Objective To illustrate the morphological changes of mandible after angle-splitting ostectomy. Methods From January 2006 to April 2008, 10 cases had undergone mandibular angle-splitting ostectomy to reduce the width of the lower face. For each patient, CT datum of mandible at three stages （preoperative, immediate postoperative, 6 months postoperative） were collected. By the application software of reverse engineering （Surfacer V9） and true-up and dissection techniques based on three-dimensional spiral computed tomography（3D-CT）, operative efficacy and bone regeneration at the operation area of angle-splitting ostectomy were evaluated 6 months postoperative. Results 1）Concavity could be seen at the angle-splitting ostectomy area 6 months postoperative, especially at the mandibular external oblique line region. Average cup depth was （3.64±1.67）mm by contrasted to preoperative. Diminution of bone volume was 55%±9% for the local operative area 6 months postoperative. 2）Bone regeneration could be seen at the area that mandibular outer cortex had been removed. Compared with immediate postoperative, ratio of neoformative bone was 84.6% ±7.3% 6 months postoperative. The main region of bone regeneration was mandibular angle. Conclusion Mandibular angle-splitting ostectomy is an effective technique for reducing the width of the lower face. Masseter muscular movement should be restricted postoperative to prevent hyperostosis at the angle area.
