不同方向的中位牵引作用下颅面部的生物力学变化

Three-dimensional finite element analysis for different directions distraction at midface

目的探讨颅面复合体在不同方向的中位前牵引作用下的生物力学变化。方法采用三维有限元法测量以梨状孔底骨性承力，不同方向中位前牵引的生物力学变化。结果随牵拉的角度增大，各观察点的矢向位移逐渐减小。垂直向移位由向上逐渐转为向下，前下20°-30°牵引可整体前移上颌，且各骨缝区应力一致，可避免上颌骨的逆时针旋转。结论以梨状孔底承力骨性前牵引，牵引方向为前下20°～30°时，可有效地前移上颌复合体。

Objective To investigate the biomechanical changes with different directions distraction at midface. Methods An anteriorly directed 500 g force was applied to the floor of apertura piriforms in different directions to the occlusal plane, Three-dimensional finite element analysis was used to evaluate the biomechanical change of craniofacial complex. Results As the force direction was moved downward, the sagittal distraction length of the craniofacial complex decreased and vertical movement changed from upward to downward. The craniofacial complex was moved anteriorly when the downward force was applied about 20 - 30 degrees to the occlusal plane. The forees could generate the uniform stress distribution in the craniofacial sutures and avoid counterclockwise rotation of the maxilla. Conclusions The craniofacial complex can be effectively distracted anteriorly when the downward force is applied to the floor of aperture piriforms in direction of 20 - 30 degrees to the occlusal plane.