Long-term effects of orthodontic treatment, including extraction, on signs and symptoms attributed to CMD.

The prevalence of signs and symptoms attributed to craniomandibular disorders (CMD) was established in an orthodontically treated sample. The effect of orthodontic therapy upon this prevalence was studied by monitoring three groups of patients whose treatment procedures were different. The first group was treated with functional appliances, the second with Begg light wire, and the third with chin cups. In addition, the effect of extraction upon the prevalence was studied by monitoring three groups in which different extraction decisions had been made: four first premolars extracted, all other types of extraction, and no extraction. Based upon the finding of similar prevalences after 20 years of observation, it appears that neither orthodontic treatment nor extraction has a causal relationship with the signs and symptoms of CMD recorded during this study.