一侧下颌角受力对双侧关节盘及髁突软骨的影响

目的:利用三维有限元分析法,从生物力学角度探讨一侧下颌角受力瞬间双侧颞下颌关节(TMJ)关节盘及髁突软骨的相应变化及其与临床实际的关系。方法:建立下颌骨和TMJ共5个不同开口度(闭口位及1、2、3、4cm开口位)的三维有限元数字模型;于左侧下颌角下缘向上,施以与眶耳平面垂直的1000N压力。获取受力后双侧关节盘和髁突软骨产生的平均主应力的分布及其峰值大小。结果:(1)闭口位时,双侧关节盘和髁突软骨的平均主应力(EQV应力)峰值明显较小;(2)在不同开口位,关节盘EQV应力峰值多位于后带,髁突软骨则多位于前斜面;(3)关节盘EQV应力峰值始终是左侧大于右侧,而髁突软骨在闭口位及1、4cm开口位时左侧EQV应力峰值大于右侧,2、3cm开口位时则是右侧大于左侧;(4)双侧关节盘和髁突软骨的EQV应力峰值出现的部位基本对称。结论:(1)本组模型较精确地反映了实物,并且实验结果与临床实际相接近,解决了以往实验中遇到的一些问题,为TMJ的生物力学研究提供了新的途径。(2)稳定的咬合关系可以明显减小TMJ的间接损伤。(3)关节盘后带病变及髁突器质性病变可能由下颌骨一次性暴力创伤后造成的TMJ间接损伤引起;受力侧关节盘比对侧更易受损伤,而双侧髁突软骨都有受到严重损伤的可能。

A finite element analysis of bilateral articular disks and cartilage with force at the unilateral mandibular angle

PURPOSE:To study the stress variation in bilateral articular disks and articular cartilage while forces were applied in the left mandibular angle by 3D finite element analysis,and to study its relationship with clinical situations.METHODS:The mandible and temporomandibular joint(TMJ)3D finite element models at five mouth openings(closed,1cm,2cm,3cm and 4cm in the range of mouth opening)were constructed.1000N forces that formed an angle of 90 o to the frankfort plane were applied to the left mandibular angle.The Von Mises stress(equivalent stress,abbreviated EQV stress)distribution and maximum EQV stress were used to display the stress in the articular disk and articular cartilage.RESULTS:(1)The force affected little effect on each side of the TMJ in closed position.(2)In all mouth openings,the maximum EQV stresses mostly appeared at the posterior band of the articular disc,and mostly appeared at the anterior oblique surface of the articular cartilage.(3)The maximum EQV stresses on the articular disc of the left side were always higher than the right side.The maximum EQV stresses on the articular cartilage of the left side were higher than those of the right side in closed,1cm and 4cm mouth opening positions,but lower in the 2cm and 3cm opening positions.(4)The locations of the maximum EQV stress on articular disk and articular cartilage of each side were symmetrical.CONCLUSIONS:(1)Our models precisely corresponded with real TMJ and mandible,and the results of this study corresponded with the clinical situations well.(2)TMJ could be protected by stable occlusion position on mouth closing.(3)Mandible trauma might be the reason that most articular disc diseases occur at the posterior band and most condylar process diseases occur at the anterior oblique surface;the articular disk of the forced side were easily injured than the other side;the articular cartilage of both sides might be severely injured.Supported by Natural Science Foundation of Shanxi Province(Grant No.2004C2-65).