背景：髁突骨折可以发生在直接及间接外力作用下，其危险性与撞击作用部位有着何种相关关系，目前报道较少。目的：快速建立正常下颌骨的三维有限元模型，采用有限元方法分析下颌骨不同部位受力对髁突力学应变情况。方法：以颌骨发育正常，无任何口腔疾患的青年志愿者1例进行多层螺旋 CT扫描，利用医学逆向工程软件Mimics和大型有限元软件MSC.Patran建立下颌骨三维有限元模型并对下颌骨体部、颏部、下颌角部及髁突等部位进行数值撞击试验，对所建模型进行可行性验证。结果与结论：①快速建立下颌骨三维有限元生物力学模型，重现了下颌骨的几何外形，能够得到下颌骨髁突的直观整体印象。建立的几何模型包括80044节点和18441单元。②于下颌骨颏部、一侧下颌体部、下颌角及髁突处分别加载100 N压力时，骨皮质中最大等效应力出现在髁突区域，髁突发生骨折的危险性最大。实验结果有助于从力学上对于髁状突骨折类型进行分析及对骨折的程度进行判断。%BACKGROUND:Condylar fracture can occur under direct and indirect forces, and however, its risk and correlation with the impact site are rarely reported. OBJECTIVE:To quickly establish normal mandible three-dimensional finite element model and to analyze the strain conditions of the condyle under force at different parts of the mandible. METHODS: An adolescent volunteer was examined by multilayer spiral CT scans, whose mandible was normal and oral cavity was healthy. We used the reverse engineering software Mimics and large finite element software MSC.Patran to establish the three-dimensional finite element model of the mandible and to verify the feasibility of the model in the impact test at the body of the mandible, chin, mandibular angle and condyle. RESULTS AND CONCLUSION:A rapid establishment of mandible dimensional finite element biomechanical model could reproduce the morphology of the mandible, which was able to obtain the overal visual impression of the mandibular condyle. Geometric model included 80 044 nodes and 18 441 units. The mandibular chin, one side of the body, mandibular angle and condyle were given 100 N force respectively. The maximum equivalent stress of the bone cortex appeared in condylar region. So the mandibular condylar fractures were at the greatest risk. Experimental results contribute to mechanicaly analyze the condylar fracture type and to judge the severity of fractures.
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