Orthodontic treatment for posterior crossbites.
BACKGROUND
'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. It is unclear what causes posterior crossbites and they may develop or improve at any time from when the baby teeth come into the mouth to when the adult teeth come through. Several treatments have been recommended to correct this problem. Some treatments widen the upper teeth whilst 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.


OBJECTIVE
The aim of this review was to evaluate orthodontic treatments used to expand the maxillary dentition and correct posterior crossbites.


METHODS
All randomised and controlled clinical trials identified from the Cochrane Controlled Trials Register according to the Oral Health Group Search Strategy and stored in the Cochrane Collaboration Oral Health Group Database of Clinical Trials, a MEDLINE search using the Mesh term Palatal Expansion Technique and relevant free text words, hand searching the British, European and American journals of orthodontics and Angle Orthodontist, and the bibliographies of papers and review articles which reported the outcome of orthodontic treatment to expand the maxillary dentition and/or correct a posterior crossbite that were published as abstracts or papers between 1970 and 1999.


METHODS
All randomised and controlled clinical trials published as full papers or abstracts which reported quantitative data on the outcomes crossbite correction, molar and/or canine expansion, signs and symptoms of temporomandibular joint dysfunction or respiratory disease.


METHODS
Data were extracted without blinding to the authors, treatments used or results obtained. The first named authors of randomised and controlled clinical trials were written to in an attempt to establish the method of randomisation / allocation and identify unpublished studies. Odds ratio, relative risk, relative risk reduction, absolute risk reduction, the number need to treat and corresponding 95% confidence intervals, were calculated for event data. The weighted mean difference and 95% confidence intervals were calculated for continuous data.


RESULTS
Using the search strategy seven randomised and five controlled clinical trials were identified but following correspondence with the authors, three of the randomised and one of the controlled clinical trials were reclassified giving five randomised and seven controlled clinical trials for inclusion in the review. For the update an additional CCT was found giving five RCTs and eight CCTs for inclusion in this update. Trials comparing occlusal grinding in the primary dentition with/without an upper removable expansion appliance in the mixed dentition versus no treatment, banded versus bonded and two point versus four point rapid maxillary expansion, banded versus bonded slow maxillary expansion, transpalatal arch with/without buccal root torque, an upper removable expansion appliance versus quad-helix were identified. Occlusal grinding in the primary dentition with/without the addition of an upper removable expansion plate, in the mixed dentition for those children who did not respond to grinding, was shown to be effective in preventing a posterior crossbite in the primary dentition from being perpetuated to the mixed and permanent dentitions. No evidence of a difference in treatment effect (molar and canine expansion) between the test and control intervention was found in the trials which compared banded versus bonded and two point versus four point rapid maxillary expansion, banded versus bonded slow maxillary expansion, transpalatal arch with/without buccal root torque, or upper removable expansion appliance versus quad-helix. Insufficient data were provided in the paper comparing two point versus four point rapid maxillary expansion to allow a formal analysis.


CONCLUSIONS
The evidence from the trials reported by Lindner (1989); Thilander (1984) suggests that removal of premature contacts of the baby teeth is effective in preventing a posterior crossbite from being perpetuated to the mixed dentition and adult teeth. When grinding alone is not effective, using an upper removable expansion plate to expand the top teeth will decrease the risk of a posterior crossbite from being perpetuated to the permanent dentition. The comparisons of treatments made in the trials reported by Asanza (1997); Sandikçioglu (1997); Mossaz-Joëlson (1989); Ingervall (1995); Schneidman (1990) were inconclusive so recommendations for clinical practice can not be made based on the results of these trials. (ABSTRACT TRUNCATED)
Harrison
J E
JE
Department of Clinical Dental Sciences, Liverpool University Dental Hospital, Pembroke Place, Liverpool, Merseyside, UK, L3 5PS. Jayne.Harrison@rlbuh-tr.nwest.nhs.uk
Ashby
D
D
D000328:Adult; D006801:Humans; D008310:Malocclusion / Q000628:therapy*; D018704:Orthodontic Retainers; D009971:Orthodontics, Corrective / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000628:therapy