种植体支抗前牵上颌体的三维有限元分析

3-D finite element study on maxillary body protraction using implant anchorage

目的：探讨对上颌种植体支抗施加不同大小和方向的前牵引力时颅面复合体骨缝处的应力变化。方法：用螺旋cT扫描安氏Ⅲ类患者颅面部以获取原始二维图像DICOM数据，建立颅面复合体的三维有限元模型，种植支抗设计在32J23间。模拟前牵引力值1～10N，1N递增，方向平行于眶耳平面向前下呈0°～60°，10°递增，两两组合共70种工况。分析各工况下颅面复合体各骨缝处第一主应力及Von Miese等效应力分布情况。结果：牵引角度相同力值不同时，各骨缝应力变化规律相同；牵引力值相同角度不同时，不同区间各骨缝应力变化不同。当牵引角度小于30°时，应力变化分析提示上颌体向前生长并向上旋转；等于30°时上颌体出现向前生长；在40°～50°时，上颌体向前生长方向与牵引方向大致相同；大于50°时，上颌体出现向前生长并向下旋转。结论：种植体支抗眶耳平面向前下30°～50°牵引加载力1～10N利于上颌体向前生长。

Objective： To explore the stress change rule of craniofacial bone suture and the interface of bone-implant against differ- ent strength and direction of protraction on the implant anchorage in alveolar bone. Methods：The original DICOM data of 2-D image of craniofacial complex were obtained by high resolution CT scanning. 3-D finite element models of craniofacial complex were devel- oped according to the DICOM data. Forces of 1 - 10 N inclined at 0 -60° to Frankfort horizontal plane in the anterior and inferior di- rections were respectively applied on the implant anchorage in the alveolar bone at 32123 . Data of principle stress and Von Mises Stress of each mode of each simulaton was caculated. Results ： The change rule of the effectiveness of different force value of protrac- tion in the same direction was the same in different stress zone; that of the same force value of the protraction in differente direction differed in different stress zone. When the protraction angle was less than 30°, the maxillary complex will spin up. In the 30°, the maxillary complex showed the forward growth. Between 40°-50°, the growth direction was the same with the protraction direction. When the protraction angle was more than 50°, the maxillary complex showed down spin. Conclusion： Protraction force of 1 - 10 N at 30° -50°to Frankfort horizontal plane on implant anchorage in the alveolar bone at 32 丨23 can induce maxillary complex grow for-ward.