S4B-16 SESSION 4B: ORTHOGNATHIC / TREACHER-COLLINS MANDIBULAR OUTER CORTEX SPLITTING OSTEOTOMY: IS IT AN EFFECTIVE FACIAL CONTOUR SURGERY?

Abstract

Introduction: Background: Mandibular outer cortex splitting osteotomy(MOCSO) is widely used as a facial contour surgery to shape a narrower lower face. Mandible outer cortex regeneration occur as a natural process of bone healing. The volume of mandible regeneration largely affect the clinical result of MOCSO. However, the postoperative mandible regeneration were rarely investigated. This study aim to clarify the morphologic change of mandible after MOCSO. Methods: A retrospective study of MOCSO from 2009–2016 was conducted. 16 patients with preoperative, immediately postoperative and 12 months postoperative CT were enrolled. 3D visual reconstruction and registration of preoperative, immediately postoperative and postoperative mandible were performed. MOCSO area was segmented based on the immediately postoperative mandible bone defect. Then 3D comparison and analysis of the MOCSO area was performed. Results: The bone volume of the MOCSO area was 6921.5±878.1m3 preoperative; 4181.7±574.1m3 immediately postoperative; 6674.7±919.7m3 6 months postoperatively. The bone regeneration rate of the MOCSO area is 95.17% 12 months postoperatively. Conclusion: The bone regeneration rate of MOCSO is over 90%. Although our result needs to be further strengthened by clinical study with more cases, practitioners should be cautious about adopting MOCSO as a valid facial contour surgery.