下颌升支矢状截骨术后下颌角宽度改变的有限元研究

Finite element study of the mandibular angle width changes in retrogression surgery by bilateral sagittal split ramus osteotomy

目的通过建立下颌骨三维有限元模型，模拟下颌不同后退距离在咀嚼肌加载时对近心骨段宽度的影响。 方法将1例颅骨模型的DICOM数据导入计算机，辅助MIMICS及ANSYS软件，逆向生成包含颞下颌关节及牙列的下颌骨模型，模拟下颌升支矢状截骨术（BSSRO）不同后退距离下，咀嚼肌早期加载时近心骨段的位移变化。 结果BSSRO术中远心骨段后移3 mm、8 mm时，近心骨段增宽均值为2.955 mm和3.490 mm，但二者间差异无统计学意义（P＝0.131）。同时，位移图示在近心骨段尤其是下颌角区域发生了明显的外翻移位，且从外向内位移值逐渐递减。结论BSSRO术后即刻下颌角增宽比较明显，咀嚼肌加载及单皮质固定系统对近心骨段的增宽有重要促进作用，但增宽的效应与下颌骨远心骨段后退的距离无显著关系。

0bjective：To establish a three-dimensional finite element model of mandible and study the transverse displacement of proximal segment after Bilateral Sagittal Split Ramus Osteotomy （BSSRO） with different retrogression amounts during mastication.MethodsDICOM data of a skull model were processed with MIMICS and ANSYS software, reconstructing the 3D model including the teeth and temporomandibular joint in order to simulate BSSRO and evaluate the transverse displacement of proximal segment with different retrogression amounts during mastication.ResultsThe mean of proximal segment width change were 2.955 mm and 3.490 mm, when retrogression amounts of distal segmentwere 3 mm and 8 mm, respectively.No significant difference between the two groups were found （P=0.131）. Meanwhile the displacement color scale of the 3D finite element models showed that the apparent transverse displacement distribution of the proximal segment was measured around the gonial area, decreased from the exterior to the interior.ConclusionsThe mandibular angle width was significantly expanded right after BSSRO. The masticatory muscle system and single cortical fixation system played an important role in expanding the width of proximal segment. However there was no correlation between the widening effect and retrogression amounts of distal segment of mandible.