on patients after SME. This dif- tofacial structures. Angle Orthod. ference between the present study and oth- 2002; 72(4): 344-354.

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