单冠与联合邻牙联冠修复平龈残根的三维有限元应力分析

3D FE Analysis of Stress Distribution in Gingival Level Residual Root Restored with Single Crown and Combined Crown Plus Adjacent Teeth

采用有限元法研究不同修复方法修复后牙体及修复体应力分布,比较单冠与联合邻牙联冠修复平龈残根在不同载荷条件下的应力分布,为优化临床设计提供参考。建立包含4种单冠(S)和4种联冠(C)的有限元模型共8种,冠修复材料包括VITAMARK II(V)及Y-TZP(Y),桩材料包括玻璃纤维桩(F)和纯钛桩(T)。采用Abaqus有限元软件计算双侧对称加载100N和单侧加载200N时各部分的von Mises应力分布及峰值。双侧对称加载100N时,联冠修复与单冠修复对各部分应力分布的影响不明显;而在单侧加载200N条件下,联冠修复可改变冠内应力分布,降低桩内应力峰值,相对单冠修复能降低患侧牙本质应力,提高邻牙牙本质应力。平龈残根修复时,增加邻牙做联冠,可以有效改善应力分布,尤其是在不对称载荷条件下。

To provide guidance for clinical design, FE analysis was used to compare stress dis- tribution under different loading and boundary conditions in gingival level maxillary incisors re- sidual root restored with single crown as well as combined crown plus adjacent teeth. Eight FE models of maxillary incisors were setup, which include 4 single crowns （S） and 4 combined crowns（C）. The crown materials were divided into VITAMARK II （V） and Y-TZP（Y）, the post materials were divided into glass fiber（F） and titanium（T）. The 100 N bilateral symmetry load and 200 N unilateral load were applied at the palatal surface of the crown. Von Mises stress of dentin, post and crown were computed by Abaqus software. Its distribution and maximum value were investigated to obtain optimization design. Under 100 N bilateral symmetry load, combined crowns and single crowns did not influence the maximum value of von Mises stress in dentin, post and crown obviously. But under 200 N unilateral load, combined crowns changed the distributionof stress in crown and decreased the maximum value of Yon Mises stress in post and residual root dentin, increased it in adjacent teeth dentin. In gingival level residual root, choosing combined crown plus adjacent teeth could benefit the stress distribution, especially under asymmetry load.