Postoperative Stability After Sagittal Split Ramus Osteotomies for a Mandibular Setback With Monocortical Plate Fixation or Bicortical Screw Fixation
This work was presented at the 2006 American Association of Oral and Maxillofacial Surgeons (AAOMS) 88th Annual Meeting Scientific Poster Session (Poster No. 16) on October 5, 2006.
Purpose
This comparative study was performed to analyze mandibular stability after bilateral sagittal split ramus osteotomies for a mandibular setback with a monocortical plate fixation or bicortical screw fixation.
Patients and Methods
A total of 60 patients with a skeletal Class III malocclusion who underwent sagittal split osteotomies and mandibular setback were included in the present study. Among the patients, 30 were osteosynthesized monocortically with a titanium plate, while the other 30 were osteosynthesized bicortically with positioning screws. This retrospective study used cephalometric radiographs taken preoperatively (T0), and at 1 week (T1), 3 months (T2), and 1 year (T3) postoperatively. The linear and angular changes of the cephalometric landmarks of the chin region were measured at each time period, and the changes of each cephalometric landmark were determined for 4 different time intervals: T0 to T1 (ΔT1), T1 to T2 (ΔT2), T2 to T3 (ΔT3), and T0 to T3 (ΔT4). Postoperative changes in mandibular shape were analyzed using a paired t test to determine the stability of fixation methods.
Results
The surgical changes (ΔT1) could be characterized as posterior movements of the mandibular body and posterosuperior movements of the chin landmark. The results of the cephalometirc analysis at 3 and 12 months postsurgery (ΔT2 and ΔT3) could be characterized as anterosuperior movements of the mandible. In both treatment groups, surgical changes were relatively well maintained. Likewise, analysis of the horizontal and vertical movements of the chin landmarks indicated a similar tendency in both groups. There were no statistically significant differences between the measurements of postoperative changes at each time period after surgery.
Conclusions
The findings of our study suggest that there were no significant differences in postoperative changes in mandibular shape in both the monocortical and bicortical fixation groups after sagittal split ramus osteotomy. We concluded that monocortical osteosynthesis using a miniplate could be used to obtain stable postoperative changes after mandibular setback.
⁎Assistant Professor, Department of Dentistry/Oral and Maxillofacial Surgery, Seoul National University Boramae Hospital, Seoul, Korea.
†Resident, Department of Dentistry/Oral and Maxillofacial Surgery, Seoul National University Boramae Hospital, Seoul, Korea.
‡Clinical Instructor, Department of Orthodontics, Seoul National University Dental Hospital, Seoul; Private Practice in Orthodontics, Il San, Kyung-Gi Province, Korea.
§Clinical Instructor, Department of Dentistry/Oral and Maxillofacial Surgery, College of Medicine, Hanyang University, Seoul, Korea.
∥Postdoctoral Fellow, Department of Applied Mathematics, University of Colorado, Boulder, CO.
¶Assistant Professor, Department of Dentistry/Oral and Maxillofacial Surgery, College of Medicine, Hanyang University, Seoul, Korea.
Address correspondence and reprint requests to Dr Hwang: Department of Dentistry/Oral and Maxillofacial Surgery, College of Medicine, Hanyang University, #17 Haengdang-dong, Seongdong-Ku, Seoul, 133-792, Korea
ABSTRACT