犬下颌骨单侧不全截骨牵张时牵张侧位移状况有限元分析

Displacemental analysis with finite element method of distractional side of canine mandible in case of distraction osteogenesis with unilateral incomplete osteotomy

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牵张侧各部分位移状况。方法有限元模型模拟犬下颌单侧不全截骨牵张,观察当滑动骨块未被牵开和被牵开时牵张侧关节、下颌角、喙突及牙齿等6个标志点的位移状况。结果下颌滑动骨块未被牵开时牵张侧第五臼齿、髁状突前斜面前缘中点所受最大主应力为压应力,髁状突后斜面后缘中点为拉应力,各标志点在空间X、Y、Z三轴位移不明显;当下颌骨滑动骨块被牵开1 mm时,上述各点位移明显增加。结论从牵张侧观察,牵张侧下颌骨在矢状平面上和冠状平面上都有以髁突顶点(横嵴中点)为中心的逆时针旋转趋势。

Objective To analyze the displacemental condition on the distractional side in the case of distraction osteogenesis with unilateral incomplete osteotomy.Methods The method of finite element analysis was used to simulate distraction osteogenesis with unilateral incomplete osteotomy.The displacemental condition of the six marked points such as the TMJ,the angle of mandible,coracoid process and teeth etc,was observed on distractional side when the transport disc was distracted without a distance and with a distance.Results On the side of distraction when the transport disc was distracted without a distance,the major principal stress of the fifth cheek tooth,the principal stress on the anterior edge midpoint of anterior slope of condyle process was press stress and the principal stress on the posterior edge midpoint of posterior slope of condyle process was pull stress.Displacement of marked point in 3 dimensions（X、Y、Z axis）was not obvious.Displacement of marked point increased obviously when the unilateral incomplete osteotomy was distracted 1 mm.Conclusions When distracted and looked from distractional side,the mandible has the trend of contrarotation on the center of the transverse ridge midpoint of condyle process on the sagittal and coronary planes.