The purpose of this study is to investigate the biomechanical effect of bimaxillary osteotomies on patients with mandibular retraction. Mandibular retraction, as a typical maxillofacial deformity, and has great adverse effects on TMJ. Bimaxillary osteotomies are widely used to correct symptoms of mandibular retraction. It is necessary to understand the effect of surgery on temporomandibular disc (TMJ). Five patients with mandibular retraction and 10 asymptomatic subjects were involved in this study. Finite element models of preoperative, postoperative and control group were constructed based on the CT data. Nine sets of concentrated forces were used to simulate the muscle effect and contact method was used to simulate the interaction within the TMJs and dentitions. The results showed that bimaxillary osteotomies could effectively improve the maxillofacial morphology and alleviate the overload in TMJ. The facial asymmetry and right chewing side preference could cause imbalanced stress distributions in the TMJs and interfere the surgical treatment.

中文翻译：

---

双颌截骨术对切牙咬合下下颌后缩患者的生物力学影响

本研究的目的是探讨双颌截骨术对下颌后缩患者的生物力学影响。下颌后缩作为一种典型的颌面部畸形，对颞下颌关节有很大的不良影响。双颌截骨术广泛用于矫正下颌后缩症状。有必要了解手术对颞下颌椎间盘（TMJ）的影响。本研究涉及 5 名下颌后缩患者和 10 名无症状受试者。根据CT数据构建术前、术后和对照组的有限元模型。使用九组集中力来模拟肌肉效应，并使用接触法来模拟颞下颌关节和牙列内的相互作用。结果表明，双颌截骨术可以有效改善颌面部形态，减轻颞下颌关节超负荷。面部不对称和右侧咀嚼偏向可能导致颞下颌关节应力分布不平衡，干扰手术治疗。