Three-dimensional Cephalometry, Serum Creatine Kinase Detection And Three-dimensional Finite Element Vitodynamics Analysis Of Mandibular Angle Osteotomy

Objective:To understand the changes of facial morphology and facial physiologicalfunction induced by mandibular angle osteotomy.Method:1. 102 cases of prominent mandibular angle patients who were performedmandibular angle osteotomy in Plastic Surgery Hospital were examined bythree-dimensional CT and three-dimensional cephalometry were carried out. 55 casesof patients were selected from these patients by 95％confidence intervals of intermandibular angle distance and angle of mandibular angle. Their cephalometric resultswere handled by SPSS12.0 and difference between normal female cohort andprominent mandibular angle female cohort were found out.2. 18 cases of prominent mandibular angle patients were selected in random andtheir craniofacial structure were examined by three-dimensional CT preoperative andpostoperative. Their cephalometric results were handled by SPSS12.0 and differencebetween preoperative cohort and postoperative cohort were found out.3. 20 cases of female patients who were performed mandibular angle osteotomywere selected in random. An own control clinical experiment was employed.Haemospasia was performed preoperative, intraoperative, 3 days, 7 days, 1 month and3 month postoperative and serum creatine kinase activity was examined by automaticdetection instrument.4. A prominent mandibular angle patient without orthodontics deformity wasselected in clinical. She was examined by three dimensional CT preoperative and 3month postoperative. Preoperative and postoperative three dimensional finite elementmodels were established by dicom data transformed by Mimic software and Ansys software. Most powerful bite working condition and impact condition were simulatedon finite element model by preprocessing. Static stress analysis and transient dynamicstress analysis were carried on preoperative and postoperative finite element model.Result:1. All patients' three-dimension data about craniomaxillofacial structures wereobtained by three-dimensional cephalometry. There are significant difference ofcraniofacial structure between prominent mandibular angle female cohort and normalfemale cohort.2. Significant differences were found in angle of mandibular angle, mandibularangle distance, width of mandibular angle, length of ramus, ectropin angle ofmandibular angle,∠Go-Me-Go and width of face and masseter muscle volumebefore and after mandibular angle osteotomy.3. Acute increase of creatine kinase activity was found during operation, after atransient decrease of 7 days, a permanent increase of creatine kinase activity lastedabout 3 month.4. In static stress analysis, the stress peak and stress maximal value point ofmandibule are basically at equal pace between preoperative model and postoperativemodel. In transience dynamic stress analysis, although stress discrepancies are foundin part time point and some region of mandibule between preoperative model andpostoperative model, but direction and topography of main stress are basically atequal pace. Main stress distributes beside external oblique line and concentrates at theneck of condyle. There are no significant difference of stress conduction anddistribution between preoperative model and postoperative model.Conclusion: There are significant difference of craniofacial structure betweenprominent mandibular angle female cohort and normal female cohort. The measurevalue reduced and closed to normal cohort after mandibular angle osteotomy. Increaseof creatine kinase activity may concern with atrophy of masseter muscle. By threedimensional finite element analyses, no significient difference was found about staticstress analysis between preoperative model and postoperative model. In transientdynamic stress analysis, althrough some difference about stress transmission and stress rejection are found between preoperative model and postoperative model, butthere are no significant changes about main stress and no significant changes ofvitodynamics of mandibule induced by mandibular angle osteotomy.