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Orthodontic treatment for posterior crossbites (Review)

Agostino P, Ugolini A, Signori A, Silvestrini-Biavati A, Harrison JE, Riley P

Agostino P, Ugolini A, Signori A, Silvestrini-Biavati A, Harrison JE, Riley P. Orthodontic treatment for posterior crossbites. Cochrane Database of Systematic Reviews 2014, Issue 8. Art. No.: CD000979. DOI: 10.1002/14651858.CD000979.pub2.

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Orthodontic treatment for posterior crossbites (Review) Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

T A B L E O F C O N T E N T S HEADER...... 1 ABSTRACT...... 1 PLAIN LANGUAGE SUMMARY...... 2 SUMMARY OF FINDINGS...... 4 BACKGROUND...... 8 OBJECTIVES...... 9 METHODS...... 9 RESULTS...... 11 Figure 1...... 12 Figure 2...... 15 DISCUSSION...... 18 AUTHORS' CONCLUSIONS...... 19 ACKNOWLEDGEMENTS...... 19 REFERENCES...... 20 CHARACTERISTICS OF STUDIES...... 22 DATA AND ANALYSES...... 41 Analysis 1.1. Comparison 1 Fixed rapid (Haas) versus fixed rapid (Hyrax), Outcome 1 Molar expansion (3 months aDer completion 42 of expansion phase)...... Analysis 2.1. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 1 Crossbite correction.... 42 Analysis 2.2. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 2 Molar expansion...... 42 Analysis 2.3. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 3 Canine expansion...... 43 ADDITIONAL TABLES...... 43 APPENDICES...... 45 WHAT'S NEW...... 48 HISTORY...... 48 CONTRIBUTIONS OF AUTHORS...... 49 DECLARATIONS OF INTEREST...... 49 SOURCES OF SUPPORT...... 49 DIFFERENCES BETWEEN PROTOCOL AND REVIEW...... 49 INDEX TERMS...... 49

Orthodontic treatment for posterior crossbites (Review) i Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

[Intervention Review] Orthodontic treatment for posterior crossbites

Paola Agostino1, Alessandro Ugolini2, Alessio Signori3, Armando Silvestrini-Biavati2, Jayne E Harrison4, Philip Riley5

1Private practice, Chiavari, Italy. 2Orthodontics Department, University of Genoa, Genoa, Italy. 3Unit of Biostatistics, Health Sciences Department, University of Genoa, Genoa, Italy. 4Orthodontic Department, Liverpool University Dental Hospital, Liverpool, UK. 5Cochrane Oral Health Group, School of Dentistry, The University of Manchester, Manchester, UK

Contact address: Alessandro Ugolini, Orthodontics Department, University of Genoa, Largo Rosanna Benzi 10, Genoa, 16132, Italy. [email protected].

Editorial group: Cochrane Oral Health Group. Publication status and date: New search for studies and content updated (conclusions changed), published in Issue 8, 2014.

Citation: Agostino P, Ugolini A, Signori A, Silvestrini-Biavati A, Harrison JE, Riley P. Orthodontic treatment for posterior crossbites. Cochrane Database of Systematic Reviews 2014, Issue 8. Art. No.: CD000979. DOI: 10.1002/14651858.CD000979.pub2.

A B S T R A C T

Background A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. When it aJects one side of the mouth, the lower jaw may have to move to one side to allow the back teeth to meet together. Several treatments have been recommended to correct this problem. Some treatments widen the upper teeth while others are directed at treating the cause of the posterior crossbite (e.g. breathing problems or sucking habits). Most treatments have been used at each stage of dental development. This is an update of a Cochrane review first published in 2001.

Objectives To assess the eJects of orthodontic treatment for posterior crossbites.

Search methods We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 21 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1), MEDLINE via OVID (1946 to 21 January 2014), and EMBASE via OVID (1980 to 21 January 2014). We searched the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry Platform for ongoing trials. We placed no restrictions on the language or date of publication when searching the electronic databases.

Selection criteria Randomised controlled trials (RCTs) of orthodontic treatment for posterior crossbites in children and adults.

Data collection and analysis Two review authors, independently and in duplicate, screened the results of the electronic searches, and extracted data and assessed the risk of bias of the included studies. We attempted to contact the first named authors of the included studies for missing data and for clarification. We used risk ratios (RR) and 95% confidence intervals (CIs) to summarise dichotomous (event) data, and mean diJerences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-eJect models (we would have used random- eJects models if we had included four or more studies in a meta-analysis) when comparisons and outcomes were suJiciently similar.

Main results We included 15 studies, of which two were at low risk of bias, seven were at high risk of bias and six were unclear.

Fixed appliances with mid-palatal expansion

Orthodontic treatment for posterior crossbites (Review) 1 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Nine studies tested fixed appliances with mid-palatal expansion against each other. No study reported a diJerence between any type of appliance.

Fixed versus removable appliances

Fixed quad-helix appliances may be 20% more likely to correct crossbites than removable expansion plates (RR 1.20; 95% CI 1.04 to 1.37; two studies; 96 participants; low-quality evidence).

Quad-helix appliances may achieve 1.15 mm more molar expansion than expansion plates (MD 1.15 mm; 95% CI 0.40 to 1.90; two studies; 96 participants; moderate-quality evidence).

There was insuJicient evidence of a diJerence in canine expansion or the stability of crossbite correction.

Very limited evidence showed that both fixed quad-helix appliances and removable expansion plates were superior to composite onlays in terms of crossbite correction, molar and canine expansion.

Other comparisons

Very limited evidence showed that treatments were superior to no treatment, but there was insuJicient evidence of a diJerence between any active treatments.

Authors' conclusions There is a very small body of low- to moderate-quality evidence to suggest that the quad-helix appliance may be more successful than removable expansion plates at correcting posterior crossbites and expanding the inter-molar width for children in the early mixed dentition (aged eight to 10 years). The remaining evidence we found was of very low quality and was insuJicient to allow the conclusion that any one intervention is better than another for any of the outcomes in this review.

P L A I N L A N G U A G E S U M M A R Y

Orthodontic treatment for posterior crossbites

Review question

We conducted this review to assess the eJects of diJerent orthodontic treatments for correcting posterior crossbites.

Background

Posterior crossbite is when the top back teeth bite down inside the bottom back teeth. It occurs when the top teeth or jaw are narrower than the bottom teeth and can happen on one or both sides of the mouth. The condition aJects between 1% and 16% of children who only have their baby teeth. Most posterior crossbites (50% to 90%) remain even when the permanent teeth erupt. In a minority of children, the problem self corrects.

In order to obtain a more comfortable bite, the lower jaw shiDs to one side into a position that allows more teeth to come into contact. However, this shiDing of the lower jaw may lead to tooth grinding, and this may lead to other dental problems including the tooth surface being worn away, abnormal growth and development of the teeth and jaws, and jaw joint problems.

Therefore, we need to find safe and eJective treatments to correct posterior crossbites or expand the top back teeth, or both. One way of doing this is using orthodontic treatments. This can be more eJective in children because the two halves of the roof of the mouth have not fully joined yet, so the top back teeth can be expanded more easily. Orthodontic treatments can also be used to treat posterior crossbites in adults, but they are more likely to need surgical treatments, which are not the focus of this review.

Study characteristics

Authors from the Cochrane Oral Health Group carried out this review update of existing studies and the evidence is current up to 21 January 2014. It includes 15 studies published from 1984 to 2013. Nine of these studies compared fixed (always in the mouth) appliances either against diJerent fixed appliances, or against the same fixed appliance but comparing diJerent rates of expansion. Two studies compared a fixed appliance with a removable appliance. The remaining four studies evaluated other comparisons that were more diJicult to classify.

Key results

There is some evidence to suggest that the quad-helix (fixed) appliance may be more successful than removable expansion plates at correcting posterior crossbites and expanding the top back teeth for children with a mixture of baby and adult teeth (aged eight to 10 years). The remaining evidence we found did not allow the conclusion that any one treatment is better than another.

Quality of the evidence

Orthodontic treatment for posterior crossbites (Review) 2 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

The evidence presented is mostly of low to very low quality due to the small amount of available studies and issues with the way in which they were conducted.

Orthodontic treatment for posterior crossbites (Review) 3 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. C O o r t p S U M M A R Y O F F I N D I N G S h y o r i d g o h n t

L C t © i c

i o

2 Summary of findings for the main comparison. Fixed appliances compared with other fixed appliances for treating posterior crossbites

t b 0 r c 1 e r 4 h a

a t T r m h Fixed appliances compared with other fixed appliances for treating posterior crossbites r a e e y

n C n t o

e c f o h Patient or population: Children with posterior crossbites (adults would be included in the review but no studies with adults were found) r r a p n o e s B I T

t n C Settings: Typically university orthodontic/dental clinics r e e f u o t o r t s l i r e l t o m a e r r b d h Intervention: Fixed appliance e

c o e d e r r a v

d o a l i t d e t s h i c e s o .

Comparison: The same fixed appliance attached differently or expanded at different speeds or a different fixed appliance i n b s n c i i o . e t

P e n . s s u . b (

R Outcomes Illustrative compara- Relative No of Qual- Comments l i e s h v tive risks (95% CI) effect partici- ity of e i e d w

(95% pants the evi- b ) y

J As- Corre- CI) (stud- dence o h ies) (GRADE)

n sumed sponding

W risk risk i l e y

S Group A Group B o n s ,

t Molar expansion N/A N/A N/A 53 ⊕⊝⊝⊝ 2 studies (1 high risk of bias; 1 unclear), which were not possible to pool in a d . (2) very meta-analysis due to no reporting of variance in 1 study. Imprecision due to (mm) low low sample sizes. Different timings of follow-up after completion of expansion. Both studies reported no difference in molar expansion (rapid expansion) banded Hyrax (tooth borne) versus bonded Hyrax (tooth/tissue borne)

Molar expansion The The mean N/A 27 ⊕⊝⊝⊝ 2 studies at unclear risk of bias with serious inconsistency (I2 = 94%) and im- C

mean ex- expansion (2) very precision due to low sample size o c

(mm) pansion in the Hyrax low h r a

ranged groups was n e

(3 months after comple- across 0.7 mm D a

tion of expansion phase) t the Haas lower a b a

groups (1.66 lower s (rapid expansion) tooth- e

from to 0.25 high- o f

tissue borne (Haas) ver- S

6.5 to er) y sus tooth borne (Hyrax) s t 8.49 mm e m a t i c

N/A N/A N/A N/A N/A N/A The remaining comparisons were all single studies (Additional Table 1). The R e v

quality of the evidence (GRADE) for all comparisons and outcomes in Addi- i e w

4 tional Table 1 is ⊕⊝⊝⊝ very low (all at unclear or high risk of bias with impre- s

C O o r t p cision due to low sample sizes). None of these studies showed a statistically h y o r

i significant difference for any outcome d g o h n t

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CI: confidence interval; N/A: not applicable. t b 0 r c 1 e r 4 h a

a t T r m h

GRADE Working Group grades of evidence r a e e y

n C High quality: Further research is very unlikely to change our confidence in the estimate of effect. n t o

e c f o h Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. r r a p n Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. o e s B I T

t n C r e

e Very low quality: We are very uncertain about the estimate. f u o t o r t s l i r e l t o m a e r r b d h e

c o e d e r r a v

d o a l i t d e t s h i c e s o . i n b s n c i i o . e t

P e n . s s u

Summary of findings 2. Fixed appliances compared with removable appliances for treating posterior crossbites . b ( R l i e s h v e i e d Fixed appliances compared with removable appliances for treating posterior crossbites w b ) y

J o

h Patient or population: Children with posterior crossbites (adults would be included in the review but no studies with adults were found) n

W i l Settings: Public Dental Health Service and university orthodontic/dental clinics e y

S Intervention: Fixed appliance o n s ,

L Comparison: Removable appliance t d . Outcomes Illustrative comparative risks* (95% CI) Relative No of Qual- Comments effect partici- ity of Assumed risk Corresponding risk (95% pants the evi- CI) (stud- dence Removable - slow Fixed - slow expan- ies) (GRADE) expansion (expansion (quad-helix) sion plate) C o

Crossbite correc- 833 per 1000 1000 per 1000 RR 1.2 96 ⊕⊕⊝⊝ 2 studies at low risk of bias, but with serious inconsistency (I2 = c h r tion (867 to 1000) (1.04 to (2) low 68%) and imprecision due to low sample size a n e

1.37) D

(Follow-up after a t a

retention period, b a s

therefore, it was e

o f

variable) S y s t e Molar expansion The mean expan- The mean expansion N/A 96 ⊕⊕⊕⊝ 2 studies at low risk of bias, but with imprecision due to low m a t i

sion ranged across in the fixed appliance (2) moder- sample size c

(mm) R the removable ap- group was ate e v i pliance groups 1.15 mm higher e w 5 s

C O o r t p (Follow-up after from 3.09 to 3.5 (0.4 to 1.9 higher) h y o r

i retention period, mm d g o h n t therefore, it was

L C t © i c

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2 variable)

t b 0 r c 1 e r 4 h a

a t T r m h r a e e y

2 n

C Canine expansion The mean expan- The mean expansion N/A 96 ⊕⊕⊝⊝ 2 studies at low risk of bias, but with serious inconsistency (I = n t o

e c f sion ranged across in the fixed appliance (2) low

o 91%) and imprecision due to low sample size h r r

(mm) a

p the removable ap- group was n o e s B I T

pliance groups 0.19 mm higher t n C r e e f u o (Follow-up after t o r t s l from 1.43 to 2.7 (0.47 lower to 0.85 i r e l t o m a e retention period, r r b d h e

mm higher)

c o e d e r r a v therefore it was d o a l i t d e t s h i c e s o variable) . i n b s n c i i o . e t

P e n . s s u . b ( N/A N/A N/A N/A N/A N/A 1 of the 2 studies in this comparison also measured stability of R l i e s h v crossbite correction (relapse 12 months after correction). No e i e d

w statistically significant difference was found (Additional Table b ) y

2) J o h n

The other study also compared the fixed and removable appli- W i l

e ances to composite onlays for crossbite correction, molar ex- y

& pansion and canine expansion. All results were statistically sig-

S o nificant in favour of fixed and removable appliances (Additional n s

, Table 2)

L t d . The quality of the evidence (GRADE) for all comparisons and outcomes in Additional Table 2 is ⊕⊝⊝⊝ very low

*The basis for the assumed risk is the removable group event rate. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; N/A: not applicable; RR: risk ratio.

GRADE Working Group grades of evidence

High quality: Further research is very unlikely to change our confidence in the estimate of effect. C o

Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. c h r Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. a n e

Very low quality: We are very uncertain about the estimate. D a t a b a s e

o f

S y s

Summary of findings 3. Other comparisons for treating posterior crossbites t e m a t i Other comparisons for treating posterior crossbites c

R e v i e

Patient or population: Children with posterior crossbites (adults would be included in the review but no studies with adults were found) w 6 s

C O o r t p Settings: Public Dental Health Service and university/hospital orthodontic/dental clinics h y o r i d g o h n t

Out- Illustrative compar- Relative No of Qual- Comments L C t © i c

i o 2

comes ative risks (95% CI) effect partici- ity of t b 0 r c 1 e r

4 (95% pants the evi- h a

a t T r m h CI) (stud- dence As- Corre- r a e e y

n C sumed spond- ies) (GRADE) n t o

e c f o h risk ing risk r r a p n o e s B I T

t n C r e e

Group A Group B f u o t o r t s l i r e l t o m a e r r b d h e

c o e d e r r a v N/A N/A N/A N/A N/A N/A The comparisons were all single studies (Additional Table 3). The quality of the evidence (GRADE) d o a l i t d e t s h i c e s o for all comparisons and outcomes in Additional Table 3 is ⊕⊝⊝⊝ very low (all at high risk of bias . i n b s n c i i o . e t

with imprecision due to low sample sizes) P e n . s s u . b ( R l i e s • 1 study compared a removable appliance with spring-loaded screw against a conventional screw h v e i e

d but the results were inadequately reported w b ) y • 1 study compared quad-helix plus multi-bracket against expansion arch plus multi-bracket for

J o

h molar/canine expansion with no statistically significant results n

W • The final 2 studies showed statistically significant results against no treatment for fixed bond- i l e ed Hyrax appliance followed by U-bow activator (molar/canine expansion), and for grinding or y

& grinding plus expansion plate (crossbite correction)

S o n s ,

L GRADE Working Group grades of evidence t d

. High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

CI: confidence interval; N/A: not applicable.

C o c h r a n e

D a t a b a s e

o f

S y s t e m a t i c

R e v i e w 7 s

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B A C K G R O U N D (upper jaw) arch, removal of any occlusal interferences and elimination of the functional displacement of the mandible. Description of the condition Maxillary expansion treatment initiated during the early mixed Posterior crossbite is the term used to describe the situation dentition stage (children younger than eight years of age) may when the top back teeth bite inside the bottom back teeth. A require the use of lower forces to achieve expansion of the upper posterior crossbite occurs when the top teeth or jaw are narrower arch because the mid-line bony suture has not yet fused. However, than the bottom teeth and can happen on one (unilateral) or obtaining co-operation with treatment may be more diJicult in both (bilateral) sides of the mouth. The prevalence of posterior younger children and treatment may be complicated by the loss crossbites is between 1% and 16% of children who only have their of deciduous teeth. In older children (aged 12 years and above) baby teeth, and is likely to be higher in white populations compared who are in the early permanent dentition, greater forces may with children of African or Asian ethnicity (Malandris 2004). Most be required to achieve maxillary expansion. Maxillary expansion posterior crossbites (50% to 90%) persist when the permanent can be achieved using either fixed or removable appliances and teeth erupt, though, in a minority of children, the malocclusion self expansion can be either rapid or slow. Expansion of the top jaw corrects. is termed 'rapid' when expansion takes place at a rate of 0.5 mm per day, and 'slow' when expansion takes place at a rate of 0.5 mm A functional posterior crossbite occurs when there is an per week. Braces that can bring about this expansion are fixed to interference between two or more teeth when an individual closes the back teeth by either metal bands around the individual teeth their jaws together. In order to obtain a more comfortable bite, the (banded rapid/slow maxillary expansion) or acrylic splints over mandible (lower jaw) shiDs to one side into a position that allows several teeth (bonded rapid/slow maxillary expansion) joined by more teeth to come into contact. However, this displacement may a wire framework attached to a screw in the mid-line that can be increase the likelihood of the individual developing bruxism (tooth opened to expand the top jaw. grinding), which may lead to other dental problems including the tooth surface being worn away (Malandris 2004), abnormal growth Removal of occlusal interferences involves grinding of teeth and development of the teeth and jaws, and jaw joint problems. (usually deciduous teeth) to enable the jaws to bite together in a more normal position. The reported success rate of this approach While it is unlikely that young children with a posterior crossbite varied widely between 27% and 64% (Kennedy 2005; Lindner 1989). will experience any pain or have problems with chewing, there Alternatively, composite onlays can be placed to prevent the jaw has been concern that the abnormal movement of the lower from shiDing when interferences exist. jaw associated with a crossbite could potentially have long-term eJects on the growth and development of the teeth and jaws. Where functional displacement of the mandible is associated with The strain on the jaw muscles and joints due to the abnormal reversible causes such as non-nutritive sucking habits (sucking on movement and position of the lower jaw may lead to skeletal facial a dummy, thumb, finger(s), etc.), eliminating the causal behaviour asymmetries that can be corrected during adulthood only by means is a desirable adjunct to orthodontic treatment. of a combination of orthodontics and maxillofacial surgery. How the intervention might work Some studies have reported a correlation between posterior crossbite with a shiD on closure and temporomandibular joint Expansion of the maxillary arch can be achieved through use problems in later life, for example pain, clicking or locking of of either fixed or removable appliances (see Appendix 1 for a the jaw joints. Such problems have many causes but studies of description of appliances). These have expansion screws that are teenagers and adults have shown that some people with a crossbite adjusted during treatment to increase the width of the maxillary may have an increased risk of developing jaw joint problems and arch. Expansion may be either rapid (one-quarter turn of the show more signs and symptoms of these problems (Egermark expansion screw one or two times per day, giving 0.5 mm expansion 1990; McNamara 1997; Ninou 1994; O'Bryn 1995; Pullinger 1993). per day) over two to six weeks or slow (one-quarter turn twice per However, some more recent studies have been less conclusive week, giving 0.5 mm expansion per week) over six to 12 weeks. regarding an association between posterior crossbites and jaw Overexpansion may be appropriate to allow for some relapse aDer problems (Gesch 2004; Iodice 2013; Thilander 2002; Thilander the appliance is removed. The use of maxillary expansion at the 2012). stage of the early mixed dentition may also have the benefit of reducing crowding of the permanent dentition. A posterior crossbite may develop or improve at any time from when the deciduous (baby) teeth come into the mouth to when the Orthodontic appliances may also be used to correct the sideways permanent (adult) teeth come through (Heikinheimo 1987; Kurol displacement of the mandible, which may reduce the pressure on 1992; Leighton 1966; Thilander 1984). It is unclear what causes the temporomandibular joint. posterior crossbites but they may be due to skeletal, soD tissue, dental or respiratory factors, or develop as the result of a habit (e.g. Why it is important to do this review thumb sucking) or some pathology (Bresolin 1983; Cheng 1988; A crossbite is a common transverse feature seen in malocclusions Modeer 1982; Ogaard 1994; Subtelny 1980). in the posterior region of the dental arch. There is still debate about the optimum timing of orthodontic treatment, the use of Description of the intervention either fixed or removable appliances, and the type of appliance that As described above, a posterior crossbite may self correct but, leads to the best outcomes for the person. This updated systematic as self correction occurs in only a very small minority of cases, review will summarise the evidence available from randomised treatment of this malocclusion can be recommended. Treatment controlled trials to inform treatment decision making. The of a posterior crossbite usually involves expansion of the maxillary Cochrane Oral Health Group recently carried out a prioritisation Orthodontic treatment for posterior crossbites (Review) 8 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews exercise for their portfolio of orthodontic reviews, and this review March 2011) (Higgins 2011). Details of the MEDLINE search are was ranked in the top 10 most important orthodontic reviews by provided in Appendix 2. The search of EMBASE was linked to the an international panel of oral health professionals, the majority of Cochrane Oral Health Group filter for identifying RCTs. whom were extremely experienced and internationally renowned orthodontists. Electronic searches We searched the following electronic databases: This is an update of a Cochrane review first published in 2001. • the Cochrane Oral Health Group's Trials Register (to 21 January O B J E C T I V E S 2014) (Appendix 3); To assess the eJects of orthodontic treatment for posterior • the Cochrane Central Register of Controlled Trials (CENTRAL) crossbites. (The Cochrane Library, 2014, Issue 1) (Appendix 4); • MEDLINE via OVID (1946 to 21 January 2014) (Appendix 2) M E T H O D S • EMBASE via OVID (1980 to 21 January 2014) (Appendix 5).

Criteria for considering studies for this review We manually checked all the references lists of the included studies Types of studies to identify any additional studies. We included randomised controlled trials (RCTs) of parallel design We placed no restrictions on the language or date of publication that assessed orthodontic treatments to correct a posterior when searching the electronic databases. crossbite or expand the top back teeth, or both. We included studies irrespective of language or publication status. Searching other resources We searched the following databases for ongoing trials (see Types of participants Appendix 6 for the search strategy): We included RCTs of children and adults with a posterior crossbite, without a Class III skeletal relationship, cleD lip or palate (or both) • US National Institutes of Health Trials Register (clinicaltrials.gov) or other syndrome associated with craniofacial anomalies. (to 21 January 2014); • The WHO Clinical Trials Registry Platform (apps.who.int/ Types of interventions trialsearch/default.aspx) (to 21 January 2014).

We included studies of any orthodontic or dentofacial orthopaedic We handsearched the following journals from 1970 to 2012: (not surgical) treatment used to correct posterior crossbites or expand the top back teeth, or both, when compared against • European Journal of Orthodontics; another such treatment or no treatment. • American Journal of Orthodontics and Dentofacial Orthopedics; Types of outcome measures • Orthodontics and Craniofacial Research; • The Angle Orthodontist. Primary • Correction of the posterior crossbite. In the previous version of this review we also handsearched:

Secondary • British Journal of Orthodontics; • Journal of Orthodontics. • Expansion of the upper jaw/teeth measured as changes in the width between the molars or canines, or both. We also searched personal references. We contacted the • Stability of crossbite correction. investigators of the included studies by email to ask for additional • Signs and symptoms of temporomandibular joint dysfunction details of their trials and for any information they may have about (e.g. pain, clicking, locking of the jaw joints, problems eating). any further published and unpublished trials. • Signs and symptoms of respiratory disease (e.g. mouth Data collection and analysis breathing, nasal airway resistance). • Quality of life (using any validated measurement tool). Selection of studies Two review authors screened the titles and abstracts of the Search methods for identification of studies results of the searches, independently and in duplicate. We For the identification of studies included or considered for this obtained full-text copies of all studies that appeared to meet review, we developed detailed search strategies for each database the inclusion criteria, and of all those that were unclear due searched. These were based on the search strategy developed to insuJicient information in the title or abstract, or both. Two for MEDLINE (OVID) but revised appropriately for each database. review authors assessed the full-text papers independently and in The search strategy used a combination of controlled vocabulary duplicate in order to ensure that they met the inclusion criteria. and free-text terms and was linked with the Cochrane Highly We contacted study authors for clarification or missing information Sensitive Search Strategy (CHSSS) for identifying RCTs in MEDLINE: where necessary and possible. We resolved any disagreements by sensitivity maximising version (2008 revision) as referenced in discussion. A member of The Cochrane Collaboration translated Chapter 6.4.11.1 and detailed in box 6.4.c of the Cochrane Handbook any non-English language studies. We recorded any studies that did for Systematic Reviews of Interventions Version 5.1.0 (updated not meet the inclusion criteria at this stage, along with the reasons, in the Characteristics of excluded studies table. Orthodontic treatment for posterior crossbites (Review) 9 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Data extraction and management • Unclear risk of bias (plausible bias that raises some doubt about the results) if one or more key domains were assessed as at Two review authors extracted data from the included studies, unclear risk of bias. independently and in duplicate, using a piloted data extraction form. We resolved any disagreements through discussion. We • High risk of bias (plausible bias that seriously weakens contacted study authors for clarification or missing information confidence in the results) if one or more key domains were where necessary and possible. assessed as at high risk of bias.

We entered the following extracted data into the Characteristics of We have presented the results of our risk of bias assessments included studies table. graphically.

• Study design, location, number of centres, recruitment period, Measures of treatment e>ect funding, experience level of clinician. For dichotomous outcomes (e.g. posterior crossbite corrected • Inclusion and exclusion criteria, age, gender, number of or not), we expressed the estimate of treatment eJect as risk participants randomised to each group, number of participants ratios (RR) with 95% confidence intervals (CI). For continuous evaluated. outcomes (e.g. width between the molars), we used the means and • Details of the type of intervention/comparator, timing, duration. standard deviations (SD) reported in the studies to calculate mean • Details of the outcomes reported, including method of diJerences (MD) with 95% CIs. assessment, and time(s) assessed. Dealing with missing data • Sample size calculations, any other notable details. Where possible, we attempted to contact the author(s) of studies to Assessment of risk of bias in included studies obtain missing data or for clarification. We performed the analyses using only the available data (ignoring missing data); however, we Two review authors assessed the risk of bias of each included intended to use methods for estimating missing SDs as described study, independently and in duplicate, following the domain-based in Section 7.7.3 of the Cochrane Handbook for Systematic Reviews two-part tool described in the Cochrane Handbook for Systematic of Interventions (Higgins 2011), if appropriate. We did not use any Reviews of Interventions (Higgins 2011). We contacted study further statistical methods or carry out any further imputation to authors for clarification or missing information where necessary account for missing data. and possible. We compared our assessments and discussed and resolved any inconsistencies between the review authors. Assessment of heterogeneity We assessed the following six domains of risk of bias for each Where meta-analyses were performed, we assessed heterogeneity included study. by visual inspection of the forest plots. If there was a lack of overlap of the CIs, we considered heterogeneity to be present. We assessed • Random sequence generation (selection bias). heterogeneity statistically by means of a Chi2 test, where a P value • Allocation concealment (selection bias). < 0.1 indicated statistically significant heterogeneity. We quantified • Blinding of outcome assessment (detection bias). heterogeneity using the I2 statistic. An approximate guide to the • Incomplete outcome data (attrition bias). interpretation of the I2 statistic given in the Cochrane Handbook • Selective reporting (reporting bias). for Systematic Reviews of Interventions is: 0% to 40% might not be important; 30% to 60% may represent moderate heterogeneity; • Other bias. 50% to 90% may represent substantial heterogeneity and 75% to We did not consider the blinding of participants and personnel 100% may represent considerable heterogeneity (Higgins 2011). (performance bias) as the interventions being compared in all Assessment of reporting biases studies were diJerent and it would not have been possible to blind them as to which group they were allocated. Therefore, a We have already described the assessment of within-study risk of performance bias is possible in all of the included studies. reporting bias in the section Assessment of risk of bias in included However, it should be possible for outcome assessors to be blinded studies. if measuring casts/models or radiographs or both, if the appliances had been removed. Therefore, we focused on assessing the risk of In order to assess reporting biases that can occur when the detection bias. publishing (or not publishing) of research findings is related to the results (e.g. a study with a non-significant result may not be We completed a 'Risk of bias' table for each included study. For published), we would have created a funnel plot to check for each of the above domains, we described what was reported to asymmetry (Egger 1997; Higgins 2011), provided there were more have happened in the study and this formed the rationale for our than 10 studies in a meta-analysis. corresponding judgement of 'low risk' of bias, 'high risk' of bias or 'unclear risk' of bias for each domain. Data synthesis We only carried out a meta-analysis when studies of similar We categorised overall risk of bias in any included study according comparisons reported the same outcomes. We combined MDs for to the following. continuous outcomes, and RRs for dichotomous outcomes, using • Low risk of bias (plausible bias unlikely to seriously alter the a fixed-eJect model when there were fewer than four studies, or a results) if all key domains were assessed as at low risk of bias. random-eJects model when there were four or more studies. We summarised single-study comparisons in additional tables.

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Subgroup analysis and investigation of heterogeneity evidence of each of the main outcomes for each comparison as high, moderate, low or very low. In future updates, if suJicient data are available for each comparison and outcome, we will conduct subgroup analyses R E S U L T S according to age, gender and the degree of severity of maxillary transversal deficiency. Description of studies Sensitivity analysis Results of the search In future updates, if suJicient data are available for each The electronic searches retrieved 779 references to studies. ADer comparison and outcome, we will assess the robustness of the removing duplicates, this was reduced to 515. We obtained two results by excluding studies at high and unclear risk of bias from the additional reports through other sources. ADer examination of the meta-analyses. titles and abstracts of these references, we discarded all but 33 with no further assessment. We obtained full-text copies of these Presentation of main results potentially relevant studies and we excluded 16 of them at this We produced 'Summary of findings' tables following GRADE stage (17 references). However, we did not record 14 (15 references) methods (GRADE 2004), and using GRADEPro soDware. We assessed of these in the table of excluded studies, as they were clearly not the quality of the body of evidence by considering the overall risk eligible upon examining the full text. We linked two of the remaining of bias of the included studies, the directness of the evidence, the 16 articles together under a single study reference. Therefore, 15 inconsistency of the results, the precision of the estimates and the studies met the inclusion criteria for this review. This process is risk of publication bias. We categorised the quality of the body of presented as a flow chart in Figure 1.

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Figure 1. Study flow diagram.

Included studies All studies, by necessity, were of parallel design. Nine studies (Asanza 1997, USA; Garib 2005, Brazil; Kilic 2008, Turkey; Lagravere Characteristics of the trial design and setting 2010, Canada; Lippold 2013, Germany; Martina 2012, Italy; Mossaz- FiDeen studies met the inclusion criteria and were included in this Joelson 1989, Switzerland; Oshagh 2012, Iran; Ramoglu 2010, review (see Characteristics of included studies tables). Turkey) were carried out in university orthodontics departments. Orthodontic treatment for posterior crossbites (Review) 12 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

One of these studies stated that the clinicians were two specialist See Appendix 1 for a description of appliances. orthodontists (Lippold 2013), but in the remaining eight studies it was unclear who the clinicians undertaking the treatment 1. Fixed appliance with mid-palatal expansion were and what experience or qualifications they had. There Rapid expansion were three multicentre studies: one was carried out in a general hospital and a university dental hospital in the UK by experienced • Banded Hyrax (tooth borne) versus bonded Hyrax (tooth/tissue orthodontists (McNally 2005); one was carried out in two public borne) (Asanza 1997; Kilic 2008). dental health service clinics and one university orthodontic • Tooth-tissue borne Haas versus tooth borne Hyrax (Garib 2005; department in Sweden by experienced general practitioners under Oliveira 2004). the supervision of specialist orthodontists (Petrén 2008); and • Hyrax tooth-borne expander versus bone-anchored expander one study was carried out in three university orthodontic clinics (Lagravere 2010). and one private practice in Brazil, but it was unclear who the • Four-point banded (Hyrax) versus two-point banded (Hyrax) clinicians undertaking the treatment were and what experience or (Lamparski 2003). qualifications they had (Oliveira 2004). One study took place in a basic dental unit in Brazil, conducted by the local university, with Slow expansion treatment carried out by one specialist orthodontist with over 10 • Bonded Minne versus banded Minne appliances (Mossaz- years of experience (Godoy 2011). Participants in another study Joelson 1989). were treated in a private orthodontic practice in the USA by a board-certified orthodontist with 27 years of experience (Lamparski Di>erent rates of expansion 2003). The remaining study was carried out in Sweden by the public • Slow versus rapid expansion (two-band palatal expanders) dental health service, but the experience of the orthodontist was (Martina 2012). not reported (Thilander 1984). • Semi-rapid versus rapid expansion (splint type tooth- and Characteristics of the participants tissue-borne modified bonded appliances) (Ramoglu 2010).

Seven studies enrolled participants with either a unilateral or 2. Fixed versus removable bilateral crossbite malocclusion (Garib 2005; Martina 2012; McNally 2005; Mossaz-Joelson 1989; O liveira 2004; P etrén 2008; R amoglu Slow expansion 2010), two studies included only participants with a unilateral • Quad-helix versus expansion plate (Godoy 2011; Petrén 2008). crossbite (Godoy 2011; Lippold 2013), two studies included only participants with a bilateral crossbite (Kilic 2008; Oshagh 2012), 3. Other comparisons while the remaining four studies did not specify the type of • Early treatment with fixed bonded Hyrax appliance followed by crossbite that participants presented with at study entry (Asanza U-bow activator therapy versus no treatment (Lippold 2013). 1997; Lagravere 2010; Lamparski 2003; Thilander 1984). • Grinding - occlusal grinding in the primary dentition (aged One study enrolled only children in the permanent dentition (Garib five years old) with/without an upper removable expansion 2005), two studies enrolled only children in the mixed dentition appliance in the mixed dentition versus no treatment (Thilander (Godoy 2011; Petrén 2008), four studies enrolled children in either 1984). the mixed or permanent dentition (Lamparski 2003; Martina 2012; Slow expansion Oliveira 2004; Ramoglu 2010), one study enrolled children in either the late deciduous or early mixed dentition (Lippold 2013), and • Quad-helix plus multi-bracket versus expansion arch plus multi- seven studies did not state the stage of dental development of the bracket (McNally 2005). children at study entry (Asanza 1997; Kilic 2008; Lagravere 2010; • Conventional mid-line expansion screw versus spring-loaded McNally 2005; Mossaz-Joelson 1989; Oshagh 2012; Thilander 1984). expansion screw (Oshagh 2012).

The age range of participants was from five to 16 years old Characteristics of the outcomes with variations between studies, but almost homogeneous within The primary outcome of this review, correction of the posterior individual studies. crossbite, was reported by three studies (Godoy 2011; Petrén 2008; Characteristics of the interventions and comparisons Thilander 1984). In 11 studies, the correction of crossbite is taken for granted because it was the end point of the treatment and the Six of the included studies evaluated two diJerent types of fixed point at which activation of the appliances ceased (Asanza 1997; appliances for rapid palatal expansion (Asanza 1997; Garib 2005; Garib 2005; Kilic 2008; Lagravere 2010; Lamparski 2003; Lippold Kilic 2008; L agravere 2010; Lamparski 2003; O liveira 2004), one 2013; Martina 2012; McNally 2005; Oliveira 2004; Oshagh 2012; study compared two diJerent fixed appliances for slow palatal Ramoglu 2010). In the remaining study, no data were provided on expansion (Mossaz-Joelson 1989), and two studies compared the whether the expansion obtained by these appliances did correct eJects of fixed appliances used for diJering rates of expansion the participants' crossbite (Mossaz-Joelson 1989). (Martina 2012; Ramoglu 2010). All included studies, with the exception of Thilander 1984, reported Two studies compared a fixed appliance with a removable expansion of the upper jaw/teeth measured as changes in the appliance for slow expansion (Godoy 2011; Petrén 2008), and the width between the molars or canines (or both). Two studies remaining studies evaluated other comparisons that were more assessed stability of crossbite correction (Godoy 2011; M ossaz- diJicult to classify (see below) (Lippold 2013; McNally 2005; Oshagh Joelson 1989). 2012; Thilander 1984).

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None of the included studies reported any of the other outcomes of only described as having maxillary deficiency, rather than crossbite this review. (Weissheimer 2011).

Excluded studies Risk of bias in included studies We excluded two studies from this review. One of these studies We have based our assessment of risk of bias on the reports of was excluded because it included a subset of participants from one the included studies because we could not access copies of the of the included studies (Petrén 2008), plus other participants and study protocols. Where the reports were unclear on aspects of the matched controls (Petrén 2011). The other study was excluded aDer methodology, we attempted to contact the study authors to obtain attempting to contact the authors because the participants were clarification or missing information. We present the results of our risk of bias assessment graphically in Figure 2.

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Figure 2. Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

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Allocation Incomplete outcome data Sequence generation We judged eight studies to be at low risk of attrition bias as they either clearly described drop-outs (which were for similar reasons Seven studies described adequate methods of sequence and in similar numbers per group), or the numbers of participants generation and we judged them to be at low risk of bias for stated in the analyses were the same as those randomised, or this domain: three used a table of random numbers (Lagravere an intention-to-treat analysis included all randomised participants 2010; Oliveira 2004; Oshagh 2012); two used block randomisation (Asanza 1997; Godoy 2011; Kilic 2008; Lippold 2013; McNally 2005; (Lippold 2013; Martina 2012); one used a method of drawing lots Oliveira 2004; Petrén 2008; Ramoglu 2010). (Godoy 2011); and the remaining study used a similar method involving opaque sealed envelopes (Petrén 2008). One study clearly described the numbers and reasons for drop-out but the high attrition rate (48% per group) meant that, if the missing One study used random number tables to allocate the first half of participants had higher mean scores in one group than the other, the participants and then allocated the remaining half to receive as the attrition rate increased, so would over/understatement of the alternative treatment to those in the initial allocation (McNally the mean diJerence (Martina 2012). In another study, the attrition 2005). Therefore, only half the participants were truly randomly rate was very diJerent between the treated group (3%) and the allocated and we judged this study to be at high risk of bias for this untreated group (18%) (Thilander 1984). Therefore, we judged domain. these two studies to be at high risk of attrition bias. The remaining seven studies stated only that participants were The remaining five studies did not report whether or not there randomly allocated and we were unable to obtain further details were any drop-outs and it was unclear how many participants were from the authors, so we judged these studies to be at unclear risk of included in the outcome assessment. Therefore, we judged these bias for this domain (Asanza 1997; Garib 2005; Kilic 2008; Lamparski studies to be at unclear risk of attrition bias (Garib 2005; Lagravere 2003; Mossaz-Joelson 1989; Ramoglu 2010; Thilander 1984). 2010; Lamparski 2003; Mossaz-Joelson 1989; Oshagh 2012). Allocation concealment Selective reporting Four studies described adequate methods of allocation Eleven studies reported all outcome measures described in the concealment and we judged them to be at low risk of bias for this corresponding methods sections in full and we assessed them as domain (Godoy 2011; Martina 2012; Oliveira 2004; Petrén 2008). being at low risk of reporting bias (Garib 2005; Godoy 2011; Kilic The method of sequence generation carried out in one study, as 2008; Lagravere 2010; Martina 2012; McNally 2005; Mossaz-Joelson described above, would allow for the prediction of the allocation of 1989; Oliveira 2004; Petrén 2008; Ramoglu 2010; Thilander 1984). half of the participants, and therefore we judged this study to be at We judged the remaining four studies to be at high risk of reporting high risk of bias for this domain (McNally 2005). bias for the following reasons: no measure of variance reported The remaining 10 studies did not mention any method of allocation (Asanza 1997; Lippold 2013); one outcome was not reported by concealment, so we judged these studies to be at unclear risk of group and the other was reported without a measure of variance bias for this domain (Asanza 1997; Garib 2005; Kilic 2008; Lagravere (Lamparski 2003); and the results were so inadequately reported 2010; Lamparski 2003; Lippold 2013; Mossaz-Joelson 1989; Oshagh that we were unable to use any data (Oshagh 2012). 2012; Ramoglu 2010; Thilander 1984). Other potential sources of bias Blinding of outcome assessment (detection bias) In one study, there were imbalances between the treatment groups We did not consider the blinding of participants and personnel in terms of numbers of participants and gender, possibly indicating (performance bias) as the interventions being compared in all a problem with the randomisation (Oshagh 2012). We assessed this studies were diJerent and it would not have been possible to blind study as being at high risk of bias for this domain. We did not them as to which group they were allocated. Therefore, a risk of identify any other potential sources of bias in any of the remaining performance bias is possible in all of the included studies. 14 studies and, therefore, we judged them to be at low risk of bias for this domain. However, it would have been possible for an independent blinded person to perform the clinical, model and radiographic Overall risk of bias assessments. Therefore, we have focused on whether the included • Two studies were at low risk of bias (Godoy 2011; Petrén 2008). studies minimised the possible eJects of detection bias. • Seven studies were at high risk of bias (Asanza 1997; Lamparski Three studies clearly stated that the measurement of outcomes was 2003; Lippold 2013; Martina 2012; McNally 2005; Oshagh 2012; blinded, so we judged these studies to be at low risk of detection Thilander 1984). bias (Godoy 2011; Martina 2012; Petrén 2008). • Six studies were at unclear risk of bias (Garib 2005; Kilic 2008; Lagravere 2010; Mossaz-Joelson 1989; Oliveira 2004; Ramoglu The remaining 12 studies did not mention blinding, even though it 2010). was feasible that it could have occurred, and, therefore, we judged these studies to be at unclear risk of bias for this domain. E>ects of interventions See: Summary of findings for the main comparison Fixed appliances compared with other fixed appliances for treating posterior crossbites; Summary of findings 2 Fixed appliances

Orthodontic treatment for posterior crossbites (Review) 16 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews compared with removable appliances for treating posterior No other outcomes of the review were assessed in this comparison. crossbites; Summary of findings 3 Other comparisons for treating posterior crossbites Di%erent rates of expansion Slow versus rapid expansion (two-band palatal expanders) See Appendix 1 for a description of appliances. One study at high risk of bias, analysing 26 participants, assessed 1. Fixed appliance with mid-palatal expansion molar expansion seven months aDer the start of treatment (Martina Rapid expansion 2012). There was no statistically significant diJerence (Additional Table 1). Banded Hyrax (tooth borne) versus bonded Hyrax (tooth/tissue borne) No other outcomes of the review were assessed in this comparison. We included two studies, one at unclear and one at high risk of bias, analysing 53 participants, in this comparison (Asanza 1997; Semi-rapid versus rapid expansion (splint type tooth- and tissue- Kilic 2008). Due to problems with reporting of the data in one study borne modified bonded appliances) (Asanza 1997), we were unable to combine the results in a meta- One study at unclear risk of bias, analysing 35 participants, analysis. Both studies assessed molar expansion and reported no assessed molar and canine expansion (Ramoglu 2010). There statistically significant diJerence (Table 1). One study measured the were no statistically significant diJerences for either outcome outcomes three months aDer completion of the expansion phase (Additional Table 1). (Asanza 1997), while the other study measured it one week aDer completion of the expansion phase (Kilic 2008). No other outcomes of the review were assessed in this comparison.

No other outcomes of the review were assessed in this comparison. 2. Fixed versus removable Tooth-tissue borne Haas versus tooth borne Hyrax Slow expansion Two studies, both at unclear risk of bias, analysing 27 participants, Quad-helix versus expansion plate assessed molar expansion (Garib 2005; Oliveira 2004). The pooled mean diJerence (MD) was 0.7 mm (95% confidence interval (CI) We included two studies, both at low risk of bias, analysing 96 -0.25 to 1.66) in favour of Haas appliances at three months aDer participants, in this comparison (Godoy 2011; Petrén 2008). The two completion of the expansion phase, but the diJerence was not studies included children in the early mixed dentition (aged eight statistically significant (Analysis 1.1). As the sample size was so to 10 years). For the outcome crossbite correction, the pooled risk ratio (RR) suggests that fixed quad-helix appliances may be 20% small, and there was considerable heterogeneity (I2 = 94%), this more likely to correct crossbites than removable expansion plates result should be interpreted with caution. (RR 1.20; 95% CI 1.04 to 1.37) (Analysis 2.1). The 95% CI indicates No other outcomes of the review were assessed in this comparison. that the true eJect estimate lies somewhere between a 4% and 37% better correction rate for quad-helix appliances. However, the Hyrax tooth-borne expander versus bone-anchored expander sample size was small and there was substantial heterogeneity (I2 One study at unclear risk of bias, analysing no more than 41 = 68%), so this result should be interpreted with caution, and the participants (unclear attrition), assessed molar expansion at six results may not be the same in the permanent dentition. and 12 months aDer completion of the expansion phase (Lagravere For the outcome molar expansion, the pooled MD suggests that 2010). There were no statistically significant diJerences at either quad-helix appliances can achieve 1.15 mm more expansion than time point (Additional Table 1). expansion plates (MD 1.15 mm; 95% CI 0.40 to 1.90) (Analysis 2.2). No other outcomes of the review were assessed in this comparison. The 95% CI indicates that the true eJect estimate lies somewhere between 0.4 mm and 1.9 mm in favour of quad-helix appliances. Four-point banded (Hyrax) versus two-point banded (Hyrax) While there was no heterogeneity (I2 = 0%), the result should be interpreted with caution as the sample size was small and the One study at high risk of bias, analysing no more than follow-up times diJered between the studies. 30 participants (unclear attrition), assessed molar and canine expansion at three months aDer completion of the expansion phase For the outcome canine expansion, the pooled MD was 0.19 mm (Lamparski 2003). There were no statistically significant diJerences (95% CI -0.47 to 0.85) in favour of quad-helix appliances, but for either outcome (Additional Table 1). the diJerence was not statistically significant (Analysis 2.3). Due 2 No other outcomes of the review were assessed in this comparison. to considerable heterogeneity (I = 91%), small sample size and diJerent follow-up times, the result should be interpreted with Slow expansion caution. Bonded Minne versus banded Minne appliances One study also assessed the stability of crossbite correction One study at unclear risk of bias, analysing no more than (relapse 12 months aDer correction) (Godoy 2011). There was no 10 participants (unclear attrition), assessed molar and canine statistically significant diJerence (Additional Table 2). expansion seven to 15 weeks aDer the start of treatment, and No other outcomes of the review were assessed in this comparison. stability (relapse of molar and canine expansion) 24 weeks aDer completion of the expansion phase (Mossaz-Joelson 1989). One study also compared both appliances in this comparison There were no statistically significant diJerences for any outcome against composite onlays (Petrén 2008). There were statistically (Additional Table 1). significant diJerences for the outcomes crossbite correction, molar

Orthodontic treatment for posterior crossbites (Review) 17 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews expansion and canine expansion in favour of the fixed and Fixed versus removable appliance removable appliances (Additional Table 2). We found low-quality evidence to suggest that crossbite correction 3. Other comparisons is more successful when using a fixed quad-helix appliance than when using a removable expansion plate for slow maxillary Early treatment with fixed bonded Hyrax appliance followed by expansion (Summary of findings 2). For the same comparison, U-bow activator therapy versus no treatment moderate-quality evidence suggested that molar expansion is One study at high risk of bias, analysing 66 participants, assessed greater for fixed quad-helix appliances, and further low-quality molar and canine expansion 12 months aDer the start of treatment evidence was insuJicient to determine a diJerence in canine (Lippold 2013). Statistically significant diJerences were reported expansion. It should be noted that the two studies included for both outcomes in favour of treatment (Additional Table 3). children in the early mixed dentition (aged eight to 10 years) and the results may not be the same for people in the permanent No other outcomes of the review were assessed in this comparison. dentition. There was also very low quality evidence that was insuJicient to determine a diJerence in stability of crossbite Grinding - occlusal grinding in the primary dentition (at age five correction between fixed quad-helix appliances and removable years) with/without subsequent upper removable expansion expansion plates. Further very low quality evidence suggested appliance in the mixed dentition versus no treatment that fixed quad-helix appliances and removable expansion plates One study at high risk of bias, analysing 61 participants, assessed are superior to composite onlays for crossbite correction, molar crossbite correction aDer one, two, five and eight years (Thilander expansion and canine expansion. 1984). A statistically significant diJerence was reported in favour of Others interventions treatment (Additional Table 3). We found very low quality evidence to suggest that both tooth Slow expansion grinding, with or without an expansion plate and fixed bonded Quad-helix plus multi-bracket versus expansion arch plus multi- Hyrax followed by U-bow activator are superior to no treatment bracket for the outcomes crossbite correction and molar/canine correction respectively (Summary of findings 3). We also found very low One study at high risk of bias assessed molar (analysing 55 quality evidence that was insuJicient to determine a diJerence participants) and canine (analysing 52 participants - lower number in molar or canine expansion between quad-helix plus multi- due to unerupted canines) expansion 12 weeks aDer the start of bracket and expansion arch plus multi-bracket. Finally, there was treatment (McNally 2005). There were no statistically significant no evidence regarding the comparison of removable appliances diJerences for either outcome (Additional Table 3). with either spring-loaded or conventional screws.

Conventional mid-line expansion screw versus spring-loaded Overall completeness and applicability of evidence expansion screw One study at high risk of bias assessed molar and canine expansion The studies identified in this review are insuJicient to address the but we were unable to extract any data from the study report question of what is the best treatment for posterior crossbites. (Oshagh 2012). Although we were able to include 15 studies, there were many diJerent comparisons of appliances or other treatments and, D I S C U S S I O N therefore, there was minimal pooling of data. This is unfortunate as one of the advantages of a systematic review is the ability to Summary of main results pool multiple studies in order to increase the power to detect a diJerence confidently, and thus to inform clinical practice The objective of this review was to evaluate the eJects of diJerent better. Furthermore, there were very limited data available for the orthodontic treatments for correcting posterior crossbites. We outcome stability of crossbite correction, and no studies assessed included 15 randomised controlled trials (RCTs) that met the signs and symptoms of temporomandibular joint dysfunction/ inclusion criteria for this review. We assessed the body of evidence respiratory disease or quality of life. However, this was perhaps for each comparison and outcome using GRADE, which takes into because all the studies included only children. This highlights account the risk of bias of the included studies, the directness of another shortcoming in the overall completeness of the evidence, the evidence, the inconsistency of the results, the precision of the which is that there is no evidence on orthodontic treatments for estimates and the risk of publication bias (GRADE 2004). The body adults with posterior crossbites. The lack of evidence regarding of evidence for all comparisons and outcomes in this review was adults in this review is probably because the majority of studies on very small. adults with a posterior crossbite compare orthodontic treatments with orthodontic-surgical interventions, but we excluded surgical Fixed appliance with mid-palatal expansion treatments from this review. The body of evidence for all comparisons and outcomes in this group was rated as very low quality (Summary of findings for the Quality of the evidence main comparison). In all cases, the evidence was insuJicient to The body of evidence identified does not allow for any robust determine a diJerence between any one type of appliance and conclusions to be made regarding the objective of this review. The another for any outcome. sample sizes were consistently small (as low as eight participants), and this fact, combined with the lack of pooling of data in meta- analyses, meant that the power to detect statistically and clinically significant diJerences, with confidence, was limited. Another

Orthodontic treatment for posterior crossbites (Review) 18 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews problem was inconsistency as three of the four meta-analyses than removable expansion plates at correcting posterior crossbites displayed statistically significant heterogeneity. While there were and expanding the inter-molar width in children with early mixed two low risk of bias studies that we were able to pool, the results dentition (aged eight to 10 years). The remaining evidence that we cannot be relied upon due to the problems already mentioned. The found was of very low quality and was insuJicient to allow the remaining studies were either at high risk of bias (seven studies) or conclusion that any one intervention is better than another for any the risk of bias was unclear (six studies). Most of the comparisons of the outcomes in this review. included in the review were assessed by very small single studies, which do not allow any conclusions to be drawn as to the eJects of Implications for research the interventions studied. More randomised controlled trials are required to address the Potential biases in the review process question of what is the best treatment for posterior crossbites in children, adolescents and adults. The studies should be large We made every attempt to limit bias in the review process by enough to detect a diJerence, if one exists, and should assess ensuring a comprehensive search for potentially eligible studies. appropriate outcomes. We believe that 'correction of crossbite' The authors' independent assessments of study eligibility and needs to be the primary outcome for all studies addressing subsequent data extraction and risk of bias assessment minimised this research question. In studies where all the crossbites were the potential for additional bias beyond that detailed in the 'Risk of corrected (as with most studies in this review), 'time to correction' bias' tables in the Characteristics of included studies section. The and 'pain' would be of increased importance as outcomes. incompleteness of some of the reports and our inability to obtain clarification of certain trial details or to resolve ambiguities in the High-quality work should be carried out to develop core outcome reports may have contributed to some bias in their assessment, sets for orthodontics/areas of orthodontics. Such work should be but where these conditions applied this was explicitly stated in the carried out in association with the COMET (Core Outcome Measures text of our review. Finally, we attempted to minimise bias further in EJectiveness Trials) Initiative (www.comet-initiative.org), using by changing our inclusion criteria to only include RCTs which, when robust methodology suggested by those working with the COMET performed to a high standard, should be less biased than other Initiative so far (Williamson 2012). These core outcome sets should study designs. subsequently be the minimum set of outcomes that are measured in all clinical trials and systematic reviews (including this Cochrane Agreements and disagreements with other studies or review). reviews Future randomised controlled trials must be well designed, Another systematic review of maxillary expansion arches for well conducted and adequately delivered with subsequent treating crossbites included studies published from 1999 to 2011 reporting, including high-quality descriptions of all aspects of (Zuccati 2013). The authors of the review assessed the studies methodology. Reporting should conform to the Consolidated using the Consolidated Standards of Reporting Trials (CONSORT) Standards of Reporting Trials (CONSORT) statement (www.consort- statement. In similarity with our review, they argued that there statement.org), which will enable appraisal and interpretation was substantial evidence of bias, which reduced the quality of the of results, and accurate judgements to be made about the risk evidence; the randomisation process was poorly described and loss of bias and the overall quality of the evidence. Although it is to follow-up was unclear in many of the included studies. Their uncertain whether reported quality mirrors actual study conduct, review also called for future trials to be carefully planned and it is noteworthy that studies with unclear methodology have been reported using universal guidelines. shown to produce biased estimates of treatment eJects (Schulz 1995). A U T H O R S ' C O N C L U S I O N S A C K N O W L E D G E M E N T S Implications for practice The review authors would like to thank the Cochrane Oral Health There is a very small body of low- to moderate-quality evidence to Group and referees for their help in conducting this systematic suggest that fixed quad-helix appliances may be more successful review.

Orthodontic treatment for posterior crossbites (Review) 19 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

REFERENCES

References to studies included in this review Oliveira 2004 {published data only} Asanza 1997 {published data only} Ghandehari B. A Comparison of the Skeletal EJects of Toothborne and Tissue-Borne Rapid Palatal Expanders [thesis]. Asanza S. Comparison of Hyrax and bonded expansion Chicago: University of Illinois at Chicago, 2001. appliances. The Angle Orthodontist 1997;67(1):15-22. * Oliveira NL, Da Silveira AC, Kusnoto B, Viana G. Three- Garib 2005 {published data only} dimensional assessment of morphologic changes of the Garib DG, Henriques JF, Janson G, Freitas MR, Coelho RA. maxilla: a comparison of 2 kinds of palatal expanders. Rapid maxillary expansion - tooth tissue-borne versus tooth- American Journal of Orthodontics and Dentofacial Orthopedics borne expanders: a computed tomography evaluation of 2004;126(3):354-62. dentoskeletal eJects. The Angle Orthodontist 2005;75(4):548-57. Oshagh 2012 {published data only} Godoy 2011 {published and unpublished data} Oshagh M, Momeni Danaei Sh, Hematiyan MR, Hajian Kh, Godoy F, Godoy-Bezerra J, Rosenblatt A. Treatment of posterior Shokoohi Z. Comparison of dental arch changes and patients' crossbite comparing 2 appliances: a community-based trial. discomforts between newly designed maxillary expansion American Journal of Orthodontics and Dentofacial Orthopedics screw and slow expansion procedures. Journal of Dentistry, 2011;139:e45-52. Shiraz University of Medical Sciences 2012;13(3):110-9.

Kilic 2008 {published data only} Petrén 2008 {published data only} Kilic N, Kiki A, Oktay H. A comparison of dentoalveolar Petrén S, Bondemark L. Correction of unilateral posterior inclination treated by two palatal expanders. European Journal crossbite in the mixed dentition: a randomized controlled trial. of Orthodontics 2008;30(1):67-72. American Journal of Orthodontics and Dentofacial Orthopedics 2008;133:790.e7-13. Lagravere 2010 {published and unpublished data} Lagravere MO, Carey J, Heo G, Toogood RW, Major PW. Ramoglu 2010 {published data only} Transverse, vertical, and anteroposterior changes from bone- Ramoglu SI, Sari Z. Maxillary expansion in the mixed dentition: anchored maxillary expansion vs traditional rapid maxillary rapid or semi-rapid?. European Journal of Orthodontics expansion: a randomized clinical trial. American Journal of 2010;32:11-8. Orthodontics and Dentofacial Orthopedics 2010;137(3):304. Thilander 1984 {published data only} Lamparski 2003 {published data only} Thilander B, Wahlund S, Lennartsson B. The eJect of early Lamparski DG Jr, Rinchuse DJ, Close JM, Sciote JJ. Comparison interceptive treatment in children with posterior cross-bite. of skeletal and dental changes between 2-point and 4-point European Journal of Orthodontics 1984;6:25-34. rapid palatal expanders. American Journal of Orthodontics and Dentofacial Orthopedics 2003;123(3):321-8. References to studies excluded from this review Lippold 2013 {published data only} Petrén 2011 {published and unpublished data} Lippold C, Stamm T, Meyer U, Végh A, Moiseenko T, Danesh G. Early treatment of posterior crossbite - a randomised clinical Petrén S, Bjerklin K, Bondemark L. Stability of unilateral trial. Trials 2013;14:20. posterior crossbite correction in the mixed dentition: a randomised clinical trial with a 3-year follow-up. American Martina 2012 {published data only} Journal of Orthodontics and Dentofacial Orthopedics Martina R, CioJi I, Farella M, Leone P, Manzo P, Matarese G, et 2011;139:e73-81. al. Transverse changes determined by rapid and slow maxillary Weissheimer 2011 {published data only} expansion. A low-dose CT-based randomised controlled trial. Orthodontics & Craniofacial Research 2012;15:159-68. Weissheimer A, de Menezes LM, Mezomo M, Dias DM, de Lima EM, Rizzatto SM. Immediate eJects of rapid maxillary McNally 2005 {published and unpublished data} expansion with Haas-type and hyrax-type expanders: a McNally MR, Spary DJ, Rock WP. Randomized controlled randomized clinical trial. American Journal of Orthodontics and trial comparing the quadhelix and the expansion arch Dentofacial Orthopedics 2011;140(3):366-76. for the correction of crossbite. Journal of Orthodontics

2005;32(1):29-35. Additional references Mossaz-Joelson 1989 {published and unpublished data} Bresolin 1983 Mossaz-Joelson K, Mossaz C. Slow maxillary expansion: a Bresolin D, Shapiro PA, Shapiro GG, Chapko MK, Dassel S. Mouth comparison between bonded and banded appliances. European breathing in allergic children: its relationship to dentofacial Journal of Orthodontics 1989;11:67-76. development. American Journal of Orthodontics 1983;83:334-40.

Orthodontic treatment for posterior crossbites (Review) 20 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Cheng 1988 Lindner 1989 Cheng M-C, Enlow DH, Papsidero M, Broardbent BH, Oyen O, Lindner A. Longitudinal study on the eJect of early interceptive Sabat, M. Developmental eJects of impaired breathing treatment in 4-year-old children with unilateral cross-bite. in the face of the growing child. The Angle Orthodontist Scandinavian Journal of Dental Research 1989; Vol. 97, issue 1988;58:309-20. 5:432-8.

Egermark 1990 Malandris 2004 Egermark-Eriksson I, Carlsson GE, Magnusson T, Thilander B. Malandris M, Mahoney EK. Aetiology, diagnosis and treatment A longitudinal study on malocclusion in relation to signs and of posterior cross-bites in the primary dentition. International symptoms of cranio-mandibular disorders in children and Journal of Paediatric Dentistry 2004; Vol. 14, issue 3:155-66. adolescents. European Journal of Orthodontics 1990;12:399-407. McNamara 1997 Egger 1997 McNamara JA Jr, Turp JC. Orthodontic treatment and Egger M, Davey Smith G, Schneider M, Minder C. Bias in temporomandibular disorders: is there a relationship?. Journal meta-analysis detected by a simple, graphical test. BMJ of Orofacial Orthopedics 1997;58:74-89. 1997;315(7109):629-34. Modeer 1982 Gesch 2004 Modeer T, Odenrick L, Lindner A. Sucking habits and their Gesch D, Bernhardt O, Kirbschus A. Association of malocclusion relationship to posterior crossbites in 4-year-old children. and functional occlusion with temporomandibular disorders Scandinavian Journal of Dental Research 1982;90:323-8. (TMD) in adults: a systematic review of population-based studies. Quintessence International 2004;35(3):211-21. Ninou 1994 Ninou S, Stephens C. The early treatment of posterior GRADE 2004 crossbites: a review of continuing controversies. Dental Update GRADE Working Group. Grading quality of evidence and 1994;21:420-6. strength of recommendations. BMJ 2004;328(7454):1490. O'Bryn 1995 Heikinheimo 1987 O'Bryn BL, Sadowsky C, Schneider B, BeGole EA. An evaluation Heikinheimo K, Salmi K, Myllarniemi S. Long term evaluation of mandibular asymmetry in adults with unilateral posterior of orthodontic diagnosis made at the ages of 7 and 10 years. crossbite. American Journal of Orthodontics and Dentofacial European Journal of Orthodontics 1987;9:151-9. Orthopedics 1995;107:394-400.

Higgins 2011 Ogaard 1994 Higgins JPT, Green S (editors). Cochrane Handbook for Ogaard B, Larsson E, Lindsten R. The eJects of sucking habits, Systematic Reviews of Interventions Version 5.1.0 [updated cohort, sex, intercanine arch widths, and breast or bottle March 2011]. The Cochrane Collaboration, 2011. Available from feeding on posterior crossbite in Norwegian and Swedish www.cochrane-handbook.org. 3-year-old children. American Journal of Orthodontics and Dentofacial Orthopedics 1994;106:161-6. Iodice 2013 Iodice G, Danzi G, Cimino R, Paduano S, Michelotti A. Pullinger 1993 Association between posterior crossbite, masticatory muscle Pullinger AG, Seligman DA, Gornbein JA. A multiple pain, and disc displacement: a systematic review. European logistic regression analysis of the risk and relative odds of Journal of Orthodontics 2013;35(6):737-44. temperomandibular disorders as a function of common occlusal factors. Journal of Dental Research 1993;72:968-79. Kennedy 2005 Kennedy DB, Osepchook M. Unilateral posterior crossbite with Schulz 1995 mandibular shiD: a review. Journal of the Canadian Dental Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence Association 2005;71(8):569-73. of bias. Dimensions of methodological quality associated with estimates of treatment eJects in controlled trials. JAMA Kurol 1992 1995;273(5):408-12. Kurol J, Berglund L. Longitudinal and cost-benefit analysis of the eJect of early treatment of posterior cross-bites in Subtelny 1980 the primary dentition. European Journal of Orthodontics Subtelny JD. Oral respiration: facial maldevelopment and 1992;14:173-9. corrective dentofacial orthopedics. The Angle Orthodontist 1980;50:147-64. Leighton 1966 Leighton BC. The early development of cross-bites. Dental Thilander 2002 Practitioner 1966;17:145-52. Thilander B, Rubio G, Pena L, de Mayorga C. Prevalence of temporomandibular dysfunction and its association with malocclusion in children and adolescents: an epidemiologic

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study related to specified stages of dental development. The Zuccati 2013 Angle Orthodontist 2002;72(2):146-54. Zuccati G, Casci S, Doldo T, Clauser C. Expansion of maxillary arches with crossbite: a systematic review of RCTs in the last 12 Thilander 2012 years. European Journal of Orthodontics 2013;35(1):29-37. Thilander B, Bjerklin K. Posterior crossbite and temporomandibular disorders (TMDs): need for orthodontic treatment?. European Journal of Orthodontics References to other published versions of this review 2012;34(6):667-73. Harrison 2001 Williamson 2012 Harrison JE, Ashby D. Orthodontic treatment for posterior Williamson PR, Altman DG, Blazeby JM, Clarke M, Devane D, crossbites. Cochrane Database of Systematic Reviews 2001, Issue Gargon E, et al. Developing core outcome sets for clinical trials: 1. [DOI: 10.1002/14651858.CD000979] issues to consider. Trials 2012;13:132.

* Indicates the major publication for the study

C H A R A C T E R I S T I C S O F S T U D I E S

Characteristics of included studies [ordered by study ID]

Asanza 1997 Methods Study design: RCT (2 arms)

Location: Orthodontics Department, Albert Einstein College of Medicine and Montefiore Medical Cen- ter, New York, USA

Number of centres: 1

Recruitment period: Not stated

Funding source: Not stated but study part of a Master's thesis

Clinician experience: Not stated

Participants Inclusion criteria: Children with posterior crossbites

Exclusion criteria: None stated

Age: 8.5 to 16 years

Gender: M/F 7/7

Number randomised: 14 (Gp A: 7; Gp B: 7)

Number evaluated: 14 (Gp A: 7; Gp B: 7)

Interventions Comparison: (Fixed appliances) (rapid expansion) banded Hyrax (tooth borne) versus bonded Hyrax (tooth/tissue borne)

Gp A (n = 7): Conventional Hyrax expander with mid-palatal jackscrew assembly and 4 rigid steel wires that were soldered to the bands on abutment teeth usually first premolars and first molars

Gp B (n = 7): Same Hyrax expander jackscrew assembly as Gp A but wires were soldered to 0.036 wire loops bent circumferentially at the height of contour of the abutment teeth. The acrylic portion en- cased the occlusal, lingual and buccal surfaces of the abutment teeth

Participants in both groups were instructed to turn screw twice per day (0.5 mm). After expansion, appliances remained for a 3-month retention phase

Outcomes Lateral and posterior-anterior cephalometric assessment of angular and linear skeletal and dental changes Molar expansion

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Asanza 1997 (Continued) Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk Quote: "Appliances were randomly assigned" tion (selection bias) Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk Quote: "Appliances were randomly assigned" (selection bias) Comment: Not mentioned

Blinding of outcome as- Unclear risk Not mentioned sessment (detection bias) All outcomes

Incomplete outcome data Low risk No drop-outs reported. Data in Table 5 implied that there were no drop-outs (attrition bias) All outcomes

Selective reporting (re- High risk No measures of variance were reported, so we were unable to analyse the data porting bias)

Other bias Low risk No other sources of bias identified

Garib 2005 Methods Study design: RCT (2 arms)

Location: Orthodontics Department, Bauru School of Dentistry, University of Sao Paulo, Brazil

Number of centres: 1

Recruitment period: Not stated

Funding source: Not stated

Clinician experience: Not stated

Participants Inclusion criteria: Females presenting with Class I or Class II malocclusion with unilateral or bilateral crossbite

Exclusion criteria: age below 11 and above 14 years, persistence of any primary tooth, absence of maxillary posterior permanent teeth, metallic restorations on the maxillary posterior teeth, previous periodontal disease, previous orthodontic treatment and M sex

Age: Gp A: mean 12.4 years (range 11.4-13.6); Gp B: mean 12.6 years (range 11.5-13.9)

Gender: 100% F

Number randomised: 8 (Gp A: 4; Gp B: 4)

Number evaluated: Not stated

Interventions Comparison: (Fixed appliances) (rapid expansion) tooth-tissue borne Haas versus tooth borne Hyrax

Orthodontic treatment for posterior crossbites (Review) 23 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Garib 2005 (Continued) Gp A (n = 4): Tooth-tissue borne palatal acrylic Haas type expander

Gp B (n = 4): Tooth-borne Hyrax expander (no palatal acrylic)

Both groups had the screw activated by a complete turn after placement, followed by a one-quarter turn morning and evening of each day (0.5 mm/day) until full expansion on day 16 (total of 7 mm expansion). Appliance was then kept as a retainer for a further 3 months and then removed, at which point the outcomes were measured

Outcomes Transverse maxillary expansion

Maxillary posterior teeth axial inclination

Notes Casual and systematic errors were calculated comparing the first measurement with Dahlberg's formu- la and second measurement with dependent t-test at a significance level of 5%

No sample size calculation reported, but authors suggest that study is probably underpowered

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk Quote: "...sample of eight patients, who were randomly assigned to two tion (selection bias) groups"

Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk Quote: "...sample of eight patients, who were randomly assigned to two (selection bias) groups"

Comment: Not mentioned

Blinding of outcome as- Unclear risk It appears that it would have been possible to blind outcome assessors as the sessment (detection bias) appliances were removed before final measurements were made. However, it All outcomes was not mentioned

Incomplete outcome data Unclear risk No indication of whether or not there were any drop-outs. Unclear how many (attrition bias) participants were included in the outcome assessment All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Godoy 2011 Methods Study design: RCT (3 arms)

Location: Dental clinic of Santo Amaro by the University of Pernambuco, Brazil

Number of centres: 1

Recruitment period: Not stated

Funding source: University of Pernambuco and research grant from the Ministry of Education of Brazil (CAPES)

Clinician experience: Specialist orthodontist with over 10 years of experience

Orthodontic treatment for posterior crossbites (Review) 24 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Godoy 2011 (Continued) Participants Inclusion criteria: Children had both unilateral posterior dental and functional crossbites in the mixed dentition; all had skeletal posterior crossbite diagnosed by examining the casts, models and anterio- posterior cephalometric radiographs

Exclusion criteria: Sucking habits, previous orthodontic treatment, Class III malocclusion

Gp A: mean age 8.00 years (SD 0.79); M/F 7/26

Gp B: mean age 7.82 years (SD 0.85); M/F 15/18

Gp C: mean age 8.09 years (SD 0.81); M/F 19/14

Number randomised: 99 (Gp A: 33; Gp B: 33; Gp C: 33)

Number evaluated: 99 (Gp A: 33; Gp B: 33; Gp C: 33)

Interventions Comparison: (Fixed versus removable appliances) (slow expansion) quad-helix versus expansion plate versus untreated control group

Gp A (n = 33): Quad-helix fixed appliance with stainless steel bands bonded to teeth (tooth borne). Ap- pliance was activated once a month until crossbite was corrected

Gp B (n = 33): Expansion plate removable appliance with mid-line screw and acrylic covering (tooth-tissue borne). Appliance worn day and night and removed for teeth brushing. Appliance was activated a one-quarter rotation of the screw once a week (0.25 mm)

Gp C (n = 33): No treatment

Gps A and B were evaluated every 4 weeks, no overcorrection was produced and once correction was achieved each child had a retention plate to be used 24 hours/day for 3 months and then only at night for a further 3 months

Outcomes Correction of crossbite

Maxillary and mandibular inter-molar and inter-canine expansion

Length of treatment

Cost-benefit

Success rate (stability)

Number of complications

(Evaluation after crossbite correction, after 6-month retention, after retention removal)

Notes "The sample size calculation established an error of 5% and a power of 95%. To detect any differences in length of treatment between the 2 methods, the means and standard deviations were calculated based on the data from the study of Hermanson et al (8.00 ± 3.00 for the QH [quad-helix]; 12.00 ± 5.00 for the EP [expansion plate]). The sample should include 27 patients per group to show a statistically significant difference"

Email sent to authors 22 November 2012, reply received 23 November 2012

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "For randomization, numbers were randomly drawn from a plastic bag. tion (selection bias) Each child received a number from 1 to 99"

From email correspondence: "Each child received a number according to the clinical examination order. When all 99 children had a number, a helper took

Orthodontic treatment for posterior crossbites (Review) 25 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Godoy 2011 (Continued) the 99 pieces of papers numbering from 1 to 99 from the bag. The first number to be taken would belong to QDH [quad-helix] group, the second one to the EP [expansion plate] group, the third one to the untreated group, the fourth to the QDH group..."

Allocation concealment Low risk The method described above would not allow anybody involved in the study (selection bias) to know their treatment allocation until they had been allocated

Blinding of outcome as- Low risk Quote: "Palatal expansion and crossbite correction were measured on the sessment (detection bias) study casts by 1 masked investigator... The investigator was unaware of the All outcomes type of appliance used by the patient and the length of treatment (pretreat- ment, after expansion, after 6 months of retention, or 6 months after removal of the retention plate)"

Incomplete outcome data Low risk "Dropouts and treatments not completed within 12 months were classified as (attrition bias) unsuccessful" All outcomes Intention-to-treat analysis included all randomised participants

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Kilic 2008 Methods Study design: RCT (2 arms)

Location: Department of Orthodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey

Number of centres: 1

Recruitment period: Not stated

Funding source: Not stated

Clinician experience: Not stated

Participants Inclusion criteria: Participants with severe maxillary arch width deficiency, bilateral crossbite and deep palatal vault

Exclusion criteria: People with mucosal swelling during maxillary expansion

Age: Gp A: 13.75 years (SD 17 months); Gp B: 13.5 years (SD 12 months)

Gender: M/F 10/29

Number randomised: 39 (Gp A: 21; Gp B: 18)

Number evaluated: 39 (Gp A: 21; Gp B: 18)

Interventions Comparison: (Fixed appliances) (rapid expansion) banded Hyrax (tooth borne) versus bonded Hyrax (tooth/tissue borne)

Gp A (n = 21): Conventional Hyrax tooth-borne appliance for rapid maxillary expansion

Gp B (n = 18): Acrylic bonded appliance for rapid maxillary expansion

Appliances were activated twice a day, one-quarter turn each time (0.5 mm/day)

Orthodontic treatment for posterior crossbites (Review) 26 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Kilic 2008 (Continued) Outcomes Maxillary molar expansion

Molar crown tipping

Alveolar inclination

Notes No sample size calculation reported

Email sent 22 November 2012

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk Quote: "Randomly assigned to two groups" tion (selection bias) Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk Quote: "Randomly assigned to two groups" (selection bias) Comment: Not mentioned

Blinding of outcome as- Unclear risk It may have been possible to blind outcome assessors if the appliances were sessment (detection bias) removed before final measurements were made. However, this was not men- All outcomes tioned

Incomplete outcome data Low risk No drop-outs reported. Numbers of participants per group reported in the re- (attrition bias) sults tables matches the numbers that were randomised All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Lagravere 2010 Methods Study design: RCT (3 arms)

Location: Orthodontic clinic at the University of Alberta in Edmonton, Alberta, Canada

Number of centres: 1

Recruitment period: 18-month recruitment period

Funding source: Not stated

Clinician experience: Not stated

Participants Inclusion criteria: People needing maxillary expansion with posterior crossbite

Exclusion criteria: None stated

Gp A: mean age 14.05 years (SD 1.35); M/F 5/15

Gp B: mean age 14.24 years (SD 1.32); M/F 8/13

Gp C: mean age 12.86 years (SD 1.19); M/F 6/15

Number randomised: 62 (Gp A: 20; Gp B: 21; Gp C: 21) Orthodontic treatment for posterior crossbites (Review) 27 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Lagravere 2010 (Continued) Number evaluated: Not stated

Interventions Comparison: (Fixed appliances) (rapid expansion) Hyrax tooth-borne expander versus bone-anchored expander versus untreated control group

Gp A (n = 20): Tooth anchored maxillary expander (TAME) Hyrax with bands on the first permanent molars and first premolars. Activated 0.5 mm per day until posterior dental crossbite over correction was achieved

Gp B (n = 21): Bone-anchored maxillary expander (BAME) composed of 2 custom-milled stainless steel onplants, 2 miniscrews and an expansion screw. A healing period of 1 week was allowed before activation of the expander. Activation consisted of 0.25 mm every other day until overcorrection was achieved

Gp C (n = 21): Treatment delayed for 12 months to serve as a control group

In Gps A and B, the appliance was removed after overcorrection was achieved and leD without retention for an additional 6 months

Outcomes Molar expansion

Inclination

Pain

Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "Subjects were randomized into the groups by using a random num- tion (selection bias) bers generated list"

Allocation concealment Unclear risk Quote: "Subjects were randomized into the groups by using a random num- (selection bias) bers generated list"

Comment: Not mentioned

Incomplete outcome data Unclear risk No indication of whether or not there were any drop-outs. Unclear how many (attrition bias) participants were included in the outcome assessment All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Lamparski 2003 Methods Study design: RCT (2 arms)

Location: Private practice, Natrona Heights, PA, USA

Number of centres: 1

Orthodontic treatment for posterior crossbites (Review) 28 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Lamparski 2003 (Continued) Recruitment period: Not stated

Funding source: Not stated

Clinician experience: Board-certified orthodontist with 27 years of experience

Participants Inclusion criteria: Crossbite; mixed or permanent dentition

Exclusion criteria: Systemic disease, dental pathology; maxillary tori

Gp A: mean age 11.33 years (range 7.75-13.92); M/F 9/6

Gp B: mean age 10.8 years (range 6.58-14.58); M/F 6/9

Number randomised: 30 (Gp A: 15; Gp B: 15)

Number evaluated: Not stated

Interventions Comparison: (Fixed appliances) (rapid expansion) 4-point expansion appliance (Hyrax) versus 2- point expansion appliance

Gp A (n = 15): The 4-point expansion appliance consisted of a Hyrax expansion screw with bands ce- mented to the maxillary first permanent molars and either the maxillary first premolars or the maxillary deciduous first molars. Activated 0.5 mm per day until posterior dental crossbite overcorrection was achieved

Gp B (n = 15): The 2-point expander was banded only to the maxillary first permanent molars and had a jackscrew (a typical Hyrax appliance with both anterior wires removed). Activated 0.5 mm per day until posterior dental crossbite overcorrection was achieved

Outcomes Molar, canine and sutural expansion

Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk Quote: "The subjects were randomly assigned" tion (selection bias) Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk Quote: "The subjects were randomly assigned" (selection bias) Comment: Not mentioned

Incomplete outcome data Unclear risk No indication of whether or not there were any drop-outs. Unclear how many (attrition bias) participants were included in the outcome assessment All outcomes

Selective reporting (re- High risk Outcomes planned in the methods section were reported in the results. How- porting bias) ever, means and SDs in each group were not reported

Other bias Low risk No other sources of bias identified

Orthodontic treatment for posterior crossbites (Review) 29 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Lippold 2013 Methods Study design: RCT (2 arms)

Location: Orthodontics Department, Münster University's Medical Sciences Division and University Hospital Münster, Germany

Number of centres: 1

Recruitment period: Not stated

Funding source: Not stated

Clinician experience: "Two specialists in orthodontics"

Participants Inclusion criteria: Functional unilateral posterior crossbite in the late deciduous or early mixed dentition

Exclusion criteria: mid-line deviation during orthodontic treatment; persisting habits; general diseases with permanent medication (e.g. diabetes mellitus); syndromes; cleD lip and palate; general impair- ments; structural orthopaedic diseases

Age: Gp A: mean 7.3 years (SD 2.2); Gp B: mean 7.2 years (SD 2)

Gender: "The gender ratio was nearly equal at the beginning of the study"

Number randomised: 82 (Gp A: 40; Gp B: 42). However, 5 participants dropped out after randomisation but before treatment (Gp A: 37; Gp B: 40)

Number evaluated: 66 (Gp A: 31; Gp B: 35)

Interventions Comparison: (Slow expansion) early treatment with fixed bonded Hyrax appliance followed by U- bow activator therapy versus no treatment

Gp A (n = 37): Bonded Hyrax appliance worn 24 hours per day. Once per day activation (0.2 mm) was mandatory and the maxillary expansion was achieved in a mean of 3.2 weeks (SD 1.2). This was followed by a retention period of a mean of 12.6 weeks (SD 1.8). The U-bow activator was then applied for a mean of 36.8 weeks (SD 5.4). This was a double-plate activator combined with eponymous U-shaped wire bows on each side (protrusive and labial bows on the upper and lower jaws). The maxillary plate had an additional transversal expansion screw for retention of the achieved expansion

Gp B (n = 40): No treatment (after the final follow-up point, these children received the same treatment as those in the therapy group)

Outcomes Sagittal, vertical and transversal dimensions of the maxilla and mandible Mid-line deviation between the anterior teeth of the maxilla and mandible Sagittal overjet and vertical overbite

Outcomes were measured 1 year after the start of treatment

Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "Block randomisation with a block length of 20 and an allocation ratio tion (selection bias) of 1:1"

Allocation concealment Unclear risk Quote: "Block randomisation with a block length of 20 and an allocation ratio (selection bias) of 1:1"

Comment: Not mentioned

Orthodontic treatment for posterior crossbites (Review) 30 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Lippold 2013 (Continued) Blinding of outcome as- Unclear risk It appears that it would have been possible to blind outcome assessors as the sessment (detection bias) appliances could have been removed before final measurements were made. All outcomes In contrast, the children's group may have been obvious due to there being an untreated control group whose crossbites would not be properly corrected. However, it was not mentioned

Incomplete outcome data Low risk Numbers of drop-outs and reasons were clearly described in a study workflow (attrition bias) (Figure 1), and were sufficiently similar in each group All outcomes

Selective reporting (re- High risk No SD for mean change from baseline reported porting bias)

Other bias Low risk No other sources of bias identified

Martina 2012 Methods Study design: RCT (2 arms)

Location: Department of Oral Science, University of Naples Federico II, Italy

Number of centres: 1

Recruitment period: May 2006 to October 2007

Funding source: Grant from the Italian Ministry of University and Research

Clinician experience: Not stated

Participants Inclusion criteria: Children up to 13 years old (M) and 12 years old (F), with erupted permanent first molars and unilateral or bilateral full cusp posterior crossbite

Exclusion criteria: Severe periodontal disease (probing depth > 4 mm), congenital syndromes, defects, previous orthodontic treatment

Gp A: mean age 10.3 years (SD 2.5); M/F 7/5 Gp B: mean age 9.7 years (SD 1.5); M/F 6/8

Number randomised: 50 (Gp A: 23; Gp B: 27). However, 9 children dropped out after randomisation but before treatment (Gp A: 19; Gp B: 22)

Number evaluated: 26 (Gp A: 12; Gp B: 14)

Interventions Comparison: (Fixed appliances) slow versus rapid expansion A 2-band palatal expander was used for both groups

Gp A (n = 12): Slow expansion, the screw was turned twice a week (0.50 mm activation per week)

Gp B (n = 14): Rapid expansion, screw was initially turned 8 times (2.0-mm screw activation) at chair side 2 hours after curing. Thereafter, the children's parents were trained to turn the screw 3 times per day (0.75 mm activation per day)

In both groups, the jackscrew was activated until a 2 mm molar transverse overcorrection was achieved. After the required expansion was achieved, the screw was locked with light-cure flow composite. The appliances were removed 7 months after treatment started, at which point the outcomes were measured

Outcomes Molar expansion at molar cusp

Antero and posterior maxillary expansion Orthodontic treatment for posterior crossbites (Review) 31 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Martina 2012 (Continued) Pterygoid expansion

Molar tipping

Notes The power calculation was based upon previous estimates of rapid maxillary expansion transverse skeletal effects. This indicated that 12 children were needed for each treatment group (to detect 2.5 mm difference, SD = 2.0 mm, significance level = 0.05, power 80%)

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "Balanced block randomisation using gender as a stratifying factor" tion (selection bias)

Allocation concealment Low risk Quote: "A single operator allocated the patients by means of a custom-made (selection bias) Java script and was responsible for the allocation concealment, that is, the allocation was disclosed only when a new patient was enrolled in the trial"

Blinding of outcome as- Low risk Measurements were made by a single operator blinded to participant alloca- sessment (detection bias) tion All outcomes

Incomplete outcome data High risk Numbers of drop-outs and reasons were clearly described in a study workflow (attrition bias) (Figure 4), and were similar. However, dropout rate was very high (Gp A: 48%; All outcomes Gp B: 48%). If the missing participants had higher mean scores in 1 group than the other, as the attrition rate increased, so would over/understatement of the mean difference

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

McNally 2005 Methods Study design: RCT (2 arms)

Location: Queen's Hospital, Burton on Trent and The University of Birmingham, School of Dentistry, Birmingham

Number of centres: 2

Recruitment period: Not stated

Funding source: 3M Unitek supplied the quad-helix arches used in this study

Clinician experience: The authors had used expansion arches of the type tested for a number of years

Participants Inclusion criteria: Either a unilateral or bilateral crossbite that required correction according to the consultant orthodontist

Exclusion criteria: None stated

Age: 11-16 years (not reported by group)

Gender: M/F 30/30 (not reported by group)

Number randomised: 60 (Gp A: 30; Gp B: 30)

Orthodontic treatment for posterior crossbites (Review) 32 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

McNally 2005 (Continued) Number evaluated: 55 (Gp A: 28; Gp B: 27) for molar expansion; 52 (Gp A: 26; Gp B: 26) for canine expansion (the lower numbers were due to unerupted canines)

Interventions Comparison: (Slow expansion) quad-helix + multi-bracket versus expansion arch + multi-bracket

Gp A (n = 30): Quad-helix plus multi-bracket

Gp B (n = 30): Expansion arch plus multi-bracket

In both groups the appliance was activated in order to deliver 1.8-N expansion force

Outcomes Molar and canine expansion

Comfort

Outcomes were measured 4, 8 and 12 weeks after the start of treatment

Notes Altman nomogram for an SD of 1.5 mm at 80% power and 1% significance level suggests a total sample size of 46 children, with 23 in each group

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- High risk Quote: "Using random number tables the first 30 participants were allocated tion (selection bias) for treatment with either appliance according to an odd or even number. The next 30 were then allocated in order to receive the alternative treatment to those in the initial allocation"

Comment: This does not represent a truly random sequence generation

Allocation concealment High risk Quote: "Using random number tables the first 30 participants were allocated (selection bias) for treatment with either appliance according to an odd or even number. The next 30 were then allocated in order to receive the alternative treatment to those in the initial allocation"

Comment: Potential to foresee group allocation

Blinding of outcome as- Unclear risk Quote: "The group of the participant was obvious from the model since the sessment (detection bias) imprint of each type of appliance could be seen. However, since all measure- All outcomes ments were made without reference to previous values, there could be no bias"

Comment: We cannot completely rule out the possibility of bias in this situation

Incomplete outcome data Low risk Numbers of drop-outs and reasons are clearly described in a study workflow (attrition bias) (Figure 4), and are sufficiently similar in each group All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Mossaz-Joelson 1989 Methods Study design: Reclassified as RCT following correspondence (2 arms)

Orthodontic treatment for posterior crossbites (Review) 33 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Mossaz-Joelson 1989 (Continued) Location: Department of Orthodontics, Dental School, University of Geneva, Switzerland

Number of centres: 1

Recruitment period: Not stated

Funding source: Not stated

Clinician experience: Not stated

Participants Inclusion criteria: Children with bilateral or functional unilateral crossbite. No further definition provided

Exclusion criteria: None stated

Age: Gp A: 8.6-10.8 years; Gp B: 8.7-12 years

Gender: M/F 6/4 (not reported by group)

Number randomised: 10 (Gp A: 5; Gp B: 5)

Number evaluated: Not stated

Interventions Comparison: (Fixed appliances) (slow expansion) bonded Minne versus banded Minne appliances

Gp A (n = 5): Conventional Minne expander embedded in acrylic and bonded to upper deciduous first and second molars (or first and second premolars)

Gp B (n = 5): Conventional Minne expander soldered to bands to the upper first primary molars (or first permanent premolars) and upper first molars

A continuous 2-pound (0.9-kg) force coil spring was used to obtain expansion. The spring was re-activated every other week. The slow expansion period lasted 7-15 weeks. After expansion was complete, the fixed appliances were removed, apart from the bonded vertical tubes in Gp A, and the maxillary first molar bands in Gp B. Conventional maxillary retainer worn full time for 12 weeks (retention period). There was then 12 more weeks of observation without the retainers to evaluate relapse

Outcomes Molar and canine expansion

Angular changes

Cephalometric variables

Stability (relapse of molar and canine expansion)

Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk From correspondence with study authors: "...randomly divided into two tion (selection bias) groups..."

Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk From correspondence with study authors: "...randomly divided into two (selection bias) groups..."

Comment: Not mentioned

Orthodontic treatment for posterior crossbites (Review) 34 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Mossaz-Joelson 1989 (Continued) Blinding of outcome as- Unclear risk It appears that it would have been possible to blind outcome assessors as the sessment (detection bias) appliances were removed before final measurements were made. However, it All outcomes was not mentioned

Incomplete outcome data Unclear risk No indication of whether or not there were any drop-outs. Unclear how many (attrition bias) children were included in the outcome assessment All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Oliveira 2004 Methods Study design: RCT (2 arms)

Location: Department of Orthodontics and the Craniofacial Center, University of Illinois at Chicago, USA

Number of centres: 3 university orthodontic clinics and 1 private practice

Recruitment period: Not stated

Funding source: Partially funded by a grant from the American Association of Orthodontists Foundation

Clinician experience: Not stated

Participants Inclusion criteria: Growing children who had maxillary permanent first premolars or non-mobile maxillary deciduous first molar and unilateral or bilateral crossbite

Exclusion criteria: Any craniofacial anomaly

Gp A: mean age 11.9 years (range 10.7-13.4); M/F 5/4

Gp B: mean age 11.1 years (range 7.3-14.6); M/F 1/9

Number randomised: 19 (Gp A: 9; Gp B: 10)

Number evaluated: 19 (Gp A: 9; Gp B: 10)

Interventions Comparison: (Fixed appliances) (rapid expansion) tooth-tissue-borne Haas versus tooth-borne Hyrax

Gp A (n = 9): Tooth-tissue-borne palatal acrylic Haas type expander

Gp B (n = 10): Tooth-borne Hyrax expander (no palatal acrylic)

Appliances were activated twice a day, one-quarter turn each time (0.5 mm/day) until overcorrection was obtained. Appliance was then kept as a retainer for a further 3 months and then removed, at which point the outcomes were measured

Outcomes Molar expansion

Anteroposterior cephalometry

Notes "...projected sample size of 50 subjects" - sample size not met

Risk of bias

Orthodontic treatment for posterior crossbites (Review) 35 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Oliveira 2004 (Continued) Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "Randomization was carried out by using a table of random numbers" tion (selection bias)

Allocation concealment Low risk Quote: "A staJ member in the clinic was informed about every new patient (selection bias) suitable for the study and assigned the type of expander following the list order"

Comment: It appears that allocation was done by someone not involved in the study. Probably done

Incomplete outcome data Low risk No drop-outs reported. Numbers of participants per group reported in the re- (attrition bias) sults tables matched the numbers that were randomised All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Oshagh 2012 Methods Study design: RCT (2 arms)

Location: Orthodontic Department, School of Dentistry, Shiraz University of Medical Sciences, Iran

Number of centres: 1

Recruitment period: Not stated

Funding source: Not stated

Clinician experience: Not stated

Participants Inclusion criteria: Healthy children with posterior bilateral crossbites and with growth potential

Exclusion criteria: Systemic diseases, previous orthodontic treatment, requiring headgear or an auxil- iary component, cleD palate, anterior crossbite, children with extractions

Gp A: mean age 9.85 years (SD 1.87); M/F 6/19

Gp B: mean age 11.2 years (SD 2.46); M/F 5/5

Number randomised: 35 (Gp A: 25; Gp B: 10)

Number evaluated: Not stated

Interventions Comparison: (Removable split acrylic plates) (slow expansion) conventional mid-line expansion screw versus spring-loaded expansion screw

Gp A (n = 25): Conventional screw activated by parent with a one-quarter turn twice per week (total 0.5 mm)

Gp B (n = 10): Spring-loaded screw activated by the orthodontist each month

Orthodontic treatment for posterior crossbites (Review) 36 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Oshagh 2012 (Continued) Both groups were treated by the same orthodontist following the same protocol. Active expansion continued until overcorrection (mean duration of treatment 5.3 months)

Outcomes Molar and canine expansion

Arch size changes

Participant discomfort

Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "Randomization was accomplished by a randomization table" tion (selection bias)

Allocation concealment Unclear risk Quote: "Randomization was accomplished by a randomization table" (selection bias) Comment: Not mentioned

Blinding of outcome as- Unclear risk It appears that it would have been possible to blind outcome assessors as the sessment (detection bias) appliances were removed before casts were made. However, it was not men- All outcomes tioned

Incomplete outcome data Unclear risk No indication of whether or not there were any drop-outs. Unclear how many (attrition bias) children were included in the outcome assessment All outcomes

Selective reporting (re- High risk Poor reporting of results. Only the overall mean monthly changes were report- porting bias) ed. The authors did not report the mean and SD for changes between the baseline and final measurement

Other bias High risk Imbalance in the numbers per group (Gp A: 25; Gp B: 10) and gender (Gp A: M/F 6/19; Gp B: M/F 5/5) suggests a problem with the randomisation

Petrén 2008 Methods Study design: RCT (4 arms)

Location: Public Dental Health Service, Skane County Council, Sweden, and the Department of Ortho- dontics, Faculty of Odontology, Malmö University, Malmö, Sweden

Number of centres: 3

Recruitment period: 2001-2005

Funding source: Supported by the Swedish Dental Society, Skane County Council, and the Faculty of Odontology, Malmö University, Sweden

Clinician experience: 5 experienced general practitioners under the supervision of specialist orthodontists

Participants Inclusion criteria: Mixed dentition (all incisors and first molars erupted); unilateral posterior crossbite

Exclusion criteria: Sucking habits or sucking habit discontinued at less than 1 year before the trial; previous orthodontic treatment

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Petrén 2008 (Continued) Gp A: mean age 9.1 years (SD 1.03); M/F 6/9

Gp B: mean age 8.7 years (SD 0.82); M/F 6/9

Gp C: mean age 8.3 years (SD 0.7); M/F 7/8

Gp D: mean age 8.8 years (SD 0.7); M/F 7/8

Number randomised: 60 (15 per group)

Number evaluated: 60 (15 per group)

Interventions Comparison: (Fixed versus removable appliances) (slow expansion) quad-helix versus expansion plate versus composite onlays versus untreated control group

Gp A (n = 15): The quad-helix consisted of a standard stainless steel arch with stainless steel bands attached with glass ionomer cement on the maxillary first molars. The quad-helix was activated 10 mm before placement and then re-activated every 6 weeks until a crossbite correction. The treatment result was retained for 6 months

Gp B (n = 15): The expansion plate consisted of acrylic with an expansion screw and stainless steel clasps on the deciduous and permanent first molars. The plate was activated 0.2 mm once a week by the child until a normal transverse relationship was achieved. The treatment result was retained for 6 months

Gp C (n = 15): The composite onlay technique was based on the theory that bite raising will inhibit the forced lateral movement and consequently allow the maxilla to grow and develop in the transverse di- mension without locking the mandible in occlusion. The bite raising was achieved by bonding composite on the occlusal surfaces on both mandibular first molars. The composite onlay was checked every 6 weeks and removed after 1 year

Gp D (n = 15): No treatment

Outcomes Crossbite correction

Molar and canine expansion

Time to correction

Notes The sample size for each group had previously been calculated and was based on a significance level 5% and a power of 90%, to detect a mean inter-group difference in expansion of 2 mm (SD 1.5 mm). The sample size calculation showed that each group needed a minimum of 12 children. The sample size tar- get was met

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Low risk Quote: "The subjects were randomized as follows: 4 opaque envelopes were tion (selection bias) prepared with 20 sealed notes in each (5 notes for each group). Thus, for every new patient in the study, a note was extracted from the first envelope. When the envelope was empty, the second envelope was opened, and the 20 new notes were extracted as patients were recruited to the study. This procedure was then repeated 2 more times"

Allocation concealment Low risk Quote: "The envelope was in the care of 1 investigator...who was contacted (selection bias) and randomly extracted a note and informed the dentist which treatment strategy to use"

Blinding of outcome as- Low risk Quote: "Measurements were blinded; the examiner was unaware of which sessment (detection bias) treatment the patients had received or which models were taken at T0 and T1"

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Petrén 2008 (Continued) All outcomes

Incomplete outcome data Low risk Quote: "Data on all patients were analyzed on an intention-to-treat (ITT) ba- (attrition bias) sis... all patients, successful or not, were included in the final analysis" and "all All outcomes patients finished the trial (Fig 5)"

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Ramoglu 2010 Methods Study design: RCT

Location: Department of Orthodontics of Selçuk University, Turkey

Number of centres: 1

Recruitment period: Not stated

Funding source: Selçuk University Research Projects (2003-2004)

Clinician experience: Not stated

Participants Inclusion criteria: Functional unilateral or bilateral posterior crossbite with transverse deficiency; erup- tion of the first permanent molars

Exclusion criteria: Sagittal skeletal problem; more than 1 missing maxillary tooth in the right and leD sides of the dentition

Gp A: mean age 8.63 years (SD 1.09); M/F 7/11

Gp B: mean age 8.78 years (SD 1.21); M/F 6/11

Number randomised: 35 (Gp A: 18; Gp B: 17)

Number evaluated: 35 (Gp A: 18; Gp B: 17)

Interventions Comparison: (Fixed appliances) semi-rapid versus rapid expansion

A splint type tooth- and tissue-borne modified bonded appliance was used for both groups

Gp A (n = 18): Semi-rapid maxillary expansion activation was two-quarter turns per day for the first week followed by one-quarter turn per day every other day. The mean treatment time was 57.16 days (SD 21.52)

Gp B (n = 17): Rapid maxillary expansion activation was two-quarter turns per day throughout treatment, and the mean treatment time was 21.23 days (SD 8.36)

Screw activation was ended when approximately 2 mm of overcorrection was achieved, and the screw was fixed by a ligature wire

Outcomes Molar and canine expansion

Cephalometric treatment effects

Notes No sample size calculation reported

Risk of bias

Orthodontic treatment for posterior crossbites (Review) 39 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Ramoglu 2010 (Continued) Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk Quote: "The subjects were randomly divided into two groups" tion (selection bias) Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk Quote: "The subjects were randomly divided into two groups" (selection bias) Comment: Not mentioned

Incomplete outcome data Low risk No drop-outs reported. Numbers of participants per group reported in the re- (attrition bias) sults tables matches the numbers that were randomised All outcomes

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

Thilander 1984 Methods Study design: RCT

Location: Public Dental Health Service, Enköping, Sweden

Number of centres: 1

Recruitment period: 1965-1967

Funding source: Grant of Swedish Medical Research Council

Clinician experience: Not stated

Participants Inclusion criteria: Children with posterior crossbites. No further definition provided

Exclusion criteria: None stated

Gp A: All children 5 years of age, M/F 13/20

Gp B: All children 5 years of age, M/F 11/17

Number randomised: 68 (Gp A: 34; Gp B: 34)

Number evaluated: 61 (Gp A: 33; Gp B: 28)

Interventions Comparison: Grinding or grinding + expansion plate versus no intervention

Gp A (n = 34): Treatment procedure comprised interceptive measures in 2 steps: grinding and, in the event of unsatisfactory results, expansion plates

Gp B (n = 34): No treatment Gp A were treated with grinding at age 5 years. Gp B remained untreated until the study finished 8 years later at age 13 years. Follow-up measurements to assess crossbite correction were made at age 6, 7, 10 and 13 years

Orthodontic treatment for posterior crossbites (Review) 40 Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Cochrane Trusted evidence. Informed decisions. Library Better health. Cochrane Database of Systematic Reviews

Thilander 1984 (Continued) Outcomes Correction of crossbite

Notes No sample size calculation reported

Risk of bias

Bias Authors' judgement Support for judgement

Random sequence genera- Unclear risk Quote: "68 children...were randomly divided into two groups" tion (selection bias) Comment: Insufficient information on the method of sequence generation

Allocation concealment Unclear risk Quote: "68 children...were randomly divided into two groups" (selection bias) Comment: Not mentioned

Blinding of outcome as- Unclear risk Not mentioned sessment (detection bias) All outcomes

Incomplete outcome data High risk The dropout rate was very different between the treated group (3%) and the (attrition bias) untreated group (18%). Reasons reported were lack of interest in the untreat- All outcomes ed group and relocation from the town

Selective reporting (re- Low risk Outcome measures described in the methods section were reported in full porting bias)

Other bias Low risk No other sources of bias identified

F: female; Gp: group; M: male; N: number; RCT: randomised controlled trial; SD: standard deviation.

Characteristics of excluded studies [ordered by study ID]

Study Reason for exclusion

Petrén 2011 Study including some of the participants from Petrén 2008 plus other participants and matched controls

Weissheimer 2011 Participants with maxillary deficiency, not crossbite

D A T A A N D A N A L Y S E S

Comparison 1. Fixed rapid (Haas) versus fixed rapid (Hyrax)

Outcome or subgroup title No. of No. of Statistical method Effect size studies participants

1 Molar expansion (3 months after completion of ex- 2 27 Mean Difference (IV, Fixed, 95% 0.70 [-0.25, pansion phase) CI) 1.66]

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Analysis 1.1. Comparison 1 Fixed rapid (Haas) versus fixed rapid (Hyrax), Outcome 1 Molar expansion (3 months aOer completion of expansion phase).

Study or subgroup Haas Hyrax Mean Difference Weight Mean Difference N Mean(SD) N Mean(SD) Fixed, 95% CI Fixed, 95% CI Garib 2005 4 6.5 (1) 4 6.7 (0.4) 81.76% -0.2[-1.26,0.86] Oliveira 2004 9 8.5 (2.3) 10 3.7 (2.6) 18.24% 4.76[2.53,6.99]

Total *** 13 14 100% 0.7[-0.25,1.66] Heterogeneity: Tau]=0; Chi]=15.47, df=1(P<0.0001); I]=93.54% Test for overall effect: Z=1.45(P=0.15)

Favours Hyrax -20 -10 0 10 20 Favours Haas

Comparison 2. Fixed slow (quad-helix) versus removable slow (expansion plate)

Outcome or subgroup title No. of No. of Statistical method Effect size studies participants

1 Crossbite correction 2 96 Risk Ratio (M-H, Fixed, 95% CI) 1.20 [1.04, 1.37]

2 Molar expansion 2 96 Mean Difference (IV, Fixed, 95% CI) 1.15 [0.40, 1.90]

3 Canine expansion 2 96 Mean Difference (IV, Fixed, 95% CI) 0.19 [-0.47, 0.85]

Analysis 2.1. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 1 Crossbite correction.

Study or subgroup Quad-helix Expan- Risk Ratio Weight Risk Ratio sion plate n/N n/N M-H, Fixed, 95% CI M-H, Fixed, 95% CI Godoy 2011 33/33 30/33 74.39% 1.1[0.97,1.24] Petrén 2008 15/15 10/15 25.61% 1.48[1.02,2.13]

Total (95% CI) 48 48 100% 1.2[1.04,1.37] Total events: 48 (Quad-helix), 40 (Expansion plate) Heterogeneity: Tau]=0; Chi]=3.15, df=1(P=0.08); I]=68.28% Test for overall effect: Z=2.58(P=0.01)

Favours expansion plate 0.1 0.2 0.5 1 2 5 10 Favours quad-helix

Analysis 2.2. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 2 Molar expansion.

Study or subgroup Quad-helix Expansion plate Mean Difference Weight Mean Difference N Mean(SD) N Mean(SD) Fixed, 95% CI Fixed, 95% CI Godoy 2011 33 4.3 (2.4) 33 3.1 (2.4) 41.97% 1.22[0.06,2.38]

Favours expansion plate -2 -1 0 1 2 Favours quad-helix

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Study or subgroup Quad-helix Expansion plate Mean Difference Weight Mean Difference N Mean(SD) N Mean(SD) Fixed, 95% CI Fixed, 95% CI Petrén 2008 15 4.6 (1.2) 15 3.5 (1.5) 58.03% 1.1[0.12,2.08]

Total *** 48 48 100% 1.15[0.4,1.9] Heterogeneity: Tau]=0; Chi]=0.02, df=1(P=0.88); I]=0% Test for overall effect: Z=3.01(P=0)

Favours expansion plate -2 -1 0 1 2 Favours quad-helix

Analysis 2.3. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 3 Canine expansion.

Study or subgroup Quad-helix Expansion plate Mean Difference Weight Mean Difference N Mean(SD) N Mean(SD) Fixed, 95% CI Fixed, 95% CI Godoy 2011 33 3 (2.5) 33 1.4 (1.8) 40.07% 1.53[0.49,2.57] Petrén 2008 15 2 (1.2) 15 2.7 (1.2) 59.93% -0.7[-1.55,0.15]

Total *** 48 48 100% 0.19[-0.47,0.85] Heterogeneity: Tau]=0; Chi]=10.55, df=1(P=0); I]=90.52% Test for overall effect: Z=0.58(P=0.56)

Favours expansion plate -2 -1 0 1 2 Favours quad-helix

A D D I T I O N A L T A B L E S

Table 1. Fixed versus fixed with mid-palatal expansion (single study comparisons) Study Outcome Group A Group B Results

Asanza Molar expansion (3 months af- Hyrax banded: Mean 6 Hyrax bonded: Mean P value = NS (as reported in the 1997 ter completion of expansion mm (min 4.3 mm - max 5.9 mm (min 3.2 mm - study - no SD reported) phase) 7.2 mm) max 7.7 mm)

Kilic 2008 Molar expansion (1 week af- Hyrax banded: Mean Hyrax bonded: Mean MD 0.36 (95% CI -0.72 to 1.44) ter completion of expansion 7.67 mm (SD 1.99) 7.31 mm (SD 1.45) phase) P value = 0.51

Lagravere Molar expansion (6 months af- Hyrax tooth-borne ex- Bone-anchored ex- MD 0.08 (95% CI -1.00 to 1.16) 2010 ter completion of expansion pander: Mean 5.83 mm pander: Mean 5.75 mm phase) (SD 1.54) (SD 1.98) P value = 0.88

Molar expansion (12 months Hyrax tooth-borne ex- Bone-anchored ex- MD 0.21 (95% CI -0.77 to 1.19) after completion of expansion pander: Mean 4.24 mm pander: Mean 4.03 mm phase) (SD 1.69) (SD 1.49) P value = 0.67

Lamparski Molar expansion (3 months af- 4-point expansion ap- 2-point expansion ap- P value = "No significant differ- 2003 ter completion of expansion pliance (Hyrax): Not re- pliance: Not reported ences were found" phase) ported by group by group

Canine expansion (3 months 4-point expansion ap- 2-point expansion ap- P value = 0.331 (as reported in after completion of expansion pliance (Hyrax): Mean pliance: Mean 1.7 mm the study - no SD reported) phase) 3.034 mm

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Table 1. Fixed versus fixed with mid-palatal expansion (single study comparisons) (Continued) Martina Molar expansion (7 months af- Slow maxillary expan- Rapid maxillary ex- MD 0.60 (95% CI -0.85 to 2.05) 2012 ter start of treatment) sion: pansion: P value = 0.42 Mean 6.3 mm (SD 2.1) Mean 5.7 mm (SD 1.6)

Mossaz- Molar expansion (7-15 weeks Bonded Minne: Mean Banded Minne: Mean P value = NS (as reported in the Joelson after start of treatment) 7.9 mm (SD 1.5) 8.3* mm (SD 1.1) study - number of participants 1989 included in analysis not reported)

Canine expansion (7-15 weeks Bonded Minne: Mean Banded Minne: Mean P value = NS (as reported in the after start of treatment) 6.4 mm (SD 1.1) 5.3 mm (SD 1.9) study - number of participants included in analysis not reported)

Stability: relapse of molar ex- Bonded Minne: Mean Banded Minne: Mean P value = NS (as reported in the pansion (24 weeks after com- 2.3 mm (SD 0.8) 2.5 mm (SD 0.6) study - number of participants pletion of expansion phase) included in analysis not reported)

Stability: relapse of canine ex- Bonded Minne: Mean Banded Minne: Mean P value = NS (as reported in the pansion (24 weeks after com- 1.6 mm (SD 0.5) 1.2 mm (SD 0.3) study - number of participants pletion of expansion phase) included in analysis not reported)

Ramoglu Molar expansion Semi-rapid maxillary Rapid maxillary ex- MD 0.60 (95% CI -0.55 to 1.75) 2010 expansion: Mean 5.71 pansion: Mean 5.11 mm (SD 1.66) mm (SD 1.81) P value = 0.31

Canine expansion Semi-rapid maxillary Rapid maxillary ex- MD 0.36 (95% CI -0.64 to 1.36) expansion: Mean 5.13 pansion: Mean 4.77 mm (SD 1.47) mm (SD 1.53) P value = 0.48

CI: confidence interval; MD: mean diJerence; min: minimum; max: maximum; NS: not significant; RR: risk ratio; SD: standard deviation. * There is a discrepancy between the mean reported in Table 1 (5.3) and the text (8.3). The latter must be the actual mean as the text reports that there is no significant diJerence, whereas if the mean were 5.3, the P value is < 0.05 (based on assumption of no drop-outs).

Table 2. Fixed versus removable (single study comparisons) Study Outcome Group A Group B Results

Godoy Stability of cross- Quad-helix: Removable expansion RR 1 (95% CI 0.43 to 2.32) 2011 bite correction (re- plate: lapse 12 months af- 3/33 P value = 1 ter correction) 3/33

Petrén Crossbite correc- Quad-helix: 15/15 Composite onlays: 2/15 RR 6.20 (95% CI 1.98 to 19.43) 2008 tion P value = 0.002

Molar expansion Quad-helix: Mean 4.6 mm Composite onlays: Mean 0.5 MD 4.10 (95% CI 3.45 to 4.75) (SD 1.19) mm (SD 0.46) P value < 0.00001

Canine expansion Quad-helix: Mean 2 mm Composite onlays: Mean MD 1.37 (95% CI 0.68 to 2.06) (SD 1.18) 0.63 mm (SD 0.7) P value = 0.0001

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Table 2. Fixed versus removable (single study comparisons) (Continued) Crossbite correc- Removable expansion Composite onlays: 2/15 RR 5 (95% CI 1.31 to 19.07) tion plate: 10/15 P value = 0.02

Molar expansion Removable expansion Composite onlays: Mean 0.5 MD 3.00 (95% CI 2.19 to 3.81) plate: Mean 3.5 mm (SD mm (SD 0.46) 1.54) P value < 0.00001

Canine expansion Removable expansion Composite onlays: Mean MD 2.07 (95% CI 1.37 to 2.77) plate: Mean 2.7 mm (SD 0.63 mm (SD 0.7) 1.2) P value < 0.00001

CI: confidence interval; MD: mean diJerence; NS: not significant; RR: risk ratio; SD: standard deviation

Table 3. Other single study comparisons Study Outcome Group A Group B Results

Lippold Molar expansion (12 Fixed bonded Hyrax appliance No treatment: Mean P value < 0.001 (as reported 2013 months after start of followed by U-bow activator: 0.8 mm in the study - no SD for mean treatment) Mean 5.1 mm change from baseline reported)

Canine expansion (12 Fixed bonded Hyrax appliance No treatment: Mean P value < 0.001 (as reported months after start of followed by U-bow activator: 1 mm in the study - no SD for mean treatment) Mean 3.6 mm change from baseline reported)

McNally Molar expansion (12 Quad-helix + multi-bracket: Expansion arch MD -0.55 (95% CI -1.34 to 0.24) 2005 weeks after start of treat- Mean 4.54 mm (SD 1.27) + multi-bracket: ment) Mean 5.09 mm (SD P value = 0.17 1.67)

Canine expansion (12 Quad-helix + multi-bracket: Expansion arch MD -0.72 (95% CI -1.52 to 0.08) weeks after start of treat- Mean 1.4 mm (SD 1.75) + multi-bracket: ment) Mean 2.12 mm (SD P value = 0.08 1.11)

Oshagh Molar and canine expan- Removable with conventional Removable with Results inadequately reported 2012 sion screw spring-loaded screw

Thilander Crossbite correction Grinding or grinding + expan- No treatment: RR 3.68 (95% CI 1.77 to 7.64) 1984 sion plate: 6/28 P value = 0.0005 26/33

CI: confidence interval; MD: mean diJerence; NS: not significant; RR: risk ratio; SD: standard deviation.

A P P E N D I C E S

Appendix 1. Description of appliances that can be used to treat posterior crossbite Fixed appliances (with mid-palatal screw) Bonded (acrylic splint) An alternative to the banded design, this fixed expander uses posterior acrylic coverage that is bonded directly to the teeth. The posterior bite blocks free up the occlusion by removing cuspal interferences.

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Bone-anchored expander The bone-anchored expander is composed of 2 custom-milled stainless steel onplants, 2 miniscrews and an expansion screw. The expansion screw placed in palatal mid-line is anchored directly to the palatal surfaces of the maxilla (top jaw) with either bioglass-coated aluminium oxide implants or osteosynthesis plates.

Expansion arch The expansion arch is made from 1.135 mm round stainless steel wire bent into the shape of a dental arch and inserted into the extra- oral traction tubes on the first molar bands.

Haas A fixed maxillary expander that uses acrylic pads and heavy lingual wires to apply pressure to both the teeth and the palatal tissue during expansion. The lingual wires are soldered to bands on the first bicuspids and the first molars and extend into the palate where they are embedded in the acrylic pads.

Hyrax A fixed metal expander soldered to bands on the first molars (2 points) or first molars and first bicuspids (4 points) with an 0.036-mm lingual wire connecting the bands.

Minne expander This is a tooth-borne appliance without any acrylic palatal covering. This design makes use of a spring loaded screw called a Minne expander. The first premolars and molars are banded. Metal flanges are soldered onto the bands on the buccal and lingual sides. The expander consists of a coil spring having a nut that can compress the spring. This coil spring is made to extend between the lingual metal flanges that have been soldered. The expander is activated by closing the nut so that the spring is compressed.

Quad helix This fixed metal expander (also available as a fixed/removable) is capable of applying forces in numerous directions depending upon how it is activated. The 4 helical loops (2 in the first bicuspid region and 2 in the second molar region) can be activated in unison or individually to achieve the desired results. The appliance is soldered to bands on the first molars and lingual arms run from the bands forwards to the cuspids or first bicuspids as desired.

Removable appliances Upper removable appliance The upper removable appliance is an expansion plate made of acrylic, with an expansion screw and steel clasps on the first deciduous and permanent molars.

Appendix 2. MEDLINE via OVID search strategy 1. (cross-bite$ or crossbite$).mp. 2. (posterior adj8 (teeth or tooth or dental)).mp. 3. (anteroposterior adj8 (teeth or tooth or dental)).mp. 4. "dentoalveolar inclin$".mp. 5. ((palat$ or maxilla$) adj3 (expand$ or expansion)).mp. 6. or/1-5 7. exp Orthodontics, corrective/ 8. exp Orthodontics, interceptive/ 9. (expan$ and (appliance$ or device$)).mp. 10. ((transpalatal or trans-palatal) and arch$).mp. 11. ("mandibular arch$" and contract$).mp. 12. (ipomaxilla$ and (correct$ or therap$)).mp. 13. ("criss-cross elastic$" or "criss cross elastic$").mp. 14. (occlusal and grind$).mp. 15. or/7-14 16. 6 and 15

The above subject search was linked to the Cochrane Highly Sensitive Search Strategy (CHSSS) for identifying randomised trials in MEDLINE: sensitivity maximising version (2008 revision) as referenced in Chapter 6.4.11.1 and detailed in box 6.4.c of theCochrane Handbook for Systematic Reviews of Interventions, Version 5.1.0 [updated March 2011] (Higgins 2011).

1. randomized controlled trial.pt. 2. controlled clinical trial.pt. 3. randomized.ab. 4. placebo.ab. 5. drug therapy.fs.

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6. randomly.ab. 7. trial.ab. 8. groups.ab. 9. or/1-8 10. exp animals/ not humans.sh. 11. 9 not 10

Appendix 3. The Cochrane Oral Health Group's Trials Register search strategy 1 ((crossbite* or cross-bite* or "cross bite*"):ti,ab) AND (INREGISTER) 2 (("posterior teeth" or "posterior tooth"):ti,ab) AND (INREGISTER) 3 ((posterior and dental):ti,ab) AND (INREGISTER) 4 ((anteroposterior):ti,ab) AND (INREGISTER) 5 ("dentoalveolar inclin*":ti,ab) AND (INREGISTER) 6 (((palat* or maxilla*) AND (expand* or expansion)):ti,ab) AND (INREGISTER) 7 (#1 or #2 or #3 or #4 or #5 or #6) AND (INREGISTER) 8 ((orthodontic* or interceptive):ti,ab) AND (INREGISTER) 9 ((expan* and (appliance* or device*)):ti,ab) AND (INREGISTER) 10 (((transpalatal or trans-palatal) and arch*):ti,ab) AND (INREGISTER) 11 (("mandibular arch*" and contract*):ti,ab) AND (INREGISTER) 12 ((ipomaxilla* and (correct* or therap*)):ti,ab) AND (INREGISTER) 13 (("criss-cross elastic*" or "criss cross elastic*"):ti,ab) AND (INREGISTER) 14 ((occlusal and grind*):ti,ab) AND (INREGISTER) 15 (#8 or #9 or #10 or #11 or #12 or #13 or #14) AND (INREGISTER) 16 (#7 and #15) AND (INREGISTER)

Appendix 4. The Cochrane Central Register of Controlled Trials (CENTRAL) search strategy #1 (cross-bite* in All Text or crossbite* in All Text or "cross bite*" in All Text) #2 ((posterior in All Text near/6 teeth in All Text) or (posterior in All Text near/6 tooth in All Text) or (posterior in All Text near/6 dental in All Text)) #3 ((anteroposterior in All Text near/6 teeth in All Text) or (anteroposterior in All Text near/6 tooth in All Text) or (anteroposterior in All Text near/6 dental in All Text)) #4 "dentoalveolar inclin*" in All Text #5 ((palat* in All Text or maxilla* in All Text) and (expand* in All Text or expansion in All Text)) #6 (#1 or #2 or #3 or #4 or #5) #7 MeSH descriptor Orthodontics, corrective explode all trees #8 (orthodontic* in All Text or interceptive in All Text) #9 (expan* in All Text and (appliance* in All Text or device* in All Text)) #10 ((transpalatal in All Text or trans-palatal in All Text) and arch* in All Text) #11 ("mandibular arch*" in All Text and contract* in All Text) #12 (ipomaxilla* in All Text and (correct* in All Text or therap* in All Text)) #13 ("criss-cross elastic*" in All Text or "criss cross elastic*" in All Text) #14 (occlusal in All Text and grind* in All Text) #15 (#7 or #8 or #9 or #10 or #11 or #12 or #13 or #14) #16 (#6 and #15)

Appendix 5. EMBASE via OVID search strategy 1. (cross-bite$ or crossbite$).mp. 2. (posterior adj8 (teeth or tooth or dental)).mp. 3. (anteroposterior adj8 (teeth or tooth or dental)).mp. 4. "dentoalveolar inclin$".mp. 5. ((palat$ or maxilla$) adj3 (expand$ or expansion)).mp. 6. or/1-5 7. (expan$ and (appliance$ or device$)).mp. 8. ((transpalatal or trans-palatal) and arch$).mp. 9. ("mandibular arch$" and contract$).mp. 10. (ipomaxilla$ and (correct$ or therap$)).mp. 11. ("criss-cross elastic$" or "criss cross elastic$").mp. 12. (occlusal and grind$).mp. 13. Orthodontics/ 14. or/7-13

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15. 6 and 14

The above subject search was linked to the Cochrane Oral Health Group filter for identifying randomised controlled trials in EMBASE via OVID:

1. random$.ti,ab. 2. factorial$.ti,ab. 3. (crossover$ or cross over$ or cross-over$).ti,ab. 4. placebo$.ti,ab. 5. (doubl$ adj blind$).ti,ab. 6. (singl$ adj blind$).ti,ab. 7. assign$.ti,ab. 8. allocat$.ti,ab. 9. volunteer$.ti,ab. 10. CROSSOVER PROCEDURE.sh. 11. DOUBLE-BLIND PROCEDURE.sh. 12. RANDOMIZED CONTROLLED TRIAL.sh. 13. SINGLE BLIND PROCEDURE.sh. 14. or/1-13 15. (exp animal/ or animal.hw. or nonhuman/) not (exp human/ or human cell/ or (human or humans).ti.) 16. 14 NOT 15

Appendix 6. US National Institutes of Health Trials Register and the World Health Organization (WHO) International Clinical Trials Registry Platform search strategy orthodontic AND posterior AND crossbite

W H A T ' S N E W

Date Event Description

4 April 2014 New search has been performed Searches updated to 21 January 2014.

4 April 2014 New citation required and conclusions Inclusion criteria changed to only include randomised controlled have changed trials (RCTs). Therefore we have discarded six of the controlled clinical trials included in the previous version. To the remaining three RCTs we have added 12 new included RCTs in this update.

All sections updated to reflect up-to-date Cochrane review methodology and methodological expectations of Cochrane intervention reviews (MECIR). Risk of bias assessment of included studies carried out and summary of findings tables added.

H I S T O R Y

Protocol first published: Issue 1, 1998 Review first published: Issue 4, 1998

Date Event Description

23 June 2008 Amended Converted to new review format.

16 November 2000 New citation required but conclusions Substantive amendment. A further CCT has been found on two- have not changed point versus four-point expansion (Schneiderman 1990) and follow-up data on the treatment group from Lindner 1989 (Tsarap- atsani 1999). Conclusions remain largely unchanged.

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C O N T R I B U T I O N S O F A U T H O R S

Jayne Harrison (JH) and Deborah Ashby wrote the protocol and previous versions of the review.

For the update:

• screening the search results and retrieving the papers: Paola Agostino (PA), Alessandro Ugolini (AU), Armando Silvestrini-Biavati (ASB); • data extraction and risk of bias assessment: PA, AU, ASB, Alessio Signori (AS), Philip Riley (PR); • analysing the data and interpreting the results: PA, AU, PR, AS, Jayne Harrison (JH); • creating the 'Summary of findings' (GRADE) tables: PR; • writing the results, discussion and conclusions: PA, AU, PR, JH.

D E C L A R A T I O N S O F I N T E R E S T

Paola Agostino, Alessio Signori, Armando Silvestrini-Biavati, Alessandro Ugolini, Jayne E Harrison, Philip Riley: no interests to declare.

S O U R C E S O F S U P P O R T

Internal sources • Department of Surgical and Diagnostic Sciences, University of Genoa, Italy.

Provision of IT support and open access to the university library. • Royal Liverpool and Broadgreen University Hospitals Trust (RLBUHT)/NHS, UK. • School of Dentistry, The University of Manchester, UK. • MAHSC, UK.

The Cochrane Oral Health Group is supported by the Manchester Academic Health Sciences Centre (MAHSC) and the NIHR Manchester Biomedical Research Centre.

External sources • National Health Service (NHS), UK.

Jayne Harrison received research and development grant funding support for previous versions of this review. • Cochrane Oral Health Group Global Alliance, UK.

All reviews in the Cochrane Oral Health Group are supported by Global Alliance member organisations (British Association of Oral Surgeons, UK; British Orthodontic Society, UK; British Society of Paediatric Dentistry, UK; British Society of Periodontology, UK; Canadian Dental Hygienists Association, Canada; Mayo Clinic, USA; National Center for Dental Hygiene Research & Practice, USA; New York University College of Dentistry, USA; and Royal College of Surgeons of Edinburgh, UK) providing funding for the editorial process (http://ohg.cochrane.org/). • National Institute for Health Research (NIHR), UK.

CRG funding acknowledgement: The NIHR is the largest single funder of the Cochrane Oral Health Group.

Disclaimer: The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the NIHR, NHS or the Department of Health.

D I F F E R E N C E S B E T W E E N P R O T O C O L A N D R E V I E W

• The original protocol and previous versions of this review included controlled clinical trials (CCTs) and quasi-RCTs. In order to attempt to limit bias, we only included RCTs in this update. • We clarified that 'correction of crossbite' is the primary outcome of this review by listing is as such in the 'Methods' section.

I N D E X T E R M S

Medical Subject Headings (MeSH) Orthodontic Appliances; Orthodontic Retainers; Orthodontics, Corrective [*methods]; Overbite [*therapy]; Palatal Expansion Technique; Randomized Controlled Trials as Topic; Temporomandibular Joint Dysfunction Syndrome [therapy]

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MeSH check words Adolescent; Child; Child, Preschool; Humans