种植体支抗辅助快速扩大上颌的三维有限元分析

目的:利用三维有限元分析方法，对比研究牙支抗快速扩大上颌与种植体支抗辅助快速扩大上颌在相同载荷条件下上颌骨的生物力学反应，为临床提供实验依据。方法:建立上颌骨三维有限元模型。模型一为以牙齿为支抗扩弓的有限元模型；模型二为以牙齿和种植体为支抗扩弓的有限元模型。模型一与模型二均进行水平方向20N扩弓力的加载。分别计算2种加载条件下各点的X、Y、Z轴位移，评价正畸载荷下上颌骨及牙齿的应力分布和位移趋势。结果:2个模型均表现为水平方向上，腭中缝打开量前大后小；冠状面上，从牙槽骨到颅底，打开量呈底边向下的三角形。第一前磨牙和第一磨牙呈冠颊向根舌向倾斜移位。但模型二中位移差量不如模型一明显。模型二中牙齿应力值低于模型一。结论：种植体支抗辅助快速扩弓与临床常用的固定螺旋快速扩弓方法相比，宽度开展的矫形效果能够增加骨性效应，减小牙性效应，减轻了上磨牙颊倾、舌尖下垂、下颌平面开大等不利倾向。

Three dimensional finite element analysis of rapid maxillary expansion using implant anchorage

Objective To evaluate the biomechanical effect of rapid maxillary expansion(RME)with different anchorages at the same load conditions in a three-dimensional finite element model,and provide a theoretical basis for clinical application.Methods Three-dimensional finite element model of maxilla was made.In the model 1,natural teeth were used as the anchorage;in the model 2,both the teeth and the implant were used as the anchorage.Force 20 N in the Horizontal direction was loaded on model 1 and model 2,respectively,and the displacement on the X-axis,Y-axis and Z-axis were calculated.Then the stress distribution on the bone and the teeth were evaluated,and the displacement trend was depicted.Results Both the two models showed that on the cross-section the median palatine suture opened larger at the front,and on the coronal section the median palatine suture opened like a triangle with its base downward.The cown of the tooth shifted buccally while its root shifted lingually.The displacement in model 2 showed less than that in model 1,and the stress in model 2 was also lower than that in model 1.Conclusion Compared with the natural teeth,using an implant as an anchorage can increase the bone effect while reduce the tooth effect.