The purpose of this sutudy was twofold ; the first purpose is to ascertain the direction of condylar displacement and changes of joint space in patient receiving mandibular ramus osteotomy for the mandibular prognathism. The second purpose is to
determine whether a significant relation exists between joint space changes and postoperative skeletal changes. The material of this study was composed of 16 patients who were operated for mandibular prognathism by sagittal split osteotomy(n=8)
and
vertical ramal osteotomy(n=8). Each patient had a radiographic taken. Cephalometric radiographs were performed preoperatively, immediate postoperatively, and at least 6 months after surgery. TMJ tomograms were taken within 1 week preoperative and
6-24months later after the surgery.
@ES The results were as follows ;
@EN 1. On lateral cephalogram, there were significant decreases in posterior facial height, SNB angle, SNPo angle, and correction of anterior crossbite, as the mandible was surgically retruded.
2. The mandibular condyles had tendencies for displacement to anterosuperior direction in SSRO group and to anteroinferior direction in VRO group.
3. On TMJ tomogam, although there were tendencies for decreases anterior, posterior joint space, and increases posterior joint space in SSRO group, there were not statistically significant(p>0.05). In VRO group, although there were tendencies
for
increases anterior, superior, and posterior joint space, there also were not significant(p>0.05).
4. There were existed some correlation between joint space change due to condylar displacement and skeletal relapse. It seemed that postoperative skeletal relapse was influenced by condylar displacement after mandibular setback by ramal
osteotomy.
5. The bony changes after mandibular ramus osteotomy for mandibular prognathism were noted as double contour on the posterior part of the condylar head, and flattening on the anterosuperior part of the condylar head.
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