功能状态下无牙颌患者髁状突的应力分布研究

目的构建无牙颌包括下颌骨的颞下颌关节(TMJ)三维有限元模型;探讨戴用全口义齿无牙颌患者在牙尖交错位紧咬牙时颞下颌关节髁状突的应力分布特征。方法以活体人颅为标本,采用螺旋CT断层扫描技术,图像数字化处理等方法在计算机上构建模型,然后在载荷状态下,利用ANSYSV8.0软件进行运算分析。结果建立了无牙颌下颌骨和颞下颌关节三维有限元模型,并在此模型后牙相应位点加载、运算、分析显示:髁突近颈部应力力值明显大于近顶区;前、后斜面由外向内力值逐渐减小;外、内侧由前向后力值逐渐减小,前斜面、外侧上1/2(近髁突顶)区域压应力占主导地位,下1/2(近颈区)区域以拉应力为主,下外侧为主要应力集中区;后斜面及内侧上1/2以拉应力为主,下1/2以压应力为主。结论戴用息止间隙为2mm的全口义齿无牙颌患者,髁状突各区域拉、压应力并存,但每个区域应力分布特征及水平有较大差异;前斜面外侧即关节功能区应力水平明显高于其他区域,符合正常人TMJ功能的特点。

Three-dimensional finite element stress analysis of temporomandi bular joint of edentulous jaw

Objective To construct a temporomandibular joint (TMJ) model including mandible by means of three-dimensional finite element methods and to investigate the stress distribution of the condyle during clenching of edentulous jaw with complete denture.Methods The three-dimensional model (3-DFEM) of TMJ including mandible of edentulous jaw patient was constructed by helix-CT scanned transverse sections.The stress distribution of the condyle was analyzed under load.Results The three-dimensional finite element model of TMJ including mandible of edentulous jaw was established,then loaded and calculated on the corresponding situs of posterior tooth of the model.Analytic results showed the stress on the neck of condyle obviously surpassed that on the top of condyle.The stress decreased from external to interior on anterior and posterior incline,and decreased from anterior to posterior on interior and external incline of the condyle.Compressive stress was dominant in the anterior incline and upper 12 of lateral part (near the top of the condyle),and tensile stress was dominant in the inferior 12 (near the neck),so the lateral inferior part was featured by high stress distribution.In the posterior and interior part,tensile stress occupied the upper 12 and compressive stress was main in inferior 12.Conclusion The edentulous jaw of patients had the compressive stress and tensile stress simultaneously on the whole condyle.But the stress is different in level and feature of distribution.The external anterior incline is featured by the highest stress distribution,and it is consistent with the feature of the TMJ of healthy people.