Recurrence Rate after Angle Splitting Ostectomy

Park, Eun Je; Kim, Yong Ha; Seul, Jung Hyun

Abstract

For the treatment of the square mandibular angle, the angle splitting ostectomy method is known to have many advantages compared to the conventional angle ostectomy procedure. The splitting method is easy to proceed even for the patients with inverted angle. Better results could be achieved in the lateral profile as well as the anterior view. And this method has less complications such as bleeding, asymmetry and subcondylar fracture. However, there seems to be some doubts about the long-term results because of bone remodeling concept; the new bone could easily grow on the remained cancellous bony surface and prominence could recur on the mandibular angle area. The purpose of this study is to identify the amount of the regrowth on the ostectomized surface. We performed angle contouring surgery in fifty-one patients with wide and squared lower faces for 5 years. Of these patients, we selected 22 patients who fulfilled following categories; (1) those who had angle splitting ostectomy surgery in our institute, (2) those who had preoperative and postoperative CT examinations. The patients were classified into 3 groups. In the group 1, the follow-up CT was checked within 1 month after surgery (n=11). Group 2 included those who had CT examination during 4~6 months after surgery (n=8). In the group 3, the CT was checked more than 1 year after surgery (n=3). We identified one point (Point B) to examine the most possible point on angle of mandible (Point A: a point that 3.5 cm distance from sigmoid notch on parallel line to the posterior border of ramus at sigmoid notch , Point B: a point that 1 cm distance from Point A). We analyzed the preoperative, postoperative thickness of point B using 3 dimensional CT for detecting recurrence rate of cortical bone. The measurement was 8.43 mm before operation, and follow up measurements were 4.92 mm in group 1, 4.84 mm in group 2, and 5.27 mm in group 3, respectively. There was no statistical significant evidence of bony regrowth and recurrence from remaining surface among the groups. In the morphological comparisons, the cortical bone started to appear on the remaining angle in group 2 and covered whole the surface of angle in group 3. We concluded that the surgical procedure of angle splitting ostectomy is a long-term effective and stable method.