牙尖覆盖厚度对全瓷高嵌体修复前磨牙应力分布影响的三维有限元分析

Three-dimensional finite element analysis of cuspal-coverage thickness influence on the stress distribution of all-ceramic onlay-restored premolars

目的应用三维有限元法探讨牙尖覆盖厚度对全瓷高嵌体修复前磨牙应力分布的影响,以期为临床全瓷高嵌体的设计提供参考。方法采用显微CT扫描的数据建立全瓷高嵌体修复根管治疗后上颌第一前磨牙的三维模型,设计不同牙尖覆盖厚度为2、3、4 mm的3组模型,分别施加600 N垂直载荷和200 N侧向载荷,分析高嵌体、树脂粘接剂层及牙本质的应力分布。结果随着牙尖覆盖厚度的增大,全瓷高嵌体内部的最大主应力峰值减小,粘接剂层边缘的最大主应力峰值增大,侧向载荷下冠部腭侧剩余牙本质的应力集中面积增大。结论增大全瓷高嵌体的牙尖覆盖厚度可减小全瓷高嵌体破裂的风险,但可能会导致高嵌体脱落和腭侧牙本质折裂。

Objective To investigate the influence of cuspal-coverage thickness on the stress distribution of all-ceramic onlay-restored premolars by using 3D finite element(FE)analysis and to provide references for the design of all-ceramic onlays for clinical application.Methods 3D FE models of all-ceramic onlays with three cuspal-coverage thicknesses(2,3,and 4 mm)of endodontically treated maxillary premolar were constructed based on micro-CT images.Stress distributions in the onlay,adhesive resin cement layer,and dentin of models were analyzed under vertical load(600 N)and oblique load(200 N).Results When the cuspal-coverage thickness increased,the peak maximum principal stress value decreased inside the onlay but increased in the margin of the adhesive resin cement layer.In addition,stress concentration areas increased in the coronal residual dentin on the palatal side under oblique load.Conclusion An increase in the cuspal-coverage thickness of all-ceramic onlays may reduce the risk of rupture of the restoration but may deteriorate the restoration and cause palatal dentin fracture.