下颌骨囊性病变的三维有限元模型生物力学分析

目的 对下颌体部囊性病变三维有限元模型行生物力学分析，为临床制定手术方案提供参考依据。方法 基于牙颌关系正常健康女性志愿者的下颌骨CT图像，构建出下颌体部囊性病变三维有限元模型，分析在一定约束及载荷条件下病变区接近应 力峰值时囊肿大小及剩余骨壁情况。结果 当囊肿大小为37.63 mm×11.32 mm×21.45 mm时，病变区最大Von Mises应力值达到77.295 Mpa，接近于下颌骨的屈服强度，存在病理性骨折的风险，此时病变区颊、舌侧及下颌骨下缘剩余骨厚度分别为1.52、0.76、1.04 mm。结论 剩余骨量是影响囊性病变刮治术后病理性骨折的重要因素，当下颌体部囊性病变区各壁剩余骨皮质厚度低至1mm时，此界值可作为临床制定一期开窗减压治疗联合二期刮治术式的参考依据。

Biomechanical study of cystic lesions of the mandible based on a three-dimensional finite element model

Objective To analyze the biomechanics of cystic lesions in the mandibular body in a three-dimensional (3D) finite element model. Methods A 3D finite element model of cystic lesion of the mandibular body was constructed based on the CT images of the mandible of a healthy adult female volunteer with normal occlusion. The size of the cyst and the residual bone wall were analyzed when the lesion area approached the stress peak under certain constraints and loading conditions. Results When the size of the cyst reached 37.63 mm×11.32 mm×21.45 mm, the maximal von Mises stress in the lesion area reached 77.295 MPa, close to the yield strength of the mandible with a risk of pathological fracture. At this point, the remaining bone thickness of the buccal and lingual sides and the lower margin of the mandible in the lesion area was 1.52 mm, 0.76 mm and 1.04 mm, respectively. Conclusion Residual bone mass is an important factor to affect the risk of pathological fracture after curettage of cystic lesions. A thickness as low as 1 mm of the residual bone cortex in the cystic lesion area of the mandibular body can be used as the threshold for a clinical decision on one-stage windowing decompression combined with two- stage curettage.