不同开髓方法下上中切牙贴面修复的三维有限元分析

Three-Dimensional Finite Element Analysis of Upper and Middle Incisor Veneer Restoration Under Different Pulp Opening Methods

目的应用三维有限元分析法分析上颌中切牙在不同开髓方法下贴面修复对牙体组织应力分布的影响。方法建构上颌中切牙进行三维实体模型,依据开髓方式的与贴面修复方式的不同分别建立四组实验模型,A组为传统开髓对接型瓷贴面,B组为传统开髓包饶型瓷贴面,C组为微创开髓对接型瓷贴面,D组为微创开髓包饶型瓷贴面。加载力为静态力,施力方向和牙体长轴相交呈45°,设定载荷大小为100N,于腭侧中1/3和切1/3相交处施力,分析指标是von Mises应力、最大主应力。结果(1)应力峰值:通过von Mises应力和最大主应力的数据呈现,传统开髓对接型(A组)呈现出最高的应力峰值,微创开髓对接型(C组)呈现出最低的应力峰值。(2)应力分布:相比A组,C组的应力分布情况优于A组,应力向根尖更广区域分散;相比B组,D组的应力分布情况优于与B组,应力向根尖更广区域分散;对比最大主应力与von Mises应力的应力峰值数据,A组峰值数值高于B组;D组峰值数值稍高于C组;A组和B组在应力分布情况上差异不明显;C组和D组在应力分布情况上差异不明显。结论从生物力学角度考虑上颌中切牙开髓建议使用微创方式;传统开髓后建议选取包饶型贴面;微创开髓后两终贴面均可选择。

Objective To analyze the effect of veneer restoration on the stress distribution of maxillary central incisor with different endodontics access methods by three-dimensional finite element method.Methods A three-dimensional corporeal model of maxillary central incisor was builded.Four groups of experimental models were established according to the discrepant methods of endodontics and veneer repair.Group A was the traditional pulp open butt porcelain veneer,group B was the traditional pulp open butt porcelain veneer,group C was the minimally invasive pulp open butt porcelain veneer,and group D was the minimally invasive pulp open butt porcelain veneer.The loading force was static force,and the direction of force application intersects with the tooth axis at a 45°.The load was set as 100N,and the force was applied at the intersection of the middle 1/3 of the palatal side and the cut 1/3.The analysis indexes were von Mises stress and maximum main stress.Results(1)the maximum value stress of traditional open type pulp docking(group A)von Mises stress and the maximum main stress assumes the highest stress peak,minimally invasive open type pulp docking(group C)von Mises stress and maximum principal stress presents the minimum stress peak value.(2)Distribution of stress:match group C against group A,the stress distribution of group C is better than group A,and the tress disperses towards a wider area in the tooth root.Match group D against group B,the group D’s stress distribution was better than that of group B,and the stress dispersed to a wider area in the tooth root.The maximum value stress of group A in the maximum main stress and von Mises stress were more than those of group B.The maximum main stress and von Mises maximum value stress of group D were slightly higher than those of group C.The difference of stress distribution between group A and group B is not obvious.The difference of stress distribution between group C and group D is not obvious.Conclusion It is recommended to use minimally invasive methods to open the tooth canal of maxillary central incisor teeth.After traditional pulp opening,it is recommended to choose the bag type veneer;Both final veneers can be selected after minimally invasive pulp opening.