Maxillary expansion is a common orthodontic treatment used for the correction of posterior crossbite resulting from reduced maxillary width.  The aim of this review recent was to  assess the effectiveness of various modalities of orthopaedic/orthodontic expansion of maxillary arches with crossbite and the associated 6 month post retention stability.

The authors searched ,Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, LILACS, and the WEB of SCIENCE  for randomised controlled trials for the correction of posterior crosbite.

Twelve articles were included, most had methodological problems, small sample size,  possible bias and unaccounted for confounding variables, lack of blinding in measurements, and deficient statistical methods. Treatment outcomes were different depending on the appliance used, tooth tissue-borne/tooth-borne expanders, bonded semi-rapid maxillary expansion (SRME), or rapid maxillary expansion (RME); in any case, methodological flaws prevent any sound conclusions.

Stable results have been measured at the 6 month follow-up after removal of the retention plate in the treated groups in the maxillary intermolar and intercanine distances. Long-term stability results should be assessed.

The authors suggest that future research should follow the Consolidated Standards of Reporting Trials (CONSORT) Statement for the reporting of RCTs.  They also indicated that while many treatments appear to be successful in the short-term there is little information on long-term outcomes.

Zuccati G, Casci S, Doldo T, Clauser C. Expansion of maxillary arches with crossbite: a systematic review of RCTs in the last 12 years. Eur J Orthod. 2011 Dec 9. [Epub ahead of print] PubMed PMID: 22158610.

Comment

The findings are broadly similar to those in the Cochrane review by Harrison and Ashby (2001)  and it is perhaps disappointing the despite the availability of more RCTs in the intervening period  we do not appear to have moved much further forward in determining the most effective approach to the treatment of posterior crossbites.

Harrison JE, Ashby D. Orthodontic treatment for posterior crossbites. Cochrane Database of Systematic Reviews 2001, Issue 1. Art. No.: CD000979. DOI: 10.1002/14651858.CD000979.