Lin Chun-Li, Chang Yen-Hsiang, Chang Chia-Yu, Pai Che-An, Huang Shao-Fu
Department of Mechanical Engineering, Chang Gung University, Tao-yuan, Taiwan.
Eur J Oral Sci. 2010 Feb;118(1):87-93. doi: 10.1111/j.1600-0722.2009.00704.x.
The present study evaluated the failure risks of an endodontically treated premolar with severely damaged coronal hard tissue and restored with either a computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic endocrown or a classical crown configuration. Two, three-dimensional finite element maxillary premolar models were designed with endodontic treatment and restored with either a chairside economic reconstruction of esthetic ceramic (CEREC) ceramic endocrown or a classical crown. The Weibull function was incorporated with finite element analysis to calculate the long-term failure probability relative to different load conditions. Additionally, an in vitro fatigue-load fracture experiment was performed to validate the numerical simulation results. The results indicated that the stress values on the dentin and luting cement for the endocrown restoration were lower than those for the crown configuration. Weibull analysis revealed that the individual failure probability in the endocrown dentin and luting cement diminished more than those for the crown restoration. While the overall failure probabilities for the endocrown and the classical crown were similar, fatigue fracture testing revealed that the endocrown restoration had higher fracture resistance than the classical crown configuration (1,446 vs. 1,163 MPa). This investigation implies that the endocrown can be considered as a conservative, aesthetic, and clinically feasible restorative approach for endodontically treated maxillary premolars.
本研究评估了牙冠硬组织严重受损的经根管治疗的前磨牙，采用计算机辅助设计/计算机辅助制造（CAD/CAM）陶瓷内冠或传统冠修复后的失败风险。设计了两个三维有限元上颌前磨牙模型，进行根管治疗后，分别用椅旁经济型全瓷修复体（CEREC）陶瓷内冠或传统冠进行修复。将威布尔函数与有限元分析相结合，以计算相对于不同载荷条件下的长期失败概率。此外，还进行了体外疲劳载荷断裂实验，以验证数值模拟结果。结果表明，内冠修复体在牙本质和粘结水门汀上的应力值低于传统冠修复体。威布尔分析显示，内冠牙本质和粘结水门汀的个体失败概率比传统冠修复体降低得更多。虽然内冠和传统冠的总体失败概率相似，但疲劳断裂测试表明，内冠修复体比传统冠修复体具有更高的抗断裂性（1446对1163兆帕）。本研究表明，对于经根管治疗的上颌前磨牙，内冠可被视为一种保守、美观且临床可行的修复方法。
