Orthodontic treatment in relation to symptoms attributed to dysfunction of the temporomandibular joint. A 10-year report of the University of Groningen study.

This article reports a 10-year longitudinal investigation of symptoms attributed to temporomandibular joint dysfunction in orthodontically treated subjects. The study was designed to test the prevailing assumption that orthodontic therapy is an etiologic factor in inducing TMJ dysfunction. Although the study was prospective in design, several unexpected methodologic complications limited the data analyses. Presumed joint dysfunction symptoms were assessed in orthodontically treated subjects. The presumed symptoms were subsumed under three categories: subjective symptoms, objective symptoms, and x-ray findings. The prevalence of symptoms was analyzed before treatment, 4 years later subsequent to retention, and 10 years after the initiation of the study. Comparisons of symptom frequencies were made between Begg and activator-treated subjects. The results of this investigation led to the following conclusions. In studying temporomandibular joint dysfunction, subjective symptoms, objective symptoms, and x-ray findings should be analyzed separately. Registration of symptoms during orthodontic treatment should probably be attributed to age changes rather than to treatment procedures. Begg Class I and Class II treatments do not reduce the percentages of symptoms registered. Begg Class I and Class II treatments do not affect the incidence of subjective symptoms. Begg Class I and Class II treatments do not affect the incidence of x-ray findings. Begg Class I and Class II treatments create higher percentages of objective symptoms after retention, but not in the long run (10 years). Ten years after the beginning of treatment, the initial differences in symptomatology between activator and Begg children no longer exist.