中文摘要：

目的：模拟磨牙根管治疗后全瓷嵌体冠修复的有限元模型,分析髓室底垫底厚度对应力分布的影响。方法：利用Micro-CT扫描数据建立离体下颌第一磨牙三维有限元模型,模拟复合邻面洞型并用嵌体冠进行修复。根据玻璃离子垫底厚度不同分为0（空白组）、1、2、5 mm（窝洞填平）组,然后分别采用轴向和45°斜向静态加载模式对模型加载280 N和105 N的力,观察不同部位的应力分布情况,分析比较应力集中部位及相应部位应力峰值的差异。结果：不同垫底厚度在相同的加载条件下,应力的集中部位相似。与0 mm组相比,当垫底厚度为1 mm,轴向加载时,髓室底的等效应力减小13.8%（45°加载时减小26.8%）,粘结层剪切应力减小1.1%（45°加载时增加1.4%）,远中肩台应力减少3.0%（45°加载时增加1.3%）;垫底厚度为2 mm,轴向加载时,髓室底的等效应力减小31.1%（45°加载时减小41%）,粘结层的剪切应力增加3.7%（45°加载时增加33.2%）,远中肩台的等效应力减小0.6%（45°加载时增加1.6%）;垫底厚度为5 mm,轴向加载时,髓室底的等效应力减小37%（45°加载时减小49.1%）,粘结层的剪切应力增加13%（45°加载时增加47.2%）,远中肩台的等效应力增加7.3%（45°加载时增加10.5%）。结论：对根管治疗后的磨牙嵌体冠修复时,较薄的垫底厚度有利于剩余牙体和嵌体冠的稳定。

英文摘要：

AIM： To evaluate the effects of cement thickness on the full-ceramic-endocrown restoration using a finite element analysis model. METHODS： A finite element analysis model of mandible first molar was established using the scanning data acquired by Micro-CT. The misio-occlusio-distal cavity and endocrown restorations were simulated. The models were lined with Fuji IX glass ionomer cement. Based on cement thickness of 0,1,2 and5 mm. A static axial and 45° loading 280 N and 105 N were respectively applied to each model. RESULTS： Compared with 0 mm group,when the glass ionomer was under 1 mm / axial condition,equivalent stress of pulp chamber floor decreased by 13. 8%（under 1 mm /45° decreased by 26. 8%）,shear stress of bonding layer decreased by 1. 1%（under 1 mm/45° increased by 1. 4%） and equivalent stress of the distal surface of the remaining tooth decreased by3. 0%（under 1 mm /45° increased 1. 3%）. Under 2 mm / axial condition equivalent stress of pulp chamber floor decreased by 31. 1%（under 2 mm /45° decreased by 41%）,shear stress of the bonding layer increased by 3. 7%（under2 mm 45° increased by 33. 2%） and equivalent stress of the distal surface of the remaining tooth decreased by 0. 6%（under 2 mm/45° increased by 1. 6%）. For the 5 mm/axial group,equivalent stress of pulp chamber floor decreased by 37%（under 5 mm /45° decreased by 49. 1%）,shear stress sof the bonding layer increased by 13%（under 5 mm /45° increased by 47. 2%） and equivalent stress of the distal surface of the remaining tooth decreased by 7. 3%（under5 mm /45° increased by 10. 5%）. CONCLUSION： When endocrown is used for the restoration of endodontically-treated molar,a thinner cement thickness has a better effect for the long term stabilization of abutment and the endocrown.