Post Operative Evaluation of Sagittal Split Osteotomy of the Ascending Ramus and Screw Fixation by the Repositioning Technique for External Bone Fragment

Abstract

Forty-One cases of mandibular protrusion undergoing sagittal-split osteotomy of the ascending ramus and screw fixation by the repositioning technique for external bone fragments of Matsuura et al. were studied in regard to the periodical pcstoperative changes in lateral and frontal cephalometric roentgenograms. Concurrently, factors involved in relapse were analyzed. The following results were obtained: 1. Cephalometric variables measured postoperatively were contrasted with the corresponding values obtained 2 months, 6 months and 1 year postoperatively. Significant differences were not noted in any of the variables studied.
2. Significant differences were noted between the preoperative and postoperative form of the gonial angle. This study demonstrated postoperative improvement in the form of the gonial angle.
3. The degree of posterior displacement of the mandible did not bear a significant relationship with relapse.
4. Bilateral differences in posterior displacement was not significantly related to relapse.
5. Preoperative anterior tooth overlap was not significantly related to relapse.
6. Analysis of postoperative changes between 1 year and 3 years, studied in 10 cases, did not reveal any significant differences.
7. External bone fragments moved medially postoperatively, resulting in bilateral asymmetry. Although extraoral movement was evident after 1 year compared with just after surgery, bilateral asymmetry persisted.
8. Factors involved in relapse underwent multiple regression and principal component analysis, but the relation between preoperative skeletal characteristics and relapse was minimal.