Functional disturbances of the masticatory system related to temporomandibular joint involvement by rheumatoid arthritis.

Several theories have been proposed concerning the aetiology of dysfunction of the temporomandibular joint (TMJ). To analyse the relationship of radiographic changes to clinical signs and symptoms of TMJ dysfunction, the present study was conducted in subjects highly predisposed to TMJ involvement, i.e. in patients with rheumatoid arthritis (RA). The aim of the study was to estimate the frequency of disturbances in the masticatory system of RA patients. In addition, the relationship between TMJ abnormalities and the signs and symptoms of dysfunction was investigated. The study consisted of sixty patients with RA and forty control subjects. Asymptomatic subjects were more frequent in the RA group than in the controls. Muscle pain during palpation was recorded in 53.3%, clicking in 53.3%, crepitation in 21.7%, reduced movement capacity of the TMJ in 41.7%, and restricted mouth opening in 31.7% of the RA patients examined. In the control group the most common symptoms and signs were clicking (57.5%), muscle pain during palpation (57.5%) and restricted opening (25.0%). Normal radiographic appearance of the TMJ in RA patients was found in 31.7%. Minor changes comprised 31.7%, moderate changes 21.6%, and severe changes or total loss of the condyle 15.0%. In the control group a normal joint was detected in 87.5%, while minor changes were encountered in 7.5%, and moderate or severe changes only in 5.0%. No relationship was found between Helkimo's anamnestic, clinical or occlusal indices and the severity of the disease graded according the criteria outlined by the American Rheumatism association (ARA). In the ARA group the frequency of signs and symptoms of dysfunction increased with the destructive changes in the TMJ area. In the controls, muscle pain during palpation and clicking sounds in the TMJ were most commonly connected with normal radiographic appearance of the TMJ. In the discriminant analysis the most discriminating factors were crepitation, tenderness to palpation of muscles and movement of TMJ.