A systematic review concerning early orthodontic treatment of unilateral posterior crossbite.

The aim of this study was to assess the orthodontic treatment effects on unilateral posterior crossbite in the primary and early mixed dentition by systematically reviewing the literature. A literature search was performed by applying the Medline database (Entrez PubMed) and covering the period from January 1966 to October 2002. The inclusion criteria were primary and early mixed dentition with unilateral posterior crossbite, randomized controlled trials (RCT), prospective and retrospective studies with concurrent untreated as well as normal controls, and clinical trials comparing at least two treatment strategies without any untreated or normal group involved. Two reviewers extracted the data independently and also assessed the quality of the studies. The search strategy resulted in 1001 articles, and 12 met the inclusion criteria. Two RCTs of early treatment of crossbite have been performed, and these two studies support grinding as treatment in the primary dentition. There is no scientific evidence available to show which of the treatment modalities, grinding, Quad-helix, expansion plates, or rapid maxillary expansion, is the most effective. Most of the studies have serious problems of lack of power because of small sample size, bias and confounding variables, lack of method error analysis, blinding in measurements, and deficient or lack of statistical methods. To obtain reliable scientific evidence, better-controlled RCTs with sufficient sample sizes are needed to determine which treatment is the most effective for early correction of unilateral posterior crossbite. Future studies should also include assessments of long-term stability as well as analysis of costs and side effects of the interventions.