氧化锆全瓷叠层冠样结构应力分布的有限元分析

Stress distribution of dental zirconia layered structure: a finite element model study

目的分析氧化锆全瓷叠层冠样结构应力分布情况。方法在已建立的上颌第一磨牙全瓷叠层冠样结构有限元模型上,设定饰面瓷厚度1.5 mm,弹性模量70 GPa,核瓷层厚度0.5 mm,弹性模量205 GPa。在Abaqus软件中,在模型斜嵴距近中舌尖约0.5mm处,直径1 mm的圆形面积上施加与牙长轴平行的200 N静态载荷,然后,对模型各部分最大主应力进行计算,导出最大主应力云纹图及应力集中区最大主应力的值。结果进行载荷计算后,全瓷冠模型表面各节点的最大主应力各不相同,饰面瓷位于加载区形成最大的应力集中区,并产生几个次应力集中区:近中邻面边缘应力集中区、舌面应力集中区、远中邻面应力集中区、颊面应力集中区以及近中窝应力集中区。核瓷层最大应力集中区主要位于近中舌尖的内侧面,并在近中边缘形成次应力集中区。结论该分布规律与同类研究结果相似,与全瓷冠在受力下产生的失败模式的裂纹的起始部位相符合。

Objective To study stress distribution of dental zirconia layered structure.Methods On the constructed three-dimensional finite element model of zirconia layered structure of the first maxillary molar,veneer layer is 70 GPa and 1.5mm,core layer is 205 GPa and 0.5 mm,respectively.Load of 200 N was applied over a 1mm diameter circle at the tip of the mesial-distal cusp ridge,simulating typical occlusional contact areas.Then maximum principal stress was calculated.Results The maximum principal stress varied throughout the geometry of the full crown configuration.For veneer,one concentration district of maximum principal stress occurred on the occlusal surface closely proximal to the loading position,several sub-maximum principal stress areas were observed,such as,margin regions of the mesial face,lingual face,distal face,buccal face and fossa of the occlusal face.Concentration of maximum principal stress occurred in the inner-face of the core near the mesial-distal cusp,and a small maximum principal stress area was also observed at the margin of the mesial face.Conclusion The stress distribution observed is similar with other studies,and is in coincidence with clinical failure model of all-ceramic crowns.