不同基底冠材料对上颌中切牙全瓷冠受载应力分布的影响

目的：研究上中切牙不同基底冠材料全瓷冠受载时的应力分布特点。方法：运用逆向工程软件构建上颌中切牙全瓷冠（双层冠结构）的三维有限元数值模型,选择氧化锆全瓷冠、氧化铝全瓷冠为实验组,贵金属烤瓷冠为对照组,施以不同部位静态载荷模拟加载,分析其应力分布趋势的异同。结果：应力分布云图显示,不同基底冠材料的全瓷冠应力分布趋势相同,载荷区和全冠颈缘为应力集中区,其中应力极值点位于载荷点。不同基底冠材料全瓷冠的应力值不同,随着材料弹性模量的增加,基底冠的等效应力极值相应增加,而饰面瓷则适当减小;基底冠弹性模量的增加也会使得基底冠与预备体界面、基底冠与饰面瓷界面以及邻面颈缘的张应力显著提高,饰面瓷的张应力则稍有下降。结论：高弹性模量基底冠可降低上中切牙全瓷冠饰面瓷的折裂风险。

The effect of different core materials on the stress distribution in layered crown of the upper incisor

Objective：To investigate the stress distributions in an all-ceramic crown of the upper central incisor with different core ceramics under load.Methods：The 3-dimensional finite element model of layered crown was constructed using CAD software.This crown model was made with gold,zirconia,and alumina core and veneering porcelains.A loading simulating the maximum bite force （ 200 N） was applied to the crown at different locations（ incisal edge,lingual fossa,lingual margin） .The stress values of full crown was calculated and expressed,as stress intensity,in MPa.Results：The simulation showed that,the tendency of stress distributions in an allceramic crown with different core materials was similar.The MPS（ maximal principal stress） value was located in the region submitted to the load and the proximal margin.As the elastic modulus of core materials increased,the maximal stress value of von Mises in veneer decreased,however that in core increased.Moreover,the MPS in core/veneer interface,core/tooth preparation interface,and proximal margin increased,but the MPS in veneer decreased.Conclusions：The use of core materials with high elastic modulus would reduce the risk of veneer chipping.