Long-term development after treatment of mandibular dysfunction and osteoarthrosis. A clinical-radiographic follow-up and an animal experimental study.

The purpose of this thesis was to investigate the long-term development of signs and symptoms in patients with temporomandibular joint (TMJ) pain/dysfunction after treatment, to analyse factors of importance for the long-term prognosis, to evaluate TMJ radiography in these disorders and to develop a model for experimental joint lesions where also the effects of intra-articular injections of corticosteroid and hyaluronic acid in such joint lesions were studied. Signs and symptoms of dysfunction in the patients treated for TMJ pain/dysfunction were few at the follow-up and significantly reduced compared with the findings at the start of treatment. Less than one fifth of the patients had had recurrent symptoms of some significance. Poor general health was found to have a negative influence on the prognosis. Few correlations were found between occlusal factors and dysfunction. In patients with extremely long periods of treatment psychosocial factors were evident. The long-term prognosis of TMJ osteoarthrosis was as good as for neuromuscular problems but crepitation often persisted at the follow-up. Radiographic abnormalities of structure and shape of the TMJ generally of a small extent were frequent in patients with TMJ pain/dysfunction both in those examined during the treatment period and in those only radiographed at the follow-up. Findings were frequent also in patients treated for mainly mandibular (neuromuscular) dysfunction. At the follow-up a slight increase in number and extent of abnormalities were found. Signs and symptoms of dysfunction showed poor correlation with the radiographic findings. Decreased number of occluding pair of teeth, as well as crepitation, was however positively correlated to abnormalities of structure and shape. The intra-articular injection of papain in guinea-pig knee-joints constantly resulted in development of joint lesions with individual variations. Treatment of such joint lesions with corticosteroid and hyaluronic acid had little influence on the overall lesions, but the results indicate that hyaluronic acid inhibit granulation tissue formation and development of deviation in shape of the joint components.