Download Research paper: Orthodontic treatment for posterior crossbites

Orthodontic treatment for posterior crossbites (Review)
Agostino P, Ugolini A, Signori A, Silvestrini-Biavati A, Harrison JE, Riley P
This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library
2014, Issue 8
http://www.thecochranelibrary.com
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
TABLE OF CONTENTS
HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLAIN LANGUAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SUMMARY OF FINDINGS FOR THE MAIN COMPARISON . . . . . . . . . . . . . . . . . . .
BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADDITIONAL SUMMARY OF FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . .
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AUTHORS’ CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACKNOWLEDGEMENTS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHARACTERISTICS OF STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DATA AND ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 1.1. Comparison 1 Fixed rapid (Haas) versus fixed rapid (Hyrax), Outcome 1 Molar expansion (3 months after
completion of expansion phase). . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 2.1. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 1 Crossbite
correction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 2.2. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 2 Molar
expansion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analysis 2.3. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 3 Canine
expansion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADDITIONAL TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WHAT’S NEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CONTRIBUTIONS OF AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DECLARATIONS OF INTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SOURCES OF SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIFFERENCES BETWEEN PROTOCOL AND REVIEW . . . . . . . . . . . . . . . . . . . . .
INDEX TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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[Intervention Review]
Orthodontic treatment for posterior crossbites
Paola Agostino1 , Alessandro Ugolini2 , Alessio Signori3 , Armando Silvestrini-Biavati2 , Jayne E Harrison4 , Philip Riley5
1 Private practice, Chiavari, Italy. 2 Orthodontics Department, University of Genoa, Genoa, Italy. 3 Unit of Biostatistics, Health Sciences
Department, University of Genoa, Genoa, Italy. 4 Orthodontic Department, Liverpool University Dental Hospital, Liverpool, UK.
5 Cochrane 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.
Review content assessed as up-to-date: 21 January 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.
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
ABSTRACT
Background
A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. When it affects 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 effects 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
differences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-effect models (we would
have used random-effects models if we had included four or more studies in a meta-analysis) when comparisons and outcomes were
sufficiently similar.
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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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
Nine studies tested fixed appliances with mid-palatal expansion against each other. No study reported a difference 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 insufficient evidence of a difference 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 insufficient evidence of a difference 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 insufficient to allow the conclusion
that any one intervention is better than another for any of the outcomes in this review.
PLAIN LANGUAGE SUMMARY
Orthodontic treatment for posterior crossbites
Review question
We conducted this review to assess the effects of different 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 affects 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 shifts to one side into a position that allows more teeth to come into contact.
However, this shifting 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 effective 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 effective 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)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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appliances either against different fixed appliances, or against the same fixed appliance but comparing different rates of expansion. Two
studies compared a fixed appliance with a removable appliance. The remaining four studies evaluated other comparisons that were
more difficult 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
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)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
S U M M A R Y O F F I N D I N G S F O R T H E M A I N C O M P A R I S O N [Explanation]
Fixed appliances compared with other fixed appliances for treating posterior crossbites
Patient or population: Children with posterior crossbites (adults would be included in the review but no studies with adults were found)
Settings: Typically university orthodontic/dental clinics
Intervention: Fixed appliance
Comparison: The same fixed appliance attached differently or expanded at different speeds or a different fixed appliance
Outcomes
Illustrative comparative risks (95% CI)
Assumed risk
Corresponding risk
Group A
Group B
Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Molar expansion
N/A
(mm)
(rapid
expansion) banded Hyrax
(tooth borne) versus
bonded Hyrax (tooth/tissue borne)
N/A
N/A
53
(2)
⊕
very low
2 studies (1 high risk of
bias; 1 unclear), which
were not possible to pool
in a meta-analysis due to
no reporting of variance in
1 study. Imprecision due
to low sample sizes. Different timings of followup after completion of expansion. Both studies reported no difference in
molar expansion
Molar expansion
(mm)
(3 months after completion of expansion phase)
(rapid expansion) toothtissue borne (Haas) versus tooth borne (Hyrax)
The mean expansion in N/A
the Hyrax groups was
0.7 mm lower
(1.66 lower to 0.25
higher)
27
(2)
⊕
very low
2 studies at unclear risk
of bias with serious inconsistency (I2 = 94%)
and imprecision due to
low sample size
The mean expansion
ranged across the Haas
groups from
6.5 to 8.49 mm
4
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Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
N/A
N/A
N/A
N/A
N/A
N/A
CI: confidence interval; N/A: not applicable.
GRADE Working Group grades of evidence
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.
The remaining comparisons were all single studies (Additional Table 1)
. The quality of the evidence (GRADE) for all
comparisons and outcomes in Additional Table
1 is ⊕ very low
(all at unclear or high risk
of bias with imprecision
due to low sample sizes)
. None of these studies
showed a statistically significant difference for any
outcome
5
BACKGROUND
habit (e.g. thumb sucking) or some pathology (Bresolin 1983;
Cheng 1988; Modeer 1982; Ogaard 1994; Subtelny 1980).
Description of the condition
Description of the intervention
Posterior crossbite is the term used to describe the situation when
the top back teeth bite inside the bottom back teeth. A posterior
crossbite occurs when the top teeth or jaw are narrower than the
bottom teeth and can happen on one (unilateral) or both (bilateral) sides of the mouth. The prevalence of posterior crossbites is
between 1% and 16% of children who only have their baby teeth,
and is likely to be higher in white populations compared with children of African or Asian ethnicity (Malandris 2004). Most posterior crossbites (50% to 90%) persist when the permanent teeth
erupt, though, in a minority of children, the malocclusion self
corrects.
A functional posterior crossbite occurs when there is an interference between two or more teeth when an individual closes their
jaws together. In order to obtain a more comfortable bite, the
mandible (lower jaw) shifts to one side into a position that allows more teeth to come into contact. However, this displacement
may increase the likelihood of the individual developing bruxism
(tooth grinding), which may lead to other dental problems including the tooth surface being worn away (Malandris 2004), abnormal growth and development of the teeth and jaws, and jaw joint
problems.
While it is unlikely that young children with a posterior crossbite
will experience any pain or have problems with chewing, there
has been concern that the abnormal movement of the lower jaw
associated with a crossbite could potentially have long-term effects
on the growth and development of the teeth and jaws. The strain
on the jaw muscles and joints due to the abnormal movement and
position of the lower jaw may lead to skeletal facial asymmetries
that can be corrected during adulthood only by means of a combination of orthodontics and maxillofacial surgery.
Some studies have reported a correlation between posterior crossbite with a shift on closure and temporomandibular joint problems in later life, for example pain, clicking or locking of the jaw
joints. Such problems have many causes but studies of teenagers
and adults have shown that some people with a crossbite may
have an increased risk of developing jaw joint problems and show
more signs and symptoms of these problems (Egermark 1990;
McNamara 1997; Ninou 1994; O’Bryn 1995; Pullinger 1993).
However, some more recent studies have been less conclusive regarding an association between posterior crossbites and jaw problems (Gesch 2004; Iodice 2013; Thilander 2002; Thilander 2012).
A posterior crossbite may develop or improve at any time from
when the deciduous (baby) teeth come into the mouth to when
the permanent (adult) teeth come through (Heikinheimo 1987;
Kurol 1992; Leighton 1966; Thilander 1984). It is unclear what
causes posterior crossbites but they may be due to skeletal, soft
tissue, dental or respiratory factors, or develop as the result of a
As described above, a posterior crossbite may self correct but, as self
correction occurs in only a very small minority of cases, treatment
of this malocclusion can be recommended. Treatment of a posterior crossbite usually involves expansion of the maxillary (upper
jaw) arch, removal of any occlusal interferences and elimination
of the functional displacement of the mandible.
Maxillary expansion treatment initiated during the early mixed
dentition stage (children younger than eight years of age) may require the use of lower forces to achieve expansion of the upper
arch because the mid-line bony suture has not yet fused. However,
obtaining co-operation with treatment may be more difficult in
younger children and treatment may be complicated by the loss
of deciduous teeth. In older children (aged 12 years and above)
who are in the early permanent dentition, greater forces may be
required to achieve maxillary expansion. Maxillary expansion can
be achieved using either fixed or removable appliances and expansion can be either rapid or slow. Expansion of the top jaw 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
per week. Braces that can bring about this expansion are fixed to
the back teeth by either metal bands around the individual teeth
(banded rapid/slow maxillary expansion) or acrylic splints over
several teeth (bonded rapid/slow maxillary expansion) joined by
a wire framework attached to a screw in the mid-line that can be
opened to expand the top jaw.
Removal of occlusal interferences involves grinding of teeth (usually deciduous teeth) to enable the jaws to bite together in a more
normal position. The reported success rate of this approach varied
widely between 27% and 64% (Kennedy 2005; Lindner 1989).
Alternatively, composite onlays can be placed to prevent the jaw
from shifting when interferences exist.
Where functional displacement of the mandible is associated with
reversible causes such as non-nutritive sucking habits (sucking on
a dummy, thumb, finger(s), etc.), eliminating the causal behaviour
is a desirable adjunct to orthodontic treatment.
How the intervention might work
Expansion of the maxillary arch can be achieved through use of
either fixed or removable appliances (see Appendix 1 for a description of appliances). These have expansion screws that are adjusted
during treatment to increase the width of the maxillary arch. Expansion may be either rapid (one-quarter turn of the expansion
screw one or two times per day, giving 0.5 mm expansion per day)
over two to six weeks or slow (one-quarter turn twice per week,
giving 0.5 mm expansion per week) over six to 12 weeks. Over-
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
6
expansion may be appropriate to allow for some relapse after the
appliance is removed. The use of maxillary expansion at the stage
of the early mixed dentition may also have the benefit of reducing
crowding of the permanent dentition.
Orthodontic appliances may also be used to correct the sideways
displacement of the mandible, which may reduce the pressure on
the temporomandibular joint.
Types of interventions
We included studies of any orthodontic or dentofacial orthopaedic
(not surgical) treatment used to correct posterior crossbites or expand the top back teeth, or both, when compared against another
such treatment or no treatment.
Types of outcome measures
Why it is important to do this review
A crossbite is a common transverse feature seen in malocclusions
in the posterior region of the dental arch. There is still debate
about the optimum timing of orthodontic treatment, the use of
either fixed or removable appliances, and the type of appliance
that leads to the best outcomes for the person. This updated systematic review will summarise the evidence available from randomised controlled trials to inform treatment decision making.
The Cochrane Oral Health Group recently carried out a prioritisation exercise for their portfolio of orthodontic reviews, and this
review was ranked in the top 10 most important orthodontic reviews by an international panel of oral health professionals, the
majority of whom were extremely experienced and internationally
renowned orthodontists.
This is an update of a Cochrane review first published in 2001.
Primary
• Correction of the posterior crossbite.
Secondary
• Expansion of the upper jaw/teeth measured as changes in
the width between the molars or canines, or both.
• Stability of crossbite correction.
• Signs and symptoms of temporomandibular joint
dysfunction (e.g. pain, clicking, locking of the jaw joints,
problems eating).
• Signs and symptoms of respiratory disease (e.g. mouth
breathing, nasal airway resistance).
• Quality of life (using any validated measurement tool).
Search methods for identification of studies
OBJECTIVES
To assess the effects of orthodontic treatment for posterior crossbites.
METHODS
Criteria for considering studies for this review
Types of studies
We included randomised controlled trials (RCTs) of parallel design that assessed orthodontic treatments to correct a posterior
crossbite or expand the top back teeth, or both. We included studies irrespective of language or publication status.
Types of participants
We included RCTs of children and adults with a posterior crossbite, without a Class III skeletal relationship, cleft lip or palate (or
both) or other syndrome associated with craniofacial anomalies.
For the identification of studies included or considered for this
review, we developed detailed search strategies for each database
searched. These were based on the search strategy developed for
MEDLINE (OVID) but revised appropriately for each database.
The search strategy used a combination of controlled vocabulary
and free-text terms and was linked with the Cochrane Highly Sensitive Search Strategy (CHSSS) for identifying RCTs in MEDLINE: sensitivity maximising version (2008 revision) as referenced
in Chapter 6.4.11.1 and detailed in box 6.4.c of the Cochrane
Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011) (Higgins 2011). Details of the MEDLINE
search are provided in Appendix 2. The search of EMBASE was
linked to the Cochrane Oral Health Group filter for identifying
RCTs.
Electronic searches
We searched the following electronic databases:
• the Cochrane Oral Health Group’s Trials Register (to 21
January 2014) (Appendix 3);
• the Cochrane Central Register of Controlled Trials
(CENTRAL) (The Cochrane Library, 2014, Issue 1) (Appendix
4);
• MEDLINE via OVID (1946 to 21 January 2014)
(Appendix 2)
Orthodontic treatment for posterior crossbites (Review)
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• EMBASE via OVID (1980 to 21 January 2014) (Appendix
5).
We manually checked all the references lists of the included studies
to identify any additional studies.
We placed no restrictions on the language or date of publication
when searching the electronic databases.
Searching other resources
We searched the following databases for ongoing trials (see
Appendix 6 for the search strategy):
• US National Institutes of Health Trials Register (
clinicaltrials.gov) (to 21 January 2014);
• The WHO Clinical Trials Registry Platform (apps.who.int/
trialsearch/default.aspx) (to 21 January 2014).
We handsearched the following journals from 1970 to 2012:
• European Journal of Orthodontics;
• American Journal of Orthodontics and Dentofacial
Orthopedics;
• Orthodontics and Craniofacial Research;
• The Angle Orthodontist.
In the previous version of this review we also handsearched:
• British Journal of Orthodontics;
• Journal of Orthodontics.
We also searched personal references. We contacted the investigators of the included studies by email to ask for additional details
of their trials and for any information they may have about any
further published and unpublished trials.
Data collection and analysis
Selection of studies
Two review authors screened the titles and abstracts of the results
of the searches, independently and in duplicate. We obtained fulltext copies of all studies that appeared to meet the inclusion criteria, and of all those that were unclear due to insufficient information in the title or abstract, or both. Two review authors assessed the full-text papers independently and in duplicate in order to ensure that they met the inclusion criteria. We contacted
study authors for clarification or missing information where necessary and possible. We resolved any disagreements by discussion.
A member of The Cochrane Collaboration translated any nonEnglish language studies. We recorded any studies that did not
meet the inclusion criteria at this stage, along with the reasons, in
the Characteristics of excluded studies table.
Data extraction and management
Two review authors extracted data from the included studies, independently and in duplicate, using a piloted data extraction form.
We resolved any disagreements through discussion. We contacted
study authors for clarification or missing information where necessary and possible.
We entered the following extracted data into the Characteristics
of included studies table.
• Study design, location, number of centres, recruitment
period, funding, experience level of clinician.
• Inclusion and exclusion criteria, age, gender, number of
participants randomised to each group, number of participants
evaluated.
• Details of the type of intervention/comparator, timing,
duration.
• Details of the outcomes reported, including method of
assessment, and time(s) assessed.
• Sample size calculations, any other notable details.
Assessment of risk of bias in included studies
Two review authors assessed the risk of bias of each included study,
independently and in duplicate, following the domain-based twopart tool described in the Cochrane Handbook for Systematic Reviews
of Interventions (Higgins 2011). We contacted study authors for
clarification or missing information where necessary and possible.
We compared our assessments and discussed and resolved any
inconsistencies between the review authors.
We assessed the following six domains of risk of bias for each
included study.
• Random sequence generation (selection bias).
• Allocation concealment (selection bias).
• Blinding of outcome assessment (detection bias).
• Incomplete outcome data (attrition bias).
• Selective reporting (reporting bias).
• Other bias.
We did not consider the blinding of participants and personnel
(performance bias) as the interventions being compared in all studies were different and it would not have been possible to blind
them as to which group they were allocated. Therefore, a risk of
performance bias is possible in all of the included studies. However, it should be possible for outcome assessors to be blinded if
measuring casts/models or radiographs or both, if the appliances
had been removed. Therefore, we focused on assessing the risk of
detection bias.
We completed a ’Risk of bias’ table for each included study. For
each of the above domains, we described what was reported to
have happened in the study and this formed the rationale for our
corresponding judgement of ’low risk’ of bias, ’high risk’ of bias
or ’unclear risk’ of bias for each domain.
We categorised overall risk of bias in any included study according
to the following.
Orthodontic treatment for posterior crossbites (Review)
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• Low risk of bias (plausible bias unlikely to seriously alter the
results) if all key domains were assessed as at low risk of bias.
• Unclear risk of bias (plausible bias that raises some doubt
about the results) if one or more key domains were assessed as at
unclear risk of bias.
• High risk of bias (plausible bias that seriously weakens
confidence in the results) if one or more key domains were
assessed as at high risk of bias.
1997; Higgins 2011), provided there were more than 10 studies
in a meta-analysis.
Data synthesis
We have presented the results of our risk of bias assessments graphically.
We only carried out a meta-analysis when studies of similar comparisons reported the same outcomes. We combined MDs for continuous outcomes, and RRs for dichotomous outcomes, using a
fixed-effect model when there were fewer than four studies, or a
random-effects model when there were four or more studies. We
summarised single-study comparisons in additional tables.
Measures of treatment effect
Subgroup analysis and investigation of heterogeneity
For dichotomous outcomes (e.g. posterior crossbite corrected or
not), we expressed the estimate of treatment effect as risk ratios
(RR) with 95% confidence intervals (CI). For continuous outcomes (e.g. width between the molars), we used the means and
standard deviations (SD) reported in the studies to calculate mean
differences (MD) with 95% CIs.
In future updates, if sufficient data are available for each comparison and outcome, we will conduct subgroup analyses according
to age, gender and the degree of severity of maxillary transversal
deficiency.
Dealing with missing data
Where possible, we attempted to contact the author(s) of studies to
obtain missing data or for clarification. We performed the analyses
using only the available data (ignoring missing data); however, we
intended to use methods for estimating missing SDs as described
in Section 7.7.3 of the Cochrane Handbook for Systematic Reviews
of Interventions (Higgins 2011), if appropriate. We did not use any
further statistical methods or carry out any further imputation to
account for missing data.
Assessment of heterogeneity
Where meta-analyses were performed, we assessed heterogeneity
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
heterogeneity statistically by means of a Chi2 test, where a P value <
0.1 indicated statistically significant heterogeneity. We quantified
heterogeneity using the I2 statistic. An approximate guide to the
interpretation of the I2 statistic given in the Cochrane Handbook
for Systematic Reviews of Interventions is: 0% to 40% might not be
important; 30% to 60% may represent moderate heterogeneity;
50% to 90% may represent substantial heterogeneity and 75% to
100% may represent considerable heterogeneity (Higgins 2011).
Sensitivity analysis
In future updates, if sufficient data are available for each comparison and outcome, we will assess the robustness of the results by
excluding studies at high and unclear risk of bias from the metaanalyses.
Presentation of main results
We produced ’Summary of findings’ tables following GRADE
methods (GRADE 2004), and using GRADEPro software. We
assessed the quality of the body of evidence by considering the
overall risk of bias of the included studies, the directness of the
evidence, the inconsistency of the results, the precision of the estimates and the risk of publication bias. We categorised the quality
of the body of evidence of each of the main outcomes for each
comparison as high, moderate, low or very low.
RESULTS
Description of studies
Results of the search
Assessment of reporting biases
We have already described the assessment of within-study reporting bias in the section Assessment of risk of bias in included studies.
In order to assess reporting biases that can occur when the publishing (or not publishing) of research findings is related to the results
(e.g. a study with a non-significant result may not be published),
we would have created a funnel plot to check for asymmetry (Egger
The electronic searches retrieved 779 references to studies. After
removing duplicates, this was reduced to 515. We obtained two
additional reports through other sources. After examination of
the titles and abstracts of these references, we discarded all but
33 with no further assessment. We obtained full-text copies of
these potentially relevant studies and we excluded 16 of them at
this stage (17 references). However, we did not record 14 (15
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9
references) of these in the table of excluded studies, as they were
clearly not eligible upon examining the full text. We linked two of
the remaining 16 articles together under a single study reference.
Therefore, 15 studies met the inclusion criteria for this review.
This process is presented as a flow chart in Figure 1.
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Figure 1. Study flow diagram.
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Included studies
Characteristics of the trial design and setting
Fifteen studies met the inclusion criteria and were included in this
review (see Characteristics of included studies tables).
All studies, by necessity, were of parallel design. Nine studies
(Asanza 1997, USA; Garib 2005, Brazil; Kilic 2008, Turkey;
Lagravere 2010, Canada; Lippold 2013, Germany; Martina 2012,
Italy; Mossaz-Joelson 1989, Switzerland; Oshagh 2012, Iran;
Ramoglu 2010, Turkey) were carried out in university orthodontics departments. One of these studies stated that the clinicians
were two specialist orthodontists (Lippold 2013), but in the remaining eight studies it was unclear who the clinicians undertaking the treatment were and what experience or qualifications they
had. There were three multicentre studies: one was carried out in
a general hospital and a university dental hospital in the UK by
experienced orthodontists (McNally 2005); one was carried out
in two public dental health service clinics and one university orthodontic department in Sweden by experienced general practitioners under the supervision of specialist orthodontists (Petrén
2008); and one study was carried out in three university orthodontic clinics and one private practice in Brazil, but it was unclear
who the clinicians undertaking the treatment were and what experience or qualifications they had (Oliveira 2004). One study took
place in a basic dental unit in Brazil, conducted by the local university, with treatment carried out by one specialist orthodontist
with over 10 years of experience (Godoy 2011). Participants in
another study were treated in a private orthodontic practice in the
USA by a board-certified orthodontist with 27 years of experience
(Lamparski 2003). The remaining study was carried out in Sweden by the public dental health service, but the experience of the
orthodontist was not reported (Thilander 1984).
Characteristics of the participants
Seven studies enrolled participants with either a unilateral or bilateral crossbite malocclusion (Garib 2005; Martina 2012; McNally
2005; Mossaz-Joelson 1989; Oliveira 2004; Petrén 2008; Ramoglu
2010), two studies included only participants with a unilateral
crossbite (Godoy 2011; Lippold 2013), two studies included only
participants with a bilateral crossbite (Kilic 2008; Oshagh 2012),
while the remaining four studies did not specify the type of crossbite that participants presented with at study entry (Asanza 1997;
Lagravere 2010; Lamparski 2003; Thilander 1984).
One study enrolled only children in the permanent dentition
(Garib 2005), two studies enrolled only children in the mixed
dentition (Godoy 2011; Petrén 2008), four studies enrolled children in either the mixed or permanent dentition (Lamparski 2003;
Martina 2012; Oliveira 2004; Ramoglu 2010), one study enrolled children in either the late deciduous or early mixed dentition (Lippold 2013), and seven studies did not state the stage of
dental development of the children at study entry (Asanza 1997;
Kilic 2008; Lagravere 2010; McNally 2005; Mossaz-Joelson 1989;
Oshagh 2012; Thilander 1984).
The age range of participants was from five to 16 years old with
variations between studies, but almost homogeneous within individual studies.
Characteristics of the interventions and comparisons
Six of the included studies evaluated two different types of fixed
appliances for rapid palatal expansion (Asanza 1997; Garib 2005;
Kilic 2008; Lagravere 2010; Lamparski 2003; Oliveira 2004), one
study compared two different fixed appliances for slow palatal
expansion (Mossaz-Joelson 1989), and two studies compared the
effects of fixed appliances used for differing rates of expansion
(Martina 2012; Ramoglu 2010).
Two studies compared a fixed appliance with a removable appliance for slow expansion (Godoy 2011; Petrén 2008), and the remaining studies evaluated other comparisons that were more difficult to classify (see below) (Lippold 2013; McNally 2005; Oshagh
2012; Thilander 1984).
See Appendix 1 for a description of appliances.
1. Fixed appliance with mid-palatal expansion
Rapid expansion
• Banded Hyrax (tooth borne) versus bonded Hyrax (tooth/
tissue borne) (Asanza 1997; Kilic 2008).
• Tooth-tissue borne Haas versus tooth borne Hyrax (Garib
2005; Oliveira 2004).
• Hyrax tooth-borne expander versus bone-anchored
expander (Lagravere 2010).
• Four-point banded (Hyrax) versus two-point banded
(Hyrax) (Lamparski 2003).
Slow expansion
• Bonded Minne versus banded Minne appliances
(Mossaz-Joelson 1989).
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Different rates of expansion
Characteristics of the outcomes
• Slow versus rapid expansion (two-band palatal expanders)
(Martina 2012).
• Semi-rapid versus rapid expansion (splint type tooth- and
tissue-borne modified bonded appliances) (Ramoglu 2010).
The primary outcome of this review, correction of the posterior
crossbite, was reported by three studies (Godoy 2011; Petrén 2008;
Thilander 1984). In 11 studies, the correction of crossbite is taken
for granted because it was the end point of the treatment and the
point at which activation of the appliances ceased (Asanza 1997;
Garib 2005; Kilic 2008; Lagravere 2010; Lamparski 2003; Lippold
2013; Martina 2012; McNally 2005; Oliveira 2004; Oshagh 2012;
Ramoglu 2010). In the remaining study, no data were provided
on whether the expansion obtained by these appliances did correct
the participants’ crossbite (Mossaz-Joelson 1989).
All included studies, with the exception of Thilander 1984, reported expansion of the upper jaw/teeth measured as changes
in the width between the molars or canines (or both). Two
studies assessed stability of crossbite correction (Godoy 2011;
Mossaz-Joelson 1989).
None of the included studies reported any of the other outcomes
of this review.
2. Fixed versus removable
Slow expansion
• Quad-helix versus expansion plate (Godoy 2011; Petrén
2008).
3. Other comparisons
• Early treatment with fixed bonded Hyrax appliance
followed by U-bow activator therapy versus no treatment
(Lippold 2013).
• Grinding - occlusal grinding in the primary dentition (aged
five years old) with/without an upper removable expansion
appliance in the mixed dentition versus no treatment (Thilander
1984).
Excluded studies
We excluded two studies from this review. One of these studies
was excluded because it included a subset of participants from one
of the included studies (Petrén 2008), plus other participants and
matched controls (Petrén 2011). The other study was excluded
after attempting to contact the authors because the participants
were only described as having maxillary deficiency, rather than
crossbite (Weissheimer 2011).
Risk of bias in included studies
Slow expansion
• Quad-helix plus multi-bracket versus expansion arch plus
multi-bracket (McNally 2005).
• Conventional mid-line expansion screw versus springloaded expansion screw (Oshagh 2012).
We have based our assessment of risk of bias on the reports of
the included studies because we could not access copies of the
study protocols. Where the reports were unclear on aspects of the
methodology, we attempted to contact the study authors to obtain
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
Sequence generation
Seven studies described adequate methods of sequence generation
and we judged them to be at low risk of bias for this domain: three
used a table of random numbers (Lagravere 2010; Oliveira 2004;
Oshagh 2012); two used block randomisation (Lippold 2013;
Martina 2012); one used a method of drawing lots (Godoy 2011);
and the remaining study used a similar method involving opaque
sealed envelopes (Petrén 2008).
One study used random number tables to allocate the first half of
the participants and then allocated the remaining half to receive
the alternative treatment to those in the initial allocation (McNally
2005). Therefore, only half the participants were truly randomly
allocated and we judged this study to be at high risk of bias for
this domain.
The remaining seven studies stated only that participants were
randomly allocated and we were unable to obtain further details
from the authors, so we judged these studies to be at unclear risk
of bias for this domain (Asanza 1997; Garib 2005; Kilic 2008;
Lamparski 2003; Mossaz-Joelson 1989; Ramoglu 2010; Thilander
1984).
Allocation concealment
Four studies described adequate methods of allocation concealment and we judged them to be at low risk of bias for this domain
(Godoy 2011; Martina 2012; Oliveira 2004; Petrén 2008).
The method of sequence generation carried out in one study, as
described above, would allow for the prediction of the allocation
of half of the participants, and therefore we judged this study to
be at high risk of bias for this domain (McNally 2005).
The remaining 10 studies did not mention any method of allocation concealment, so we judged these studies to be at unclear risk
of bias for this domain (Asanza 1997; Garib 2005; Kilic 2008;
Lagravere 2010; Lamparski 2003; Lippold 2013; Mossaz-Joelson
1989; Oshagh 2012; Ramoglu 2010; Thilander 1984).
Blinding of outcome assessment (detection bias)
We did not consider the blinding of participants and personnel
(performance bias) as the interventions being compared in all studies were different and it would not have been possible to blind
them as to which group they were allocated. Therefore, a risk of
performance bias is possible in all of the included studies.
However, it would have been possible for an independent blinded
person to perform the clinical, model and radiographic assessments. Therefore, we have focused on whether the included studies minimised the possible effects of detection bias.
Three studies clearly stated that the measurement of outcomes was
blinded, so we judged these studies to be at low risk of detection
bias (Godoy 2011; Martina 2012; Petrén 2008).
The remaining 12 studies did not mention blinding, even though
it was feasible that it could have occurred, and, therefore, we judged
these studies to be at unclear risk of bias for this domain.
Incomplete outcome data
We judged eight studies to be at low risk of attrition bias as they
either clearly described drop-outs (which were for similar reasons
and in similar numbers per group), or the numbers of participants
stated in the analyses were the same as those randomised, or an
intention-to-treat analysis included all randomised participants
(Asanza 1997; Godoy 2011; Kilic 2008; Lippold 2013; McNally
2005; Oliveira 2004; Petrén 2008; Ramoglu 2010).
One study clearly described the numbers and reasons for dropout but the high attrition rate (48% per group) meant that, if the
missing participants had higher mean scores in one group than
the other, as the attrition rate increased, so would over/understatement of the mean difference (Martina 2012). In another study, the
attrition rate was very different between the treated group (3%)
and the untreated group (18%) (Thilander 1984). Therefore, we
judged these two studies to be at high risk of attrition bias.
The remaining five studies did not report whether or not there
were any drop-outs and it was unclear how many participants were
included in the outcome assessment. Therefore, we judged these
studies to be at unclear risk of attrition bias (Garib 2005; Lagravere
2010; Lamparski 2003; Mossaz-Joelson 1989; Oshagh 2012).
Selective reporting
Eleven studies reported all outcome measures described in the corresponding methods sections in full and we assessed them as being
at low risk of reporting bias (Garib 2005; Godoy 2011; Kilic 2008;
Lagravere 2010; Martina 2012; McNally 2005; Mossaz-Joelson
1989; Oliveira 2004; Petrén 2008; Ramoglu 2010; Thilander
1984).
We judged the remaining four studies to be at high risk of reporting
bias for the following reasons: no measure of variance reported
(Asanza 1997; Lippold 2013); one outcome was not reported by
group and the other was reported without a measure of variance
(Lamparski 2003); and the results were so inadequately reported
that we were unable to use any data (Oshagh 2012).
Other potential sources of bias
In one study, there were imbalances between the treatment groups
in terms of numbers of participants and gender, possibly indicating
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a problem with the randomisation (Oshagh 2012). We assessed
this study as being at high risk of bias for this domain. We did not
identify any other potential sources of bias in any of the remaining
14 studies and, therefore, we judged them to be at low risk of bias
for this domain.
completion of the expansion phase, but the difference was not
statistically significant (Analysis 1.1). As the sample size was so
small, and there was considerable heterogeneity (I2 = 94%), this
result should be interpreted with caution.
No other outcomes of the review were assessed in this comparison.
Overall risk of bias
Hyrax tooth-borne expander versus bone-anchored expander
• Two studies were at low risk of bias (Godoy 2011; Petrén
2008).
• Seven studies were at high risk of bias (Asanza 1997;
Lamparski 2003; Lippold 2013; Martina 2012; McNally 2005;
Oshagh 2012; Thilander 1984).
• Six studies were at unclear risk of bias (Garib 2005; Kilic
2008; Lagravere 2010; Mossaz-Joelson 1989; Oliveira 2004;
Ramoglu 2010).
One study at unclear risk of bias, analysing no more than 41
participants (unclear attrition), assessed molar expansion at six and
12 months after completion of the expansion phase (Lagravere
2010). There were no statistically significant differences at either
time point (Additional Table 1).
No other outcomes of the review were assessed in this comparison.
Effects of interventions
Four-point banded (Hyrax) versus two-point banded (Hyrax)
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
compared with removable appliances for treating posterior
crossbites; Summary of findings 3 Other comparisons for treating
posterior crossbites
See Appendix 1 for a description of appliances.
One study at high risk of bias, analysing no more than 30 participants (unclear attrition), assessed molar and canine expansion at
three months after completion of the expansion phase (Lamparski
2003). There were no statistically significant differences for either
outcome (Additional Table 1).
No other outcomes of the review were assessed in this comparison.
1. Fixed appliance with mid-palatal expansion
Slow expansion
Rapid expansion
Bonded Minne versus banded Minne appliances
Banded Hyrax (tooth borne) versus bonded Hyrax
(tooth/tissue borne)
We included two studies, one at unclear and one at high risk of bias,
analysing 53 participants, in this comparison (Asanza 1997; Kilic
2008). Due to problems with reporting of the data in one study
(Asanza 1997), we were unable to combine the results in a metaanalysis. Both studies assessed molar expansion and reported no
statistically significant difference (Table 1). One study measured
the outcomes three months after completion of the expansion
phase (Asanza 1997), while the other study measured it one week
after completion of the expansion phase (Kilic 2008).
No other outcomes of the review were assessed in this comparison.
One study at unclear risk of bias, analysing no more than 10 participants (unclear attrition), assessed molar and canine expansion
seven to 15 weeks after the start of treatment, and stability (relapse
of molar and canine expansion) 24 weeks after completion of the
expansion phase (Mossaz-Joelson 1989). There were no statistically significant differences for any outcome (Additional Table 1).
No other outcomes of the review were assessed in this comparison.
Different rates of expansion
Slow versus rapid expansion (two-band palatal expanders)
Tooth-tissue borne Haas versus tooth borne Hyrax
Two studies, both at unclear risk of bias, analysing 27 participants,
assessed molar expansion (Garib 2005; Oliveira 2004). The pooled
mean difference (MD) was 0.7 mm (95% confidence interval (CI)
-0.25 to 1.66) in favour of Haas appliances at three months after
One study at high risk of bias, analysing 26 participants, assessed
molar expansion seven months after the start of treatment (Martina
2012). There was no statistically significant difference (Additional
Table 1).
No other outcomes of the review were assessed in this comparison.
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Semi-rapid versus rapid expansion (splint type tooth- and
tissue-borne modified bonded appliances)
One study at unclear risk of bias, analysing 35 participants, assessed molar and canine expansion (Ramoglu 2010). There were
no statistically significant differences for either outcome (Additional Table 1).
No other outcomes of the review were assessed in this comparison.
No other outcomes of the review were assessed in this comparison.
One study also compared both appliances in this comparison
against composite onlays (Petrén 2008). There were statistically
significant differences for the outcomes crossbite correction, molar expansion and canine expansion in favour of the fixed and removable appliances (Additional Table 2).
3. Other comparisons
2. Fixed versus removable
Slow expansion
Quad-helix versus expansion plate
We included two studies, both at low risk of bias, analysing 96
participants, in this comparison (Godoy 2011; Petrén 2008). The
two studies included children in the early mixed dentition (aged
eight to 10 years). For the outcome crossbite correction, the pooled
risk ratio (RR) suggests that 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) (Analysis 2.1). The 95%
CI indicates that the true effect estimate lies somewhere between
a 4% and 37% better correction rate for quad-helix appliances.
However, the sample size was small and there was substantial heterogeneity (I2 = 68%), so this result should be interpreted with
caution, and the results may not be the same in the permanent
dentition.
For the outcome molar expansion, the pooled MD suggests that
quad-helix appliances can achieve 1.15 mm more expansion than
expansion plates (MD 1.15 mm; 95% CI 0.40 to 1.90) (Analysis
2.2). The 95% CI indicates that the true effect estimate lies somewhere between 0.4 mm and 1.9 mm in favour of quad-helix appliances. While there was no heterogeneity (I2 = 0%), the result
should be interpreted with caution as the sample size was small
and the follow-up times differed between the studies.
For the outcome canine expansion, the pooled MD was 0.19 mm
(95% CI -0.47 to 0.85) in favour of quad-helix appliances, but
the difference was not statistically significant (Analysis 2.3). Due
to considerable heterogeneity (I2 = 91%), small sample size and
different follow-up times, the result should be interpreted with
caution.
One study also assessed the stability of crossbite correction (relapse 12 months after correction) (Godoy 2011). There was no
statistically significant difference (Additional Table 2).
Early treatment with fixed bonded Hyrax appliance followed
by U-bow activator therapy versus no treatment
One study at high risk of bias, analysing 66 participants, assessed
molar and canine expansion 12 months after the start of treatment
(Lippold 2013). Statistically significant differences were reported
for both outcomes in favour of treatment (Additional Table 3).
No other outcomes of the review were assessed in this comparison.
Grinding - occlusal grinding in the primary dentition (at age
five years) with/without subsequent upper removable
expansion appliance in the mixed dentition versus no
treatment
One study at high risk of bias, analysing 61 participants, assessed
crossbite correction after one, two, five and eight years (Thilander
1984). A statistically significant difference was reported in favour
of treatment (Additional Table 3).
Slow expansion
Quad-helix plus multi-bracket versus expansion arch plus
multi-bracket
One study at high risk of bias assessed molar (analysing 55 participants) and canine (analysing 52 participants - lower number
due to unerupted canines) expansion 12 weeks after the start of
treatment (McNally 2005). There were no statistically significant
differences for either outcome (Additional Table 3).
Conventional mid-line expansion screw versus spring-loaded
expansion screw
One study at high risk of bias assessed molar and canine expansion
but we were unable to extract any data from the study report
(Oshagh 2012).
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A D D I T I O N A L S U M M A R Y O F F I N D I N G S [Explanation]
Fixed appliances compared with removable appliances for treating posterior crossbites
Patient or population: Children with posterior crossbites (adults would be included in the review but no studies with adults were found)
Settings: Public Dental Health Service and university orthodontic/dental clinics
Intervention: Fixed appliance
Comparison: Removable appliance
Outcomes
Illustrative comparative risks* (95% CI)
Assumed risk
Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments
RR 1.2 (1.04 to 1.37)
96
(2)
⊕⊕
low
2 studies at low risk of
bias, but with serious inconsistency (I2 = 68%)
and imprecision due to
low sample size
Corresponding risk
Removable
slow Fixed - slow expansion
expansion (expansion (quad-helix)
plate)
Crossbite correction
833 per 1000
(Follow-up after retention
period, therefore, it was
variable)
1000 per 1000
(867 to 1000)
Molar expansion
(mm)
(Follow-up after retention
period, therefore, it was
variable)
The mean expansion
ranged across the removable appliance groups
from 3.09 to 3.5 mm
The mean expansion in N/A
the fixed appliance group
was
1.15 mm higher
(0.4 to 1.9 higher)
96
(2)
⊕⊕⊕
moderate
2 studies at low risk of
bias, but with imprecision
due to low sample size
Canine expansion
(mm)
(Follow-up after retention
period, therefore it was
variable)
The mean expansion
ranged across the removable appliance groups
from 1.43 to 2.7 mm
The mean expansion in N/A
the fixed appliance group
was
0.19 mm higher
(0.47 lower to 0.85
higher)
96
(2)
⊕⊕
low
2 studies at low risk of
bias, but with serious inconsistency (I2 = 91%)
and imprecision due to
low sample size
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N/A
N/A
N/A
N/A
N/A
N/A
1 of the 2 studies in this
comparison also measured stability of crossbite correction (relapse
12 months after correction). No statistically significant difference was
found (Additional Table 2)
The other study also compared the fixed and removable appliances to
composite onlays for
crossbite correction, molar expansion and canine expansion. All results were statistically
significant in favour of
fixed and removable appliances (Additional Table
2)
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.
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.
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Other comparisons for treating posterior crossbites
Patient or population: Children with posterior crossbites (adults would be included in the review but no studies with adults were found)
Settings: Public Dental Health Service and university/hospital orthodontic/dental clinics
Outcomes
N/A
Illustrative comparative risks (95% CI)
Assumed risk
Corresponding risk
Group A
Group B
N/A
N/A
Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments
N/A
N/A
N/A
The comparisons were all
single studies (Additional
Table 3). The quality of
the evidence (GRADE) for
all comparisons and outcomes in Additional Table
3 is ⊕ very low (all
at high risk of bias with imprecision due to low sample sizes)
• 1 study compared a
removable appliance with
spring-loaded screw
against a conventional
screw but the results were
inadequately reported
• 1 study compared
quad-helix plus multibracket against expansion
arch plus multi-bracket for
molar/canine expansion
with no statistically
significant results
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• The final 2 studies
showed statistically
significant results against
no treatment for fixed
bonded Hyrax appliance
followed by U-bow
activator (molar/canine
expansion), and for
grinding or grinding plus
expansion plate (crossbite
correction)
GRADE Working Group grades of evidence
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.
21
DISCUSSION
and expansion arch plus multi-bracket. Finally, there was no evidence regarding the comparison of removable appliances with either spring-loaded or conventional screws.
Summary of main results
The objective of this review was to evaluate the effects of different
orthodontic treatments for correcting posterior crossbites. We included 15 randomised controlled trials (RCTs) that met the inclusion criteria for this review. We assessed the body of evidence for
each comparison and outcome using GRADE, which takes into
account the risk of bias of the included studies, the directness of
the evidence, the inconsistency of the results, the precision of the
estimates and the risk of publication bias (GRADE 2004). The
body of evidence for all comparisons and outcomes in this review
was very small.
Fixed appliance with mid-palatal expansion
The body of evidence for all comparisons and outcomes in this
group was rated as very low quality (Summary of findings for the
main comparison). In all cases, the evidence was insufficient to
determine a difference between any one type of appliance and
another for any outcome.
Fixed versus removable appliance
We found low-quality evidence to suggest that crossbite correction
is more successful when using a fixed quad-helix appliance than
when using a removable expansion plate for slow maxillary expansion (Summary of findings 2). For the same comparison, moderate-quality evidence suggested that molar expansion is greater
for fixed quad-helix appliances, and further low-quality evidence
was insufficient to determine a difference in canine expansion. It
should be noted that the two studies included children in the early
mixed dentition (aged eight to 10 years) and the results may not
be the same for people in the permanent dentition. There was
also very low quality evidence that was insufficient to determine a
difference in stability of crossbite correction between fixed quadhelix appliances and removable expansion plates. Further very low
quality evidence suggested that fixed quad-helix appliances and
removable expansion plates are superior to composite onlays for
crossbite correction, molar expansion and canine expansion.
Others interventions
We found very low quality evidence to suggest that both tooth
grinding, with or without an expansion plate and fixed bonded
Hyrax followed by U-bow activator are superior to no treatment
for the outcomes crossbite correction and molar/canine correction respectively (Summary of findings 3). We also found very low
quality evidence that was insufficient to determine a difference in
molar or canine expansion between quad-helix plus multi-bracket
Overall completeness and applicability of
evidence
The studies identified in this review are insufficient to address the
question of what is the best treatment for posterior crossbites. Although we were able to include 15 studies, there were many different comparisons of appliances or other treatments and, therefore,
there was minimal pooling of data. This is unfortunate as one of
the advantages of a systematic review is the ability to pool multiple
studies in order to increase the power to detect a difference confidently, and thus to inform clinical practice better. Furthermore,
there were very limited data available for the outcome stability
of crossbite correction, and no studies assessed signs and symptoms of temporomandibular joint dysfunction/respiratory disease
or quality of life. However, this was perhaps because all the studies included only children. This highlights another shortcoming
in the overall completeness of the evidence, which is that there is
no evidence on orthodontic treatments for adults with posterior
crossbites. The lack of evidence regarding adults in this review is
probably because the majority of studies on adults with a posterior crossbite compare orthodontic treatments with orthodonticsurgical interventions, but we excluded surgical treatments from
this review.
Quality of the evidence
The body of evidence identified does not allow for any robust
conclusions to be made regarding the objective of this review. The
sample sizes were consistently small (as low as eight participants),
and this fact, combined with the lack of pooling of data in metaanalyses, meant that the power to detect statistically and clinically significant differences, with confidence, was limited. Another
problem was inconsistency as three of the four meta-analyses displayed statistically significant heterogeneity. While there were two
low risk of bias studies that we were able to pool, the results cannot be relied upon due to the problems already mentioned. The
remaining studies were either at high risk of bias (seven studies) or
the risk of bias was unclear (six studies). Most of the comparisons
included in the review were assessed by very small single studies,
which do not allow any conclusions to be drawn as to the effects
of the interventions studied.
Potential biases in the review process
We made every attempt to limit bias in the review process by ensuring a comprehensive search for potentially eligible studies. The
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
22
authors’ independent assessments of study eligibility and subsequent data extraction and risk of bias assessment minimised the
potential for additional bias beyond that detailed in the ’Risk of
bias’ tables in the Characteristics of included studies section. The
incompleteness of some of the reports and our inability to obtain
clarification of certain trial details or to resolve ambiguities in the
reports may have contributed to some bias in their assessment,
but where these conditions applied this was explicitly stated in the
text of our review. Finally, we attempted to minimise bias further
by changing our inclusion criteria to only include RCTs which,
when performed to a high standard, should be less biased than
other study designs.
Agreements and disagreements with other
studies or reviews
Another systematic review of maxillary expansion arches for treating crossbites included studies published from 1999 to 2011
(Zuccati 2013). The authors of the review assessed the studies using the Consolidated Standards of Reporting Trials (CONSORT)
statement. In similarity with our review, they argued that there
was substantial evidence of bias, which reduced the quality of the
evidence; the randomisation process was poorly described and loss
to follow-up was unclear in many of the included studies. Their
review also called for future trials to be carefully planned and reported using universal guidelines.
AUTHORS’ CONCLUSIONS
Implications for research
More randomised controlled trials are required to address the question of what is the best treatment for posterior crossbites in children, adolescents and adults. The studies should be large enough
to detect a difference, if one exists, and should assess appropriate
outcomes. We believe that ’correction of crossbite’ needs to be the
primary outcome for all studies addressing this research question.
In studies where all the crossbites were corrected (as with most
studies in this review), ’time to correction’ and ’pain’ would be of
increased importance as outcomes.
High-quality work should be carried out to develop core outcome
sets for orthodontics/areas of orthodontics. Such work should be
carried out in association with the COMET (Core Outcome Measures in Effectiveness Trials) Initiative (www.comet-initiative.org),
using robust methodology suggested by those working with the
COMET Initiative so far (Williamson 2012). These core outcome
sets should subsequently be the minimum set of outcomes that
are measured in all clinical trials and systematic reviews (including
this Cochrane review).
Future randomised controlled trials must be well designed, well
conducted and adequately delivered with subsequent reporting,
including high-quality descriptions of all aspects of methodology. Reporting should conform to the Consolidated Standards of Reporting Trials (CONSORT) statement (www.consortstatement.org), which will enable appraisal and interpretation of
results, and accurate judgements to be made about the risk of bias
and the overall quality of the evidence. Although it is uncertain
whether reported quality mirrors actual study conduct, it is noteworthy that studies with unclear methodology have been shown
to produce biased estimates of treatment effects (Schulz 1995).
Implications for practice
There is a very small body of low- to moderate-quality evidence
to suggest that fixed quad-helix appliances may be more successful
than removable expansion plates at correcting posterior crossbites
and expanding the inter-molar width in children with early mixed
dentition (aged eight to 10 years). The remaining evidence that
we found was of very low quality and was insufficient to allow the
conclusion that any one intervention is better than another for
any of the outcomes in this review.
ACKNOWLEDGEMENTS
The review authors would like to thank the Cochrane Oral Health
Group and referees for their help in conducting this systematic
review.
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
23
REFERENCES
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References to studies excluded from this review
Petrén 2011 {published and unpublished data}
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Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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Subtelny JD. Oral respiration: facial maldevelopment and
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Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
25
Williamson 2012
Williamson PR, Altman DG, Blazeby JM, Clarke M,
Devane D, Gargon E, et al. Developing core outcome sets
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References to other published versions of this review
Harrison 2001
Harrison JE, Ashby D. Orthodontic treatment for posterior
crossbites. Cochrane Database of Systematic Reviews 2001,
Issue 1. [DOI: 10.1002/14651858.CD000979]
∗
Indicates the major publication for the study
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
26
CHARACTERISTICS OF STUDIES
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 Center, 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 encased 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
Notes
No sample size calculation reported
Risk of bias
Bias
Authors’ judgement
Random sequence generation (selection Unclear risk
bias)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Support for judgement
Quote: “Appliances were randomly assigned”
Comment: Insufficient information on the
method of sequence generation
27
Asanza 1997
(Continued)
Allocation concealment (selection bias)
Unclear risk
Quote: “Appliances were randomly assigned”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
Not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Low risk
No drop-outs reported. Data in Table 5 implied that there were no drop-outs
Selective reporting (reporting bias)
High risk
No measures of variance were reported, so
we were unable to analyse the data
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
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
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
28
Garib 2005
(Continued)
Notes
Casual and systematic errors were calculated comparing the first measurement with
Dahlberg’s formula 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 generation (selection Unclear risk
bias)
Quote: “...sample of eight patients, who
were randomly assigned to two groups”
Comment: Insufficient information on the
method of sequence generation
Allocation concealment (selection bias)
Unclear risk
Quote: “...sample of eight patients, who
were randomly assigned to two groups”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible
to blind outcome assessors as the appliances
were removed before final measurements
were made. However, it was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk
No indication of whether or not there were
any drop-outs. Unclear how many participants were included in the outcome assessment
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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
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 anterioposterior cephalometric radiographs
Exclusion criteria: Sucking habits, previous orthodontic treatment, Class III malocclu-
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
29
Godoy 2011
(Continued)
sion
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). Appliance 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
Random sequence generation (selection Low risk
bias)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Support for judgement
Quote: “For randomization, numbers were
randomly drawn from a plastic bag. 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 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,
30
Godoy 2011
(Continued)
the second one to the EP [expansion plate]
group, the third one to the untreated group,
the fourth to the QDH group...”
Allocation concealment (selection bias)
Low risk
The method described above would not allow anybody involved in the study to know
their treatment allocation until they had
been allocated
Blinding of outcome assessment (detection Low risk
bias)
All outcomes
Quote: “Palatal expansion and crossbite
correction were measured on the study casts
by 1 masked investigator... The investigator was unaware of the type of appliance
used by the patient and the length of treatment (pretreatment, after expansion, after
6 months of retention, or 6 months after
removal of the retention plate)”
Incomplete outcome data (attrition bias)
All outcomes
Low risk
“Dropouts and treatments not completed
within 12 months were classified as unsuccessful”
Intention-to-treat analysis included all randomised participants
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
31
Kilic 2008
(Continued)
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)
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 generation (selection Unclear risk
bias)
Quote: “Randomly assigned to two groups”
Comment: Insufficient information on the
method of sequence generation
Allocation concealment (selection bias)
Unclear risk
Quote: “Randomly assigned to two groups”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It may have been possible to blind outcome
assessors if the appliances were removed before final measurements were made. However, this was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Low risk
No drop-outs reported. Numbers of participants per group reported in the results
tables matches the numbers that were randomised
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
Other bias
Low risk
No other sources of bias identified
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
32
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)
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 custommilled 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 left
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 generation (selection Low risk
bias)
Quote: “Subjects were randomized into the
groups by using a random numbers generated list”
Allocation concealment (selection bias)
Unclear risk
Quote: “Subjects were randomized into the
groups by using a random numbers generated list”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible
to blind outcome assessors as the appliances
were removed before final measurements
Orthodontic treatment for posterior crossbites (Review)
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Lagravere 2010
(Continued)
were made. However, it was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk
No indication of whether or not there were
any drop-outs. Unclear how many participants were included in the outcome assessment
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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
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 cemented 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
Random sequence generation (selection Unclear risk
bias)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Support for judgement
Quote: “The subjects were randomly assigned”
34
Lamparski 2003
(Continued)
Comment: Insufficient information on the
method of sequence generation
Allocation concealment (selection bias)
Unclear risk
Quote: “The subjects were randomly assigned”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible
to blind outcome assessors as the appliances
were removed before final measurements
were made. However, it was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk
No indication of whether or not there were
any drop-outs. Unclear how many participants were included in the outcome assessment
Selective reporting (reporting bias)
High risk
Outcomes planned in the methods section were reported in the results. However,
means and SDs in each group were not reported
Other bias
Low risk
No other sources of bias identified
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; cleft lip
and palate; general impairments; 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
Orthodontic treatment for posterior crossbites (Review)
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35
Lippold 2013
(Continued)
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 generation (selection Low risk
bias)
Quote: “Block randomisation with a block
length of 20 and an allocation ratio of 1:1”
Allocation concealment (selection bias)
Unclear risk
Quote: “Block randomisation with a block
length of 20 and an allocation ratio of 1:1”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible to blind outcome assessors as the appliances could have been removed before final measurements were made. 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 (attrition bias)
All outcomes
Low risk
Numbers of drop-outs and reasons were
clearly described in a study workflow (Figure 1), and were sufficiently similar in each
group
Selective reporting (reporting bias)
High risk
No SD for mean change from baseline reported
Other bias
Low risk
No other sources of bias identified
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
36
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 lightcure 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
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 generation (selection Low risk
bias)
Quote: “Balanced block randomisation using gender as a stratifying factor”
Allocation concealment (selection bias)
Quote: “A single operator allocated the patients by means of a custom-made Java
script and was responsible for the allocation concealment, that is, the allocation was
Low risk
Orthodontic treatment for posterior crossbites (Review)
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37
Martina 2012
(Continued)
disclosed only when a new patient was enrolled in the trial”
Blinding of outcome assessment (detection Low risk
bias)
All outcomes
Measurements were made by a single operator blinded to participant allocation
Incomplete outcome data (attrition bias)
All outcomes
High risk
Numbers of drop-outs and reasons were
clearly described in a study workflow (Figure 4), and were similar. However, dropout
rate was very high (Gp A: 48%; 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 (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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)
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
Orthodontic treatment for posterior crossbites (Review)
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38
McNally 2005
(Continued)
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 generation (selection High risk
bias)
Quote: “Using random number tables the
first 30 participants were allocated 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 (selection bias)
Quote: “Using random number tables the
first 30 participants were allocated 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
High risk
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
Quote: “The group of the participant was
obvious from the model since the imprint of each type of appliance could be
seen. However, since all measurements 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 (attrition bias)
All outcomes
Low risk
Numbers of drop-outs and reasons are
clearly described in a study workflow (Figure 4), and are sufficiently similar in each
group
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
Other bias
Low risk
No other sources of bias identified
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
39
Mossaz-Joelson 1989
Methods
Study design: Reclassified as RCT following correspondence (2 arms)
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 generation (selection Unclear risk
bias)
From correspondence with study authors:
“...randomly divided into two groups...”
Comment: Insufficient information on the
method of sequence generation
Allocation concealment (selection bias)
From correspondence with study authors:
“...randomly divided into two groups...”
Comment: Not mentioned
Unclear risk
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
40
Mossaz-Joelson 1989
(Continued)
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible
to blind outcome assessors as the appliances
were removed before final measurements
were made. However, it was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk
No indication of whether or not there were
any drop-outs. Unclear how many children
were included in the outcome assessment
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
41
Oliveira 2004
(Continued)
Bias
Authors’ judgement
Support for judgement
Random sequence generation (selection Low risk
bias)
Quote: “Randomization was carried out by
using a table of random numbers”
Allocation concealment (selection bias)
Quote: “A staff member in the clinic was
informed about every new patient 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
Low risk
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible
to blind outcome assessors as the appliances
were removed before final measurements
were made. However, it was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Low risk
No drop-outs reported. Numbers of participants per group reported in the results
tables matched the numbers that were randomised
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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 auxiliary component, cleft 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
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
42
Oshagh 2012
(Continued)
Interventions
Comparison: (Removable split acrylic plates) (slow expansion) conventional midline 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
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 generation (selection Low risk
bias)
Quote: “Randomization was accomplished
by a randomization table”
Allocation concealment (selection bias)
Unclear risk
Quote: “Randomization was accomplished
by a randomization table”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It appears that it would have been possible to blind outcome assessors as the appliances were removed before casts were made.
However, it was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk
No indication of whether or not there were
any drop-outs. Unclear how many children
were included in the outcome assessment
Selective reporting (reporting bias)
High risk
Poor reporting of results. Only the overall
mean monthly changes were reported. 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
Orthodontic treatment for posterior crossbites (Review)
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43
Petrén 2008
Methods
Study design: RCT (4 arms)
Location: Public Dental Health Service, Skane County Council, Sweden, and the Department of Orthodontics, 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
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 quadhelix 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 dimension 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 target was met
Risk of bias
Orthodontic treatment for posterior crossbites (Review)
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44
Petrén 2008
(Continued)
Bias
Authors’ judgement
Support for judgement
Random sequence generation (selection Low risk
bias)
Quote: “The subjects were randomized as
follows: 4 opaque envelopes were 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 (selection bias)
Low risk
Quote: “The envelope was in the care of 1
investigator...who was contacted and randomly extracted a note and informed the
dentist which treatment strategy to use”
Blinding of outcome assessment (detection Low risk
bias)
All outcomes
Quote: “Measurements were blinded; the
examiner was unaware of which treatment
the patients had received or which models
were taken at T0 and T1”
Incomplete outcome data (attrition bias)
All outcomes
Low risk
Quote: “Data on all patients were analyzed
on an intention-to-treat (ITT) basis... all
patients, successful or not, were included in
the final analysis” and “all patients finished
the trial (Fig 5)”
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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; eruption of the first permanent molars
Exclusion criteria: Sagittal skeletal problem; more than 1 missing maxillary tooth in the
right and left sides of the dentition
Gp A: mean age 8.63 years (SD 1.09); M/F 7/11
Orthodontic treatment for posterior crossbites (Review)
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Ramoglu 2010
(Continued)
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
Bias
Authors’ judgement
Support for judgement
Random sequence generation (selection Unclear risk
bias)
Quote: “The subjects were randomly divided into two groups”
Comment: Insufficient information on the
method of sequence generation
Allocation concealment (selection bias)
Unclear risk
Quote: “The subjects were randomly divided into two groups”
Comment: Not mentioned
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
It may have been possible to blind outcome
assessors if the appliances were removed before final measurements were made. However, this was not mentioned
Incomplete outcome data (attrition bias)
All outcomes
Low risk
No drop-outs reported. Numbers of participants per group reported in the results
tables matches the numbers that were randomised
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
Other bias
Low risk
No other sources of bias identified
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
46
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
Outcomes
Correction of crossbite
Notes
No sample size calculation reported
Risk of bias
Bias
Authors’ judgement
Support for judgement
Random sequence generation (selection Unclear risk
bias)
Quote: “68 children...were randomly divided into two groups”
Comment: Insufficient information on the
method of sequence generation
Allocation concealment (selection bias)
Quote: “68 children...were randomly divided into two groups”
Comment: Not mentioned
Unclear risk
Blinding of outcome assessment (detection Unclear risk
bias)
All outcomes
Not mentioned
Incomplete outcome data (attrition bias)
All outcomes
The dropout rate was very different between the treated group (3%) and the
untreated group (18%). Reasons reported
were lack of interest in the untreated group
and relocation from the town
High risk
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
47
Thilander 1984
(Continued)
Selective reporting (reporting bias)
Low risk
Outcome measures described in the methods section were reported in full
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
Orthodontic treatment for posterior crossbites (Review)
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48
DATA AND ANALYSES
Comparison 1. Fixed rapid (Haas) versus fixed rapid (Hyrax)
Outcome or subgroup title
1 Molar expansion (3 months after
completion of expansion phase)
No. of
studies
No. of
participants
2
27
Statistical method
Effect size
Mean Difference (IV, Fixed, 95% CI)
0.70 [-0.25, 1.66]
Comparison 2. Fixed slow (quad-helix) versus removable slow (expansion plate)
Outcome or subgroup title
1 Crossbite correction
2 Molar expansion
3 Canine expansion
No. of
studies
No. of
participants
2
2
2
96
96
96
Statistical method
Effect size
Risk Ratio (M-H, Fixed, 95% CI)
Mean Difference (IV, Fixed, 95% CI)
Mean Difference (IV, Fixed, 95% CI)
1.20 [1.04, 1.37]
1.15 [0.40, 1.90]
0.19 [-0.47, 0.85]
Analysis 1.1. Comparison 1 Fixed rapid (Haas) versus fixed rapid (Hyrax), Outcome 1 Molar expansion (3
months after completion of expansion phase).
Review:
Orthodontic treatment for posterior crossbites
Comparison: 1 Fixed rapid (Haas) versus fixed rapid (Hyrax)
Outcome: 1 Molar expansion (3 months after completion of expansion phase)
Study or subgroup
Haas
Mean
Difference
Hyrax
Weight
Mean
Difference
N
Mean(SD)[mm]
N
Mean(SD)[mm]
Garib 2005
4
6.5 (1)
4
6.7 (0.4)
81.8 %
-0.20 [ -1.26, 0.86 ]
Oliveira 2004
9
8.49 (2.33)
10
3.73 (2.64)
18.2 %
4.76 [ 2.53, 6.99 ]
100.0 %
0.70 [ -0.25, 1.66 ]
Total (95% CI)
13
IV,Fixed,95% CI
IV,Fixed,95% CI
14
Heterogeneity: Chi2 = 15.47, df = 1 (P = 0.00008); I2 =94%
Test for overall effect: Z = 1.45 (P = 0.15)
Test for subgroup differences: Not applicable
-20
-10
Favours Hyrax
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
0
10
20
Favours Haas
49
Analysis 2.1. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 1
Crossbite correction.
Review:
Orthodontic treatment for posterior crossbites
Comparison: 2 Fixed slow (quad-helix) versus removable slow (expansion plate)
Outcome: 1 Crossbite correction
Study or subgroup
Quad-helix
Expansion plate
n/N
n/N
Godoy 2011
33/33
30/33
74.4 %
1.10 [ 0.97, 1.24 ]
Petr n 2008
15/15
10/15
25.6 %
1.48 [ 1.02, 2.13 ]
48
48
100.0 %
1.20 [ 1.04, 1.37 ]
Total (95% CI)
Risk Ratio
Weight
Risk Ratio
M-H,Fixed,95% CI
M-H,Fixed,95% CI
Total events: 48 (Quad-helix), 40 (Expansion plate)
Heterogeneity: Chi2 = 3.15, df = 1 (P = 0.08); I2 =68%
Test for overall effect: Z = 2.58 (P = 0.0097)
Test for subgroup differences: Not applicable
0.1 0.2
0.5
1
Favours expansion plate
2
5
10
Favours quad-helix
Analysis 2.2. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 2
Molar expansion.
Review:
Orthodontic treatment for posterior crossbites
Comparison: 2 Fixed slow (quad-helix) versus removable slow (expansion plate)
Outcome: 2 Molar expansion
Study or subgroup
Quad-helix
Mean
Difference
Expansion plate
Weight
IV,Fixed,95% CI
Mean
Difference
N
Mean(SD)[mm]
N
Mean(SD)[mm]
IV,Fixed,95% CI
Godoy 2011
33
4.31 (2.4)
33
3.09 (2.4)
42.0 %
1.22 [ 0.06, 2.38 ]
Petr n 2008
15
4.6 (1.19)
15
3.5 (1.54)
58.0 %
1.10 [ 0.12, 2.08 ]
Total (95% CI)
48
100.0 % 1.15 [ 0.40, 1.90 ]
48
Heterogeneity: Chi2 = 0.02, df = 1 (P = 0.88); I2 =0.0%
Test for overall effect: Z = 3.01 (P = 0.0027)
Test for subgroup differences: Not applicable
-2
-1
Favours expansion plate
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
0
1
2
Favours quad-helix
50
Analysis 2.3. Comparison 2 Fixed slow (quad-helix) versus removable slow (expansion plate), Outcome 3
Canine expansion.
Review:
Orthodontic treatment for posterior crossbites
Comparison: 2 Fixed slow (quad-helix) versus removable slow (expansion plate)
Outcome: 3 Canine expansion
Study or subgroup
Quad-helix
Mean
Difference
Expansion plate
Weight
Mean
Difference
N
Mean(SD)[mm]
N
Mean(SD)[mm]
Godoy 2011
33
2.96 (2.48)
33
1.43 (1.78)
IV,Fixed,95% CI
40.1 %
1.53 [ 0.49, 2.57 ]
IV,Fixed,95% CI
Petr n 2008
15
2 (1.18)
15
2.7 (1.2)
59.9 %
-0.70 [ -1.55, 0.15 ]
Total (95% CI)
48
48
100.0 % 0.19 [ -0.47, 0.85 ]
Heterogeneity: Chi2 = 10.55, df = 1 (P = 0.001); I2 =91%
Test for overall effect: Z = 0.58 (P = 0.56)
Test for subgroup differences: Not applicable
-2
-1
0
Favours expansion plate
1
2
Favours quad-helix
ADDITIONAL TABLES
Table 1. Fixed versus fixed with mid-palatal expansion (single study comparisons)
Study
Outcome
Group A
Group B
Asanza 1997
Molar expansion (3 Hyrax banded: Mean 6 Hyrax bonded: Mean 5.9 P value = NS (as reported
months after completion mm (min 4.3 mm - max mm (min 3.2 mm - max in the study - no SD reof expansion phase)
7.2 mm)
7.7 mm)
ported)
Kilic 2008
Molar expansion (1 week Hyrax banded: Mean 7. Hyrax bonded: Mean 7. MD 0.36 (95% CI -0.72
after completion of ex- 67 mm (SD 1.99)
31 mm (SD 1.45)
to 1.44)
pansion phase)
P value = 0.51
Lagravere 2010
Molar expansion (6 Hyrax tooth-borne ex- Bone-anchored
ex- MD 0.08 (95% CI -1.00
months after completion pander: Mean 5.83 mm pander: Mean 5.75 mm to 1.16)
of expansion phase)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Results
51
Table 1. Fixed versus fixed with mid-palatal expansion (single study comparisons)
(SD 1.54)
(SD 1.98)
(Continued)
P value = 0.88
Molar expansion (12 Hyrax tooth-borne ex- Bone-anchored
ex- MD 0.21 (95% CI -0.77
months after completion pander: Mean 4.24 mm pander: Mean 4.03 mm to 1.19)
of expansion phase)
(SD 1.69)
(SD 1.49)
P value = 0.67
Lamparski 2003
Molar expansion (3 4-point expansion appli- 2-point expansion appli- P value = “No significant
months after completion ance (Hyrax): Not re- ance: Not reported by differences were found”
of expansion phase)
ported by group
group
Canine expansion (3 4-point expansion appli- 2-point expansion appli- P value = 0.331 (as remonths after completion ance (Hyrax): Mean 3. ance: Mean 1.7 mm
ported in the study - no
of expansion phase)
034 mm
SD reported)
Martina 2012
Molar
expan- Slow maxillary expan- Rapid maxillary expan- MD 0.60 (95% CI -0.85
sion (7 months after start sion:
sion:
to 2.05)
of treatment)
Mean 6.3 mm (SD 2.1) Mean 5.7 mm (SD 1.6) P value = 0.42
Mossaz-Joelson 1989
Molar expansion (7-15 Bonded Minne: Mean 7. Banded Minne: Mean 8. P value = NS (as reported
weeks after start of treat- 9 mm (SD 1.5)
3* mm (SD 1.1)
in the study - number of
ment)
participants included in
analysis not reported)
Canine expansion (7-15 Bonded Minne: Mean 6. Banded Minne: Mean 5. P value = NS (as reported
weeks after start of treat- 4 mm (SD 1.1)
3 mm (SD 1.9)
in the study - number of
ment)
participants included in
analysis not reported)
Stability: relapse of molar Bonded Minne: Mean 2. Banded Minne: Mean 2. P value = NS (as reported
expansion (24 weeks after 3 mm (SD 0.8)
5 mm (SD 0.6)
in the study - number of
completion of expansion
participants included in
phase)
analysis not reported)
Stability: relapse of ca- Bonded Minne: Mean 1. Banded Minne: Mean 1. P value = NS (as reported
nine expansion (24 weeks 6 mm (SD 0.5)
2 mm (SD 0.3)
in the study - number of
after completion of exparticipants included in
pansion phase)
analysis not reported)
Ramoglu 2010
Molar expansion
Semi-rapid maxillary ex- Rapid maxillary expan- MD 0.60 (95% CI -0.55
pansion: Mean 5.71 mm sion: Mean 5.11 mm (SD to 1.75)
(SD 1.66)
1.81)
P value = 0.31
Canine expansion
Semi-rapid maxillary ex- Rapid maxillary expan- MD 0.36 (95% CI -0.64
pansion: Mean 5.13 mm sion: Mean 4.77 mm (SD to 1.36)
(SD 1.47)
1.53)
P value = 0.48
CI: confidence interval; MD: mean difference; min: minimum; max: maximum; NS: not significant; RR: risk ratio; SD: standard
deviation.
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
52
* 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 difference, whereas if the mean were 5.3, the P value is < 0.05 (based on assumption of no dropouts).
Table 2. Fixed versus removable (single study comparisons)
Study
Outcome
Group A
Group B
Results
Godoy 2011
Stability of crossbite correc- Quad-helix:
tion (relapse 12 months af- 3/33
ter correction)
Removable
plate:
3/33
Petrén 2008
Crossbite correction
Quad-helix: 15/15
Composite onlays: 2/15
Molar expansion
Quad-helix: Mean 4.6 mm Composite onlays: Mean 0. MD 4.10 (95% CI 3.45 to
(SD 1.19)
5 mm (SD 0.46)
4.75)
P value < 0.00001
Canine expansion
Quad-helix: Mean 2 mm Composite onlays: Mean 0. MD 1.37 (95% CI 0.68 to
(SD 1.18)
63 mm (SD 0.7)
2.06)
P value = 0.0001
Crossbite correction
Removable
plate: 10/15
Molar expansion
Removable
expansion Composite onlays: Mean 0. MD 3.00 (95% CI 2.19 to
plate: Mean 3.5 mm (SD 1. 5 mm (SD 0.46)
3.81)
54)
P value < 0.00001
Canine expansion
Removable
expansion Composite onlays: Mean 0. MD 2.07 (95% CI 1.37 to
plate: Mean 2.7 mm (SD 1. 63 mm (SD 0.7)
2.77)
2)
P value < 0.00001
expansion RR 1 (95% CI 0.43 to 2.
32)
P value = 1
expansion Composite onlays: 2/15
RR 6.20 (95% CI 1.98 to
19.43)
P value = 0.002
RR 5 (95% CI 1.31 to 19.
07)
P value = 0.02
CI: confidence interval; MD: mean difference; NS: not significant; RR: risk ratio; SD: standard deviation
Table 3. Other single study comparisons
Study
Outcome
Group A
Group B
Lippold 2013
Molar
expan- Fixed bonded Hyrax appli- No treatment: Mean 0.8 P value < 0.001 (as resion (12 months after start ance followed by U-bow mm
ported in the study - no
of treatment)
activator: Mean 5.1 mm
SD for mean change from
baseline reported)
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
Results
53
Table 3. Other single study comparisons
(Continued)
Canine
expan- Fixed bonded Hyrax appli- No treatment: Mean 1 mm P value < 0.001 (as resion (12 months after start ance followed by U-bow
ported in the study - no
of treatment)
activator: Mean 3.6 mm
SD for mean change from
baseline reported)
McNally 2005
Molar
Quad-helix
+ Expansion arch + multi- MD -0.55 (95% CI -1.34
expansion (12 weeks after multi-bracket: Mean 4.54 bracket: Mean 5.09 mm to 0.24)
start of treatment)
mm (SD 1.27)
(SD 1.67)
P value = 0.17
Canine
Quad-helix
Expansion arch + multi- MD -0.72 (95% CI -1.52
expansion (12 weeks after + multi-bracket: Mean 1.4 bracket: Mean 2.12 mm to 0.08)
start of treatment)
mm (SD 1.75)
(SD 1.11)
P value = 0.08
Oshagh 2012
Molar and canine expan- Removable with conven- Removable with spring- Results inadequately resion
tional screw
loaded screw
ported
Thilander 1984
Crossbite correction
Grinding or grinding + ex- No treatment:
pansion plate:
6/28
26/33
RR 3.68 (95% CI 1.77 to
7.64)
P value = 0.0005
CI: confidence interval; MD: mean difference; NS: not significant; RR: risk ratio; SD: standard deviation.
APPENDICES
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.
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 extraoral 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
Orthodontic treatment for posterior crossbites (Review)
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54
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.
6. randomly.ab.
7. trial.ab.
8. groups.ab.
9. or/1-8
10. exp animals/ not humans.sh.
11. 9 not 10
Orthodontic treatment for posterior crossbites (Review)
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55
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$)).mp.
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56
11. (“criss-cross elastic$” or “criss cross elastic$”).mp.
12. (occlusal and grind$).mp.
13. Orthodontics/
14. or/7-13
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
WHAT’S NEW
Last assessed as up-to-date: 21 January 2014.
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 have changed
Inclusion criteria changed to only include randomised controlled 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
Orthodontic treatment for posterior crossbites (Review)
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57
HISTORY
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 have not Substantive amendment. A further CCT has been
changed
found on two-point versus four-point expansion
(Schneiderman 1990) and follow-up data on the treatment group from Lindner 1989 (Tsarapatsani 1999).
Conclusions remain largely unchanged
CONTRIBUTIONS OF AUTHORS
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 SilvestriniBiavati (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.
DECLARATIONS OF INTEREST
Paola Agostino, Alessio Signori, Armando Silvestrini-Biavati, Alessandro Ugolini, Jayne E Harrison, Philip Riley: no interests to declare.
SOURCES OF SUPPORT
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.
Orthodontic treatment for posterior crossbites (Review)
Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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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.
DIFFERENCES BETWEEN PROTOCOL AND REVIEW
• 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.
INDEX TERMS
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]
MeSH check words
Adolescent; Child; Child, Preschool; Humans
Orthodontic treatment for posterior crossbites (Review)
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