下顎骨後退手術後 下顎運動의 變化에 關한 硏究

Sirognathographic patterns of mandibular motion after mandibular setback surgery

To observe the effect of mandibular setback surgery on the mandibular various movement and functional rchabilitation, sirognathographic registration (Bio-Pack. Bioresearch Inc. Wisconsin, U.S.A). was obtained before and at IMF removal, 6, 12 months after mandibular setback surgery periodically in the 32-mandibualr prognathism patients. To group the corelation of orthognathic surgery and mandibular movements, statistical analysis was performed by the operation methods (sagittal split ramus osteotomy and vartical ramus osteotomy) and the duration of IMF. The results were as follows. 1. There showed no differnce in the mandibular open-closing patterns between normal and mandibular prognathism patient and it did not affected by mandibular seback surgery longtermly. 2. After mandibular setback surgery, the mandibular open-closing veiocity patterns were significantly improved that, there was decrease in irregularity(from 37% to 15%), reduction of premature contact, and increase in maximal velocity(from 251.6mm/sec to 295.7mm/sec). 3. After mandibular setback surgery, the amout of maximal protrusion and protrusive angle increased 12 months after surgery and there showed better recovery rate in the sagittal split ramus osteotomy than in the vertical ramus osteotomy group. 4. The amount of hinge and translatory movement after mandibular setback surgery showed slow recovery and did not affected by surgery. 5. The amount and angle of lateral movement after mandibular setback surgery were decreased immediately after IMF removal but recovered soon and increased to the range of preoperative value and these had no relationship with the operation methods and the duration of intermaxillary fixation(IMF). 6. The maximal mouth opening after mandibular setback surgery was decreased immediately but recovered at 12 months after surgery. This general tendency can be interpreted that mandibular setback surgery had no harmful influence upon the mandibular motion and in some parts, clinical improvement was achieved with positive consequance in the function of the muscle and temporomandibular joint.