下顎枝矢状分割法術後の安定性および安定性に影響する因子に関する研究

SNB

北海道歯学会

北海道歯学雑誌

We have created our own team, recruiting prosthodontists, to achieve a desirable and functional occlusion since 1972. We believe that long-term stability is one of the most important evaluation items which appraise successful orthognathic treatment. From the standpoint of our previous experiences, postoperative stability was clinically fine. However, statistical evaluations have not sufficiently been performed yet. This study is performed to evaluate the dentofacial changes in the case requiring setback movement by sagittal split ramus osteotomy (SSRO) and clarify the contributing factors for postoperative stability. Out of 306 patients, 31 patients met the inclusion criteria. Measurements were performed on the lateral cephalogram taken at just before and after surgery, and sequentially at the period of 6 month, 1-year and 3- year postoperatively. Thirteen cephalometric parameters (7 angular and 6 linear) were selected. At 6-month postoperatively, ANB and point B were significantly changed, and they were stable after then. Other measurements than ANB and point B were stable completely throughout the follow-up period. In the multivariate analysis, SNB change produced by surgery was significantly related to the postoperative stability. SNB will change back to original value. Regression formula was obtained as β= -1.31-0.54α (α : Angular change of SNB in surgery(°), β= Liner horizontal change of point B at 3 years after surgery (mm)). It suggests that vertical change is also a contributing factor which predicts postoperative stability in addition to the amount of direct horizontal liner movement by surgery.