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目的    通过建立下颌后缩三维有限元模型，探讨并分析Forsus矫治器在不同作用力值和不同作用方向对上、下颌骨位移及应力分布的影响。方法    2008年6月于西安交通大学口腔医院正畸科选取1例13岁骨性Ⅱ类下颌后缩女性患者，采用Mimics和Ansys软件结合CT技术建立该患者颌面部骨骼的三维有限元模型，模拟Forsus矫治器的作用方式在模型上进行两种加载，分别为大小不同的3组力值和方向不同的3组力值，观察颌骨和牙齿上标志点的三向位移及应力分布情况。结果    两种加载方式的3个不同加力组之间的位移差异均有统计学意义。结论    生长发育高峰期过后的患者可适当增加Forsus矫治器力值；高角、长面型患者应尽量减小Forsus矫治器作用角度。

Biomechanical study on the effect of the Forsus appliance on jaws

Objective To discuss the effect of the Forsus appliance with different loading values and different angles on the displacement and stress of the jaws, by the construction of a 3-D finite element model of a mandible retrusion patient. Methods Based on the CT technique, a 3-D finite element model for the jaw bones of the mandibular retrusion was set up with the software Mimics and Ansys. Two applications of loading were simulated on the model： three loadings with different values and three loadings with different angles. Then observe the displacement and the stress distribution of the marking points. Results The differences of the displacement among the three groups by the two applications were meaningful. Conclusion The patients who pass the peak of the growth and development could endure higher Forsus load properly. And Forsus loading with smaller angle is suitable for the patient with a steep mandibular plane and long-face.