纯钛桩和纤维桩修复上颌中切牙残根后桩的应力分析

摘要

目的:通过建立纯钛桩核冠及纤维桩核冠修复上颌中切牙残根的三维有限元模型,分析正常咬合情况下两种桩核系统修复上颌中切牙残根后桩的应力分布.方法:使用Micro-CT断层扫描技术以21μm的最小层间距扫描上颌中切牙切缘至牙根,获得横断面数据,利用图像分析软件及逆向工程软件构建上颌中切牙三维有限元模型,Ansys软件进行模拟加载,利用有限元应力分析法比较咬合力作用下应力在两种桩表面的分布.结果:纤维桩的最大主应力、剪切应力、等效应力峰值均比纯钛桩减少90%左右,纯钛桩核修复组桩各区域应力值均大于纤维桩核修复组.纯钛桩应力集中区域出现在根中1/3唇侧,达到33.59M Pa,纤维桩相同区域的应力值仅有0.6M Pa.结论:对于具有正常根管形态及牙本质肩领的上颌中切牙残根,纤维桩树脂桩核冠能更好地避免桩的应力集中,从而有效降低桩折及牙根折裂的概率,可为上颌中切牙残根的修复设计提供参考.%Objective:Models of maxillary central incisor residual root restored with titanium post-core crown and fiber post-core crown were built to analyze the stress distribution on the posts by finite element method .Meth-ods :The sample was scanned by Inveon Micro-CT technology from incised margin to root apical at a 21μm interval to obtain transverse sectional images .The three-dimensional finite element model was created by rebuilding the mor-phology of maxillary central incisor with inveon research workplace ,combined Mimics ,geom-agic and catia soft-ware .The model was meshed and loaded to analyze the stress distribution on the post by finite element method .Re-sults :The maximum stress ,shearing stress and equivalent stress on the fiber post were 90% less than that on the titanium post in the experiment .All parts of the titanium post had higher stress than the fiber post .Furthermore , the stress concentration mainly occurred on the labial surface of the middle 1/3 of root ,which reached 33 .59 MPa , while the stress on the area of fiber post was merely 0 .6 MPa .Conclusion :The finite element analysis indicated that the fiber post-core crown is better than titanium post-core crown to avoid stress-concentration and post or root frac-ture on the natural residual root of central incisors with dentin ferrule .