A COMPUTER ANALYSIS ON THE CONDYLAR PATH OF BALANCING SIDE IN MANDIBULAR LATERAL MOVEMENT

하악 측방운동시 평형측 과두의 운동 궤적에 관한 컴퓨터 분석

The purpose of this study was to research the condylar path and the anterior angle of glenoid fossae and classify the patterns of condylar path. Thirty male and female dental students with normal occlesion and masticatory system ranging in age from 21 to 30, without present symptoms and an)r history of TM joint disturbance, were selected for this study. Transcranial radiographs of TM joints under mandibular lateral movement were obtained. By the computer analysis on the radiographs, the angle of posterior slope of articular eminance, the sagittal condylar guidance angie, condylar movement patterns and the height of glenoid fossa was measured respectively, and studied their interrelationship comparatively. The results obtained were as follows : 1. The total distance of condylar movement on balancing side during mandibular lateral movement was 4.55mm for Lt. and 4.78mm for Rt. when mandible moved from C.R. to canine to canine relation and 7.86mm for the Lt. and 8.10mm for the Rt. when mandible moved from C.R. to 7.5mm. 2. The horizontal distance of condylar movement on balancing side during mandibular lateral movements was 3.16mm for the Lt. and 3.52mm for the Rt. when mandible moved from C.R. to canine to canine relation and 6.10mm for the Lt. and 6.30mm for the Rt. when mandible moved from C.R. to 7.5mm. 3. The sagittal condylar guidance angle on balancing side during mandibular lateral movements was $45.96^{\circ}$ for the Lt. and $43.22^{\circ}$ for the Rt. when mandible moved from C.R. from canine to canine relation and $41.14^{\circ}$ for the Lt. and $39.77^{\circ}$ for the Rt. when mandible moved from C.R. to 7.5mm. 4. The height of glenoid fossa was 8.23mm for the Lt. and 7.80mm for the Rt. and the angle of posterior slope of articular eminence was $38.30^{\circ}$ for the Lt. and $38.79^{\circ}$ for the Rt. by method-A and $55.61^{\circ}$ for the Lt. and $55.64^{\circ}$ for the Rt. by method-B. 5. The sequence of the frequency of condylar movement patterns on balancing side during mandibular lateral movement were concave type(30 cases), convex type(16 cases), reverse S shape curve(9 cases) and S shape curve(5 cases) when mandible moved from C.R. to canine to canine relation and concave type(27 cases), 5 shape curve(13 cases), convex type(11 cases) and reverse S shape curve(9 cases) when mandible moved from C.R. to 7.5mm.