Long-term stability after orthodontic treatment remains inconclusive

PubMed and Cochrane Library electronic databases were searched from 1966 to January 2005. Reference lists of the relevant studies were searched by hand.

For inclusion, articles had to satisfy the following criteria: have a follow-up period of at least 5 years post-retention; report on randomised clinical trials (RCT), prospective or retrospective clinical controlled studies or on cohort studies; and investigate orthodontic treatment including fixed or removable appliances, selective grinding or extractions.

Screening of eligible studies, data extraction and assessment of methodological quality was conducted independently and in duplicate. The level of evidence of the included studies was graded as high, moderate or low according to predetermined criteria.

The search strategy resulted in 1004 abstracts or full-text articles, of which 38 met the inclusion criteria. Treatment of crowding resulted in successful dental alignment but the mandibular arch length and intercanine width gradually decreased, and crowding of the lower anterior teeth reoccurred post-retention. This condition was unpredictable at the individual level. Treatment of Angle class-II division-1 malocclusion with a Herbst appliance normalised the occlusion. Relapse occurred but could not be predicted at the individual level. The scientific evidence was insufficient to draw conclusions about treatment of cross-bite, angle class III, open-bite and various other malocclusions, or about long-term patient satisfaction.

Despite a large number of studies on long-term stability after orthodontic treatment, this systematic review shows that evidence-based conclusions are few. This is mostly because of inherent problems with retrospective and inferior study design. There is a great need for well-designed prospective studies with untreated control groups; sufficient sample sizes; and sample selection according to type of malocclusion, age and growth pattern.