双侧下颌支矢状劈开截骨术后患者可施加合适咬合力的数值研究

双侧下颌支矢状劈开截骨术在临床手术中广泛用于治疗缩颌、凸颌和颌面不对称患者的颌面畸形症状。本文用数值方法研究双侧下颌支矢状劈开截骨术并前移下颌骨后患者可施加的合适咬合力。首先，用缩颌患者的CT断层扫面数据建立下颌骨、关节盘、关节窝和相关软组织的高度几何相似性的几何模型；然后，用有限元模型模拟双侧下颌支矢状劈开截骨术后患者的咬合过程。通过分析发现，术后关节盘上的位移处于正常的范围，而应力却远远超过正常范围，因此，将应力因素作为确定术后患者可施加的合适咬合力的标准。当施加正常咬合力的25%时，关节盘上的应力分布和术前没有显著性差异，同时下颌骨上的应力水平也处于正常范围。

Numerical study of suitable occlusal forces after mandibular advancement surgery with bilateral sagittal split ramus osteotomy

The bilateral sagittal split ramus osteotomy (BSSRO) has been widely used in orthognathic surgeries and become a common surgical treatment for mandibular prognathism,retrognathism and asymmetry. This paper numerically investigates the suitable occlusal forces that patients are allowed to apply after mandibular advancement surgery with BSSRO.Computed tomography (CT) scan images of a retrognathia patient are assembled to build a high resolution geometric model including the mandible,articular discs,the glenoid fossa and related tissues,then the BSSRO virtual surgery is carried out.The numerical analysis results show that the displacements on the articular discs maintain a normal level,while the stress pattern exceeds the normal level largely.Therefore,the suitable occlusal forces can be determined by the criterion of sustaining a normal stress level on the articular discs. The location changes of the maximum stress on the post-operative articular disc are identified by the comparison with that on the pre-operative one.When 25% of the normal occlusal forces are applied after the surgery,there is no significant difference in the stress level between the post-operative articular discs and the pre-operative ones,and the stress in the mandible is also within a normal range.