Temporomandibular joint symptoms and dysfunction of surgically operated cases of facial deformity. The first report. Multivariate analysis.

Skeletal malocclusion and orthognathic surgery may significantly influence the morphology and function of the temporomandibular joint and the position or direction of the mandibular condyle, thereby altering temporomandibular joint symptoms and signs or jaw function.Forty patients (15 males and 25 females, aged 18-36 years and followed for 18-46 months) with facial deformities and major malocclusions were studied. The subjects included 37 cases of mandibular prognathia, 10 cases of facial asymmetry and 7 cases of open bite. All cases underwent sagittal splitting osteotomy. Each patient was reviewed to elucidate the factors involved in temporomandibular joint symptoms and mandibular dysfunction by Type I and Type 11 quantitative theory.All signs and symptons of temporomandibular joint and mandibular dysfunction were recorded just before orthognathic surgery and at more than 18 months after surgery.Analyses were performed using the external criterion of ‘TMJ score’ for Type I quantification and three categories of external criteria (i. e., ‘no symptoms’, ‘mainly TMJ symptoms’.‘mainly muscle symptoms’) for Type II quantification. The explanatory variables were ‘surgical method’, ‘bone fixation’, ‘operator’, ‘increase of overjet’, ‘increase of overbite’, ‘increase of difference between upper and lower jaw midlines’, ‘presurgical mandibular deviation of jaw opening’, ‘presurgical TMJ sound’, ‘presurgical TMJ pain’ and ‘presurgical muscular pain’.The results were as follows:1. Type I quantitative theory analysis revealed that postsurgical TMJ scores were most closely related to the factor of ‘operator’, and strongly related to increase of difference between upper and lower jaw midlines.2. Type 11 quantitative theory analysis showed that the main symptoms of the cases were affected dominantly by the factor of ‘operator’, followed by the factors of ‘presurgical muscle pain’ and ‘increase of difference between upper and lower midlines’.3. Strong correlation of the ‘operator’ and ‘increase of difference between upper and lower midlines’ with temporomandibular joint symptoms and dysfunction suggests that technical factors of the surgical procedure and facial asymmetry significantly affect the quantity and quality of temporomandibular joint symptoms.