Orthodontic treatment and temporomandibular disorders: is there a relationship? Part 1: Clinical studies

The relationship between orthodontic treatment and temporomandibular disorders (TMD) has long been of interest to the practicing orthodontist, but only during the last decade or so have a significant number of methodologically-sound clinical studies been conducted that have investigated this association. The aim of this paper is to critically review particularly those studies that have been published since 1989 and to answer the following questions: 1. Does orthodontic treatment with fixed or removable appliances lead to a greater incidence of TMD? 2. Does the extraction of premolars as part of an orthodontic treatment plan result in a greater incidence of TMD? 3. Does orthodontic treatment prevent or cure TMD? For this purpose, we conducted a MEDLINE search, complemented by a hand search in selected journals. We found 21 publications of studies related to the orthodontic-TMD interface. Based on these studies, the following statements can be made: 1. Orthodontic treatment performed during adolescence does not increase or decrease the chances of developing TMD later in life. There is no evidence of an elevated risk for TMD associated with any particular type of orthodontic mechanics. 2. The extraction of teeth as part of an orthodontic treatment plan does not increase the risk of TMD. 3. Thus far, there is no compelling evidence that orthodontic treatment prevents TMD, although the role of unilateral posterior crossbite correction in children may warrant further investigation. Likewise, there is no convincing evidence that TMD can be cured by orthodontic treatment.