有限元法测量犬下颌牵张成骨时非牵张侧骨位移

Measuring displacements of non-distraction side during the distraction osteogenesis for canine mandible by finite element method

目的:运用犬下颌单侧不全截骨牵张成骨有限元模型,计算下颌骨在牵张过程中非牵张侧各标志点的位移状况。方法:在Dell PrecisionTM670工作站上,运用Mimics、Magics和MARC2003软件建立犬下颌单侧不全截骨牵张成骨的有限元模型,并模拟犬下颌单侧不全截骨牵张成骨,观察当滑动骨块未被牵开和被牵开时非牵张侧关节、下颌角、喙突及牙齿等6个标志点的受力及位移状况。结果:下颌滑动骨块未被牵开时,非牵张侧不受应力的影响,在牵张侧第五臼齿、髁状突前斜面前缘中点和髁状突后斜面后缘中点所受应力较大,并且前两点所受最大主应力为压应力、后缘中点为拉应力;各标志点在空间X、Y、Z三轴位移不明显;模拟滑动骨块在截骨线处被牵开(即下颌骨滑动骨块受到牵张力后移动)1 mm,此时下颌骨的非牵张侧的上述特定标志点在空间三轴的位移明显增加。结论:在行右侧牵引时,从右侧看非牵张侧下颌骨有矢状平面上以髁突顶点(横嵴中点)为中心的逆时针旋转趋势,而在冠状平面上则表现为向牵张侧的近似平行的移动。

Objective To calculate displacement of marked points in the non-distraction side during the distraction osteogenesis for canine mandible by analyzing a finite element model of distraction osteogenesis with unilateral incomplete osteotomy. Methods Based on the working station of Dell PrecisionTM670, the Mimics, Magics and MARC 2003 software, were applied to build the finite element model of distraction osteogenesis with unilateral incomplete osteotomy. And when the sliding bone was distracted with or without a distance, the stress status and displacement of six marked points, non-distraction joint, mandibular angle, coracoid process, teeth and so on, were observed. Results When the bone was distracted without a distance, there were no stress effects in the side of non-distraction. In the side of distraction, the fifth molar, anterior edge midpoint of condyle anterior incline were under greater stress, mainly press stress, while the posterior edge midpoint of condyle posterior incline was also under greater stress, mainly pull stress. Displacements of marked points were not obvious in 3 dimensions （x, y, z axis）. When the bone was distracted with a distance of 1mm, displacements of marked points in the non-distraction side of canine mandible were obvious in 3 dimensions. Conclusion When the right is distracted, observing from the right side can find that the mandible at the nondistraction side has the trend of contrarotation round the transverse ridge midpoint of condyle process on the plane of sagittal, whereas the mandible moves approximately in parallel to the distraction side on the plane of coronary.