Shu Jing-Heng, Yao Jie, Zhang Yuan-Li, Chong Desmond Y R, Liu Zhan
Key Lab for Biomechanical Engineering of Sichuan Province, Sichuan University, Chengdu School of Biological Science and Medical Engineering, Beihang University, Beijing, China Engineering Cluster, Singapore Institute of Technology, Singapore, Singapore.
Medicine (Baltimore). 2018 Jun;97(25):e11204. doi: 10.1097/MD.0000000000011204.
The aim of this study is to compare the differences in the stress distributions in the temporomandibular joints (TMJs) of the patients with facial asymmetry before and after bilateral sagittal split ramus osteotomy (BSSRO) under the symmetric occlusions using the three-dimensional (3D) finite element method.Ten facial asymmetry patients (Preoperative group, age 24.6 ± 4.8 years) and 10 asymptomatic subjects (Control group, age 26.8 ± 4.9 years) were recruited. After the patients underwent BSSRO, they were further assigned as the Postoperative group. 3D geometries of the finite element models of the mandible, disc, maxilla, and teeth were reconstructed according to cone-beam computed tomography (CBCT) image data. Contact elements were used to simulate the interaction of the disc-condyle, disc-temporal bone, and upper-lower dentition. The muscle forces and boundary conditions corresponding to the central and anterior occlusions were applied on the models of the 3 groups. The finite element models were validated with experimental data showing the accuracy of the simulation results.The simulation predicted preoperative significant differences of stresses between non-deviated sides and deviated sides were disappeared after the surgery under the central and anterior occlusions (P < .05). Almost all stresses in the patient models had significantly decreased after BSSRO, leveling it to the stress values of the normal subjects. Moreover, the simulation results coincided with the clinical cases which showed that BSSRO had helped to release or remove the signs and symptoms of temporomandibular disorders (TMD).In conclusion, BSSRO could correct the asymmetric stress distributions of TMJs and decrease the magnitude of the stresses for the patients with facial asymmetry. Those decreases also associated with the recovery of TMD.
本研究旨在采用三维（3D）有限元方法，比较面部不对称患者在双侧矢状劈开下颌支截骨术（BSSRO）前后，在对称咬合情况下颞下颌关节（TMJ）应力分布的差异。招募了10名面部不对称患者（术前组，年龄24.6±4.8岁）和10名无症状受试者（对照组，年龄26.8±4.9岁）。患者接受BSSRO后，进一步分为术后组。根据锥形束计算机断层扫描（CBCT）图像数据重建下颌骨、关节盘、上颌骨和牙齿的有限元模型的3D几何形状。使用接触单元模拟关节盘-髁突、关节盘-颞骨和上下牙列之间的相互作用。将与正中咬合和前伸咬合相对应的肌肉力和边界条件应用于三组模型。有限元模型通过实验数据验证，表明模拟结果准确。模拟预测，在正中咬合和前伸咬合情况下，术前非偏斜侧和偏斜侧应力的显著差异在手术后消失（P<0.05）。BSSRO后，患者模型中的几乎所有应力均显著降低，使其与正常受试者的应力值持平。此外，模拟结果与临床病例相符，表明BSSRO有助于缓解或消除颞下颌关节紊乱病（TMD）的体征和症状。总之，BSSRO可以纠正面部不对称患者TMJ的不对称应力分布，并降低应力大小。这些降低也与TMD的恢复相关。
