不同修复方式对下颌第一磨牙牙体组织影响的有限元分析

目的探讨下颌第一磨牙经根管治疗后,不同修复方式对牙体组织受力的影响。方法模拟右侧下颌第一磨牙的三维有限元模型,分别以近中--远中（MOD）嵌体,全冠,MOD高嵌体修复,观察不同牙体组织的应力大小及分布。结果高嵌体修复后,牙釉质的最大主应力（εMax）在垂直载荷下较嵌体降低了88.94%,在舌颊向载荷下较嵌体降低了77.92%。垂直载荷下三种修复体的牙本质εMax都出现在根分叉处,全冠修复比嵌体和高嵌体分别高出18.35%和18.16%;而在舌颊向载荷下,全冠修复的牙本质εMax较嵌体和高嵌体分别降低19.63%和17.96%,位置转移至牙根中上1/3处,此时嵌体和高嵌体的牙本质εMax位于髓室底部。结论在生物力学方面,全瓷MOD高嵌体和全瓷冠均可以对牙体组织起到较好的保护作用,其中全冠优于MOD高嵌体。

Finite element analysis of effects on mandibular first molar tissues by fifferent restoration methods

Objective To investigate the effects of different restoration methods for the endodontically treated mandibular first molar using finite element method.Methods The right mandibular first molar was simulated by three-dimension finite element modeling.The restoration methods included mesial-occlusal-distal（MOD） inlay,crown,and MOD onlay.Stress value and distribution in tooth tissue were observed with different restorations.Results With onlay restored,the maximal principal stress（εMax） under vertical loading decreased for 88.94%,compared with the inlay,and for 77.92% under lingual-buccal loading.Under vertical loading,all the dentin εMax appeared on root furcation under vertical loading,and the dentin εMax of crown group was respectively 18.35% and 18.16% higher than the inlay and onlay.Under lingual-buccal loading,the dentin εMax of crown group was respectively 19.63% and 17.96% lower than the inlay and onlay.The dentin maximum stress appeared on the cervical 1/3 of the root in the crown group,and on the bottom of pulp chamber in inlay and onlay group.Conclusion From a biomechanical point of view,porcelain MOD onlay and crown can protect tooth tissue,and the crown is better.