不同固位形和树脂对前牙断冠再接应力影响的有限元分析

Effect of different retention forms and resins on reattachment stress of anterior teeth with fractured crown based on finite element analysis

背景:影响断冠再接术效果的因素有断冠的保存、粘接剂树脂和固位形等,目前还没有就固位形和树脂弹性模量对断冠再接应力影响的综合研究。目的:应用三维有限元法分析不同固位形和树脂对前牙断冠再接应力的影响。方法:基于CT扫描数据,采用Mimics和Geomagic软件生成前牙三维数字模型,利用SolidWorks软件建立直接再接、牙本质内沟、唇面覆盖和内部凹槽4种断冠再接固位形,每种固位形分别使用5种弹性模量的树脂生成20个ANSYS有限元模型。通过材料力学分析,选取粘接剂剪力、剪应力和树脂等效应力、第一主应力作为评估指标。结果与结论:①直接再接和唇面覆盖固位形的剪应力分布情况相近,剪应力峰值均分布在牙本质和牙釉质交界处,且集中在左右两侧;牙本质内沟固位形的剪应力峰值分布在牙本质沟与断面交界的左右两侧;内部凹槽固位形的剪应力峰值分布在凹槽与断面交界的左右两侧;②各种固位形的树脂Von Mises等效应力峰值均分布在舌侧的中间部位;唇面覆盖固位形的唇面填充树脂应力较小,距离断面越远应力越小;③各种固位形的树脂第一主应力峰值均在牙本质和牙釉质分界处,此处树脂承受较大的拉应力,在舌侧树脂承受较大的压应力;④固位形对粘接剂剪力和剪应力均具有较大影响,弹性模量仅对粘接剂剪应力有影响;固位形对树脂Von Mises应力峰值和第一主应力峰值均具有较大影响,弹性模量仅对树脂第一主应力有影响;⑤牙本质内沟固位形各项评估指标均最优,因此临床上建议采用牙本质内沟固位形。

BACKGROUND:The factors that affect the effect of fractured crown reattachment include the preservation of fractured crown,adhesive resin and retention form,etc.There is no comprehensive study on the effect of retention form and elastic modulus of resin on fractured crown reattachment stress.OBJECTIVE:To study the effect of different retention forms and resins on the central incisor reattachment by three-dimensional finite element analysis.METHODS:Based on CT scan data,Mimics software and Geomagic software were used to generate 3D digital model of anterior teeth.SolidWorks software was used to establish four types of retention forms,including direct reattachment,internal dentin groove,overcontour and internal groove.Five types of resins were used to generate 20 ANSYS finite element models.The adhesive shear force,shear stress and resin equivalent stress,and the first principal stress were selected as evaluation indicators through material mechanics analysis.RESULTS AND CONCLUSION:(1)The shear stress distributions of the direct reconnection and the lip-covering retention were similar,and the shear stress peaks were distributed at the junction of dentin and enamel,and concentrated on the left and right sides.The shear stress peak distribution of the dentin internal groove retention was on the left and right sides of the junction between the dentin groove and the section.The shear stress peaks of the internal groove retention form were distributed on the left and right sides of the junction between the groove and the section.(2)The equivalent stress peaks of resin Von Mises of various retention forms were distributed equally in the middle part of the lingual side.The lip surface covering the retention form was filled with resin with less stress,and the farther away from the cross-section,the less stress.(3)The first principal stress peaks of various retention forms were at the boundary of the dentin and enamel where the resin bore greater tensile stress here,and the resin bore greater compressive stress on the lingual side.(4)The retention form had a great influence on the shear force and shear stress of the adhesive,and the elastic modulus only affected the shear stress of adhesive.The retention form had a great influence on the Von Mises stress peak and the first principal stress peak of the resin,and the elastic modulus only affects the first principal stress of the resin.(5)The evaluation indexes of the dentin internal groove retention form are the best,so it is recommended to use the dentin internal groove retention form in clinical practice.