Micrognathia, temporomandibular joint changes and dental occlusion in juvenile rheumatoid arthritis of adolescents and adults.

Clinical and radiographic examinations of the jaw skeleton of 20 patients aged 15-35 with juvenile rheumatoid arthritis (JRA) and a varying degree of micrognathia were made. Symmetrically underdeveloped mandible and unaffected maxilla were generally found by means of radiographic cephalometry. Overjet (5-15 mm) occurred in 10 patients, incisal protrusion in eight and distal molar relation in 16 (bilaterally in 10). Temporomandibular joint (TMJ) symptoms, mainly pain and morning stiffness, were reported from case histories in 13 patients. Symptoms and signs at the examination were few, except crepitus found in 11 patients, and restricted mouth opening observed in all the patients. In four patients no symptoms had ever been noted. Severe radiographic changes were a characteristic feature in all the patients. Mandibular size (gn-ar distance) was significantly smaller in patients with complete destruction of the mandibular head than in those with partial destruction, indicating a causal relationship between mandibular underdevelopment and arthritis of the TMJ. Flat fossa, anteroposition of remnants of the mandibular head and reduced condylar movement at maximum opening of the mouth were found. Etiologic factors of micrognathia in JRA are discussed, as well as demand and need for treatment.