Long-term effects of chin-cap therapy on the temporomandibular joints.

It is commonly believed that upward/backward forces applied to the condyle by a chin-cap cause temporomandibular dysfunction (TMD). In the current study the long-term follow-up (2-11 years) of patients treated with a chin-cap was investigated regarding signs and symptoms of TMD. The treatment group consisted of 32 individuals who had a skeletal Class III malocclusion treated using chin-cap therapy (mean age 18.4 years). The two control groups contained 39 untreated subjects with skeletal Class III malocclusions (mean age 15.5 years) and 53 dental students (mean age 19.2 years) with acceptable normal occlusions. Functional examination of the subjects was carried out and those with at least one sign/symptom (clicking, pain, or deviation) were identified as the 'symptomatic' subgroup. The distribution of symptomatic individuals was 25 per cent in the treatment group, 23 per cent in the Class III malocclusion group, and 41.5 per cent in the normal group (dental students). In addition, the frequency of signs and symptoms of TMD in the symptomatic individuals was also investigated. There were no signs of crepitus in any subject, clicking was found in 50 per cent of the treatment group and pain in 54.5 per cent of the normal group. The results of this long-term follow-up indicate that chin-cap treatment is neither a risk factor nor a prevention for TMD. Age and stress factors should always be considered in the evaluation of TMD.