Abstract Sagittal split ramus osteotomy (SSRO) is the representative orthognathic surgery for the patients with mandibular prognathism. It is essential to understand the biomechanical environment of temporomandibular joint (TMJ) to analyse the effects of SSRO. This study aimed to investigate the influence of SSRO on the stress distributions in the TMJs of the patients with mandibular prognathism under symmetric occlusions. Thirteen patients with mandibular prognathism and ten asymptomatic volunteers were recruited. Finite element models of the asymptomatic, preoperative, and postoperative subjects were established, based on the CT of the asymptomatic volunteers and preoperative and postoperative scans of patients with mandibular prognathism. Contact was used to simulate the interactions between discs and articular surfaces, and between the upper and lower dentition. Muscle forces and boundary conditions corresponding to the centric and anterior occlusions were applied on the models. Under both occlusions, the maximum and minimum principal stresses of the articular disc and condyle in the preoperative group were significantly greater than those in the control group. After SSRO, the maximum and minimum principal stresses of the articular disc and condyle of the patients under both occlusions were greatly reduced, but the principal stresses of the articular disc were not significantly higher than those in the control group. Mandibular prognathism led to excessive stress on the TMJ. Severe asymmetric compression between the TMJs on both sides might cause temporomandibular disorder (TMD) symptoms. SSRO could improve the stress distribution of the TMJ and partially relieve the symptoms of TMD.

中文翻译：

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矢状分支截骨术对对称咬合下下颌前突患者颞下颌关节应力分布的影响

摘要 矢状分支截骨术（SSRO）是下颌前突患者的代表性正颌手术。了解颞下颌关节 (TMJ) 的生物力学环境对分析 SSRO 的影响至关重要。本研究旨在探讨SSRO对对称咬合下下颌前突患者颞下颌关节应力分布的影响。招募了 13 名下颌前突患者和 10 名无症状志愿者。根据无症状志愿者的CT和下颌前突患者的术前和术后扫描，建立了无症状、术前和术后受试者的有限元模型。接触用于模拟椎间盘和关节面之间的相互作用，以及上下牙列之间。对模型施加与中心和前牙咬合相对应的肌肉力和边界条件。在两种咬合下，术前组关节盘和髁的最大和最小主应力均显着大于对照组。SSRO后，两种咬合下患者的关节盘和髁的最大和最小主应力均大大降低，但关节盘的主应力不显着高于对照组。下颌前突导致颞下颌关节承受过大的压力。两侧 TMJ 之间严重的不对称压缩可能会导致颞下颌关节紊乱 (TMD) 症状。