Traditional orthodontic treatment, orthodontic appliances, and extraction for orthodontic treatment do not appear to cause TMD

Studies

A total of 960 articles were initially identified by a systematic search using MEDLINE, references from review articles, and a list from Dr Rolf Behrents. Thirty-one studies, all in English, met the following inclusion criteria: (1) The patients studied had completed orthodontic treatment—although studies including subjects who received orthodontic or orthognathic therapy to treat TMD were excluded. (2) Each patient had received a clinical TMD evaluation; imaging evaluations were excluded. (3) Studies could have retrospective or prospective designs; case reports (<10 subjects) and opinion papers were excluded. If several articles were published on the same study, 1 representative article was chosen for inclusion in this meta-analysis.

Of these 31 articles, 18 were cross-sectional studies or surveys, and 13 were longitudinal studies.

Suspected Etiology

Orthondontic therapy and extraction for orthodontic therapy.

Main Outcome Measure

Outcome measures varied greatly. Some studies measured specific signs and/or symptoms of TMD (eg, TMJ sounds, tenderness) whereas others used indices for TMD evaluation (eg, Helkimo Index, Craniomandibular Index).

Main Results

Because of the heterogeneity of the studies, the authors were not able to perform a true meta-analysis, in which the results from multiple studies are pooled to give an overall estimate of the risk. However, the authors reported that no orthodontic therapies were associated with an increased prevalence of TMD, other than mild signs. Additionally, only 1 study reported that orthodontic extractions were associated with an increased prevalence of TMD. Table III provides a summary of the outcomes for the 31 studies.