Forsus矫治力前导下颌有限元仿真及最佳施力角度探讨

Finite element analysis on submaxilla anterior guidance subjected to Forsus and optimal angle of orthopedic force

目的研究在Forsus矫治力作用下下颌骨的应力分布情况和位移分布情况,探讨最佳的施力角度,为临床设计新的矫治器提供生物力学基础。方法选择临床恒牙安氏Ⅱ类远中错志愿者,运用螺旋CT扫描技术及三维影像技术完成初步重建,利用Abaqus软件建立下颌骨、牙列和弓丝托槽的三维有限元模型,并在此基础上模拟临床Forsus施力部位加载,并设计了5种不同的计算工况。结果在5种工况下,弓丝托槽和牙列上的VonMises等效应力水平相对于下颌骨较高,最大应力出现在弓丝托槽。下颌骨上的应力集中主要位于髁突颈和牙槽嵴部位,下颌骨上最大的Von Mises等效应力出现在髁突颈处,下颌骨最大的位移都基本出现在颏部,髁突颈局部发生了塑性变形。结论Forsus矫治力的加载角度最好为0°～25°。

Objective To explore the stress and displacement distribution of submaxilla subjected to Forsus, and investigate the optimal angle of orthopedic force in order to provide biomechanical basis for new appliances designation. Methods A health 12-year-old clinical volunteer with Angle class Ⅱ malocclusion was subjected. Helical CT and 3-D image technique were used to finish the primary model reconstruction. And a 3-D finite element （FE） model of the submaxilla, dentition and archwires and brackets was constructed with ABAQUS software. Then Forsus orthopedic force application based on the FE model were simulated under 5 different designed conditions. Results Under all 5 loading conditions, the Von Mises equivalent stresses level on the dentition and archwires and brackets are higher than on the submaxilla, the highest stress was on the archwires and brackets. Stress centralization on the submaxilla mostly located at the condylar and alveolar ridge, the highest stress of the submaxilla was on the condylar, and the largest displacement of submaxiUa was on the chin basically. Plastical strain were appeared on the condylar. Conclusion The optimal angle of ortho- pedic forsus force is between 0° and 25°.