[Chronic trismus in the severe skeletal Class III cases].

In general, patients who have trismus as chief complaint often have acute symptoms, but limited number of these patients have chronic trismus. We studied 51 patients (mean age; 18y 4n) with severe skeletal class III (less than ANB less than or equal to O), who need surgical treatment. Three types were classified according to the movement of the mandibular head at the maximum mouth opening at their first visit. A-type; the mandibular head hardly move. B-type; it dose not move beyond articular eminence. C-type; it moves beyond articular eminence. These classifications were applied to the both sides of the mandibular head in the 51 patients to divide into 5 types (Type AA, Type AB, Type BB, Type BC, Type CC). Those patients were analyzed according to these five types. The results obtained were as follows; 1) Seventy-three percent of all the cases were female in this study. Sixty-five percent of both the sexes had chronic trismus without having subjective symptoms on the mandibular joints in their daily lives. Type AA, AB, BB, and BC accounted for 12%, 6%, 31%, and 16% respectively. 2) There were fewer contacts in the upper posterior antagonist teeth in AA and AB; particularly at 5. In all the cases of Type CC, contacts with the antagonist tooth 5 were seen. 3) As a conclusion, movement of the mandibular head in the patients with trismus are found to have a characteristic limitation at the maximum mouth opening and the stress points in the occlusal contacts at the centric occlusion to be the posterior area.