摘要：
BACKGROUND:Prognosis in tooth restoration is affected by different repair methods due to the different biomechanical effects.OBJECTIVE:To analyze three kinds of repair methods and four kinds of repair materials by using three-dimensional finite element analysis.METHODS:Tomographic images of isolated human maxillary first premolars were obtained by Micro CT scanning with a thickness of 0.019 mm.The Mimics output point cloud was used to generate the surface in Geomagic studio and the tooth model was generated respectively.The model was introduced into ABAQUS 6.13 software for Boolean operation,to simulate Inlay,Onlay of the medullary cavity retention type,and Core & Crown repair model.After the grid was divided into four ways of mechanical loading,six-point vertical loading or two-point loading at an angle of 0°,45°,90° with the long tooth shaft was done.The loading force was 75 N at each point.Four repair materials,cobalt-chrome,pure titanium,zirconia,IPS e.MAX,were used in this study.RESULTS AND CONCLUSION:(1) Under the four loading conditions of the same material,the maximum principal stress in the remaining dentin after Inlay restoration was the highest,followed by the Onlay repair and Core&Crown group.(2) Under the four loading conditions via the same approach,the maximum principal stress of the cobalt-chrome alloy in the enamel was the largest,and that of the IPS e.MAX porcelain was the smallest after repair.(3) The stress distribution of the parts was uniform after tooth restoration with the Core & Crown and the Onlay.To conclude,from the stress distribution,the Core&Crown and the Onlay are two ideal methods.Moreover,from the aspects of stress distribution and dentin preservation,Onlay is a more rational and safer way for large-area tooth defects.%背景:对于牙体缺损后治疗,不同修复方式会产生不同的生物力学效果,影响预后.目的:对上颌前磨牙牙体缺损设计3种不同的修复方式和4种不同的修复材料,通过三维有限元方法进行应力分析.方法:以离体人上颌第一前磨牙为研究对象,获取Micro CT扫描数据,建立上颌第一前磨牙缺损修复三维有限元模型,设计嵌体、髓腔固位型高嵌体、桩冠3种修复方式,每种修复方式设计钴铬合金、纯钛、氧化锆、IPS e.MAX全瓷4种修复材料,进行4种方式的力学加载,(牙合)面六点垂直加载或二点与牙长轴呈0°、45°、90°加载,每点加载力大小为75 N,观察模型中各部分的最大主应力的分布情况.结果与结论:①在修复材料相同的情况下,无论何种加载条件,嵌体修复组剩余牙本质的最大主应力最大,高嵌体修复组次之,桩冠修复组最小;②在同种修复方式下,无论何种加载条件,钴铬合金材料修复组牙釉质的最大主应力值最大,IPS e.max全瓷材料修复组最小;③从应力分布来看,桩冠和高嵌体修复组各部分的应力分布均匀;④结果表明,从应力分布来看,桩冠和高嵌体是较为理想的修复方式;从应力分布和保存牙本质的量来看,对于大面积牙体缺损治疗后的修复,高嵌体是更安全合理的修复方式.
