桩核对牙冠完整的上颌第一前磨牙的应力影响

目的:采用有限元法比较不同桩核或有无桩核修复牙冠完整的上颌第一前磨牙时牙体组织的应力情况.方法:采用New Tom锥形束CT扫描获取数据,建立四种三维有限元模型,加载偏舌侧45°角的150N力.结果:在桩尖区钴铬合金桩核修复时应力集中,VoMises应力峰值39.3MPa比对照组14.2MPa增加176.8％；纤维桩核修复时应力均匀,VonMises应力峰值16.7MPa比对照组14.2MPa增加17.6％,钴铬合金桩核修复最大主应力峰值13.4MPa是纤维桩核修复9.3MPa的1.44倍；用树脂材料直接充填时(无桩核)应力与对照组基本一致.结论:与钴铬合金桩核相比,纤维桩核更适合上颌第一前磨牙修复；在牙冠部有足够牙体组织时,直接由树脂材料充填开髓洞型后行全冠修复是可行的.

The influence of post and core on the stress of maxillary first premolar with complete dental crown

Objective： To investigate the stress condition in dentine of maxillary first premolar with complete detal crowns under post crown or without post crown through three-dimensional finite element. Method： Four three-dimensional finite element models were constructed by the data of New Tom tapered beam computed tomography （CT）. Load was ap- plied with the force of 150N which was inclined lingual direction 45~ angle. Result： The stress concentrated area of tooth restrored with cast C0-Cr alloy post and core was observed in the tip of the post, while the area of tooth restored with fiber post and resin core was not obvious. There was no difference of stress between fiber post-resin core group and control group. Conclusion： Compared with cast Co-Cr alloy post-and-core, fiber post and resin core was more suitable for restoring maxillary first premolar. As for the tooth with sufficient coronal tooth substance, post was not absolutely necessary and resin filling followed by crown restoration might be one of the alternative restorations.