纤维桩核修复3种上切牙牙冠缺损类型的有限元应力对比*

挑选1颗牙体完好无损，解剖值符合国内牙体解剖平均数据的成人离体上中切牙。使用牙科专用锥形束CT扫描，图像处理并根据牙冠和牙本质肩领的不同缺损量逆向建立3种不同缺损类型的牙体-纤维桩核-全瓷冠的三维有限元模型。模型1：牙冠横行缺损，存在2 mm的完整牙本质肩领；模型2：牙冠近远中斜行缺损，牙本质肩领部分缺失；模型3：牙冠横行缺损，牙本质肩领完全缺失。用ABAQUS软件进行三维有限元分析，对比加载后3个模型的应力分布状态。牙本质肩领不完整的牙冠近远中向斜行缺损时，与牙本质肩领完整牙齿的应力分布情况接近，但粘接剂和纤维桩上的应力峰值明显低于无牙本质肩领的牙齿模型。提示纤维树脂桩核修复牙本质肩领完整的牙冠横行缺损效果最佳；牙本质肩领部分缺失的牙冠近远中斜行缺损仍可以使用纤维树脂桩核修复体；纤维桩核修复无牙本质肩领的牙冠横行缺损时，脱落、折断的可能性增大。

Fiber post-core restoration for three types of incisor crown defects: Finite element analysis of stress

Selection of an intact tooth, anatomical value should be consistent with the anatomy data of Chinese teeth on adult incisor in vitro. Dental cone-beam CT scanning was used for image processing to reversely construct three-dimensional finite element models of three different types of dental defects-fiber post and core-all-ceramic crowns in accordance with crown and dentin shoulder from the volume of the different defect. Model 1 of crown transverse defects, with the integrity of the dentin 2 mm ferrule; Model 2 of crown mesial-distal oblique defects, missing parts of dentin ferrule; Model 3 of crown transverse defects, completely missing ferrule. ABAQUS was used for three-dimensional finite element analysis to compare the three models after loading the stress. The stress distribution of teeth with incomplete ferrule and complete 2 mm ferrule were similar and significantly lower than that without dentin shoulder collar teeth model. Fiber resin post and core for restoration of complete 2 mm ferrule displays the best effect; it can also be used to restore the incompletely defect ferrule from near distal oblique defect; However, it is not favorable to restore the defects without ferrule, which increases possibility of defluxion and fracture.