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[Clinical research of angle-splitting ostectomy based on three dimensional computed tomography true-up technique].

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.