前牙全瓷冠的循环疲劳特性及寿命分析

目的 分析全瓷冠(IPS Empres2)循环疲劳特性及寿命,为全瓷冠的临床设计、制作以及使用寿命的评估提供依据.方法 建立上中切牙及其全瓷冠的有限元模型，模拟牙尖交错(牙合)时前牙正常骀关系,在90～130 N静态载荷加载下,分析全瓷冠受力状况.根据有限元获得的应力、应变结果,使用MSC Fatigue疲劳分析软件在90～130 N循环载荷下研究全瓷冠的循环疲劳特性及寿命.结果全瓷冠唇舌侧颈部肩台为疲劳寿命最短的区域,可承受的疲劳循环次数为2 506 109～6 950 243次.前牙承担的载荷逐渐增加时,全瓷冠疲劳寿命明显降低.前牙咬合接触时间增加时,全瓷冠疲劳寿命也逐渐降低.结论全瓷冠修复对全瓷材料循环疲劳性能有较高的要求,(牙合)力对全瓷冠疲劳寿命的影响大于咬合接触时间的影响,临床应注意合理调整全瓷冠所承担的(牙合)力.

The study of cyclic fatigue and lifetime for all-ceramic crown after cementation

Objective To study mechanical and cyclic fatigue behavior of IPS Empress2 under cyclic loading, and to establish guidelines for the use and design of all-ceramic crowns. Methods A 3-D finit element method model of tooth and crown were established. The strength and lifetime of all-ceramic crowns under cyclic loading in centric occlusion were investigated using computational techniques of the Abaqus and MSC Fatigue software. Results Most of the fatigue and fracture of all-ceramic crown occurred within the veneering material at cervical marginal of the crown. The number of loading cycles before failure occurred varied within specified limits 2 506 109-6 950 243. The lifetime of the crown decreased significantly as loading increased and decreased gradually as loading time increased as well. Conclusions The mechanical and fatigue behavior of ceramic materials and restorations need to be improved before clinical use in order to guarantee clinical long-term success of all-ceramic crown. The occlusal force should be adjusted properly in order to increase the longevity of all-ceramic crowns.