A 20-year follow-up of signs and symptoms of temporomandibular disorders and malocclusions in subjects with and without orthodontic treatment in childhood.

This investigation analyzes the influence of orthodontic treatment on signs and symptoms of temporomandibular disorders (TMDs) and different malocclusions during a 20-year period. Originally, 402 randomly selected 7-, 11-, and 15-year-old subjects were examined clinically and by means of a questionnaire for signs and symptoms of TMDs. The examination was repeated after five and ten years. After 20 years, 320 subjects (85% of the traced subjects) completed the questionnaire. The oldest age group,now 35 years of age, was invited to a clinical examination, and 100 subjects (81% of the traced subjects) were examined. The correlations between signs and symptoms of TMD and different malocclusions were mainly weak, although sometimes statistically significant. Lateral forced bite and unilateral crossbite were correlated with TMD signs and symptoms at the 10- and 20-year follow-ups (r = 0.38, P < .05 and r = 0.34, P < .01, respectively). Subjects with malocclusion over a long period of time tended to report more symptoms of TMD and to show a higher dysfunction index, compared with subjects with no malocclusion at all. There were no statistically significant differences in the prevalence of TMD signs and symptoms between subjects with or without previous experience of orthodontic treatment. This 20-year follow-up supports the opinion that no single occlusal factor is of major importance for the development of TMD, but a lateral forced bite between retruded contact position (RCP) and intercuspal position (ICP), as well as unilateral crossbite, may be a potential risk factor in this respect. Furthermore, subjects with a history of orthodontic treatment do not run a higher risk of developing TMD later in life, compared with subjects with no such experience.