Analysis of short face tendency and it's determinant factors after bilateral sagittal split ramus osteotomy of mandibular prognathism

ABSTRACT

PURPOSE: The purpose of this study was to analyse the facial changes and factors contributing to then after bilateral sagittal split ramus osteotomy of mandibular prognathism. MATERIALS AND METHODS: Forty patients with Class III dental and skeletal malocclusion who were treated with bilateral sagittal split ramus osteotomy were reviewed. Frontal and lateral cephalometric radiographs were taken preoperatively, immediate postoperatively and more than six months postoperatively in each patient. After tracing the cephalometric radiographs, various parameters were measured. RESULTS: 1. Gonial angle at postoperative two days was decreased about 10.4 degrees than preoperatively and gonial angle at postoperative six months was increased about 6.8 degrees than postoperative two days. So, gonial angle at postoperative six months was decreased about 3.6 degrees than preoperative gonial angle. 2. Facial height postoperative two days was decreased about 0.8mm than preoperatively and facial height at postoperative six months was decreased about 0.7mm than postoperative two days. So, facial height at postoperative six months was decreased about 1.5mm than preoperative facial height. 3. Mandibular width postoperative two days was decreased about 1.0mm than preoperatively and mandibular width at postoperative six months was increased about 1.8mm than postoperative two days. So, mandibular width at postoperative six months was decreased about 2.8mm than preoperative mandibular width. 4. Amount of set back and mandibular plane angle were not influencing on relapse degree. CONCULSION It is thought that bilateral sagittal split ramus osteotomy in mandibular prognathic patients is effective to improve long face and steep gonial angle. More prudent operation and careful postoperative management is required to maintain stable face postoperatively. Further research for soft tissue changes and factors which are related with relapse is needed.