不同根管预备方法对根管壁应力分布的影响

目的:研究不同根管预备方法对根管应力大小和分布的影响,从生物力学角度探讨不同根管预备方法对根管抗性的影响。方法:选取30颗离体下颌单根管第一前磨牙,随机分成三组,每组10个牙:G1组(标准法)用旋转镍钛器械Mtwo预备;G2组(冠向下法)用旋转镍钛器械Protaper预备;G3组(逐步后退法)用不锈钢K锉预备。各组按相应方法预备后,进行根管充填,复合树脂修复。运用技术和abqus有限元分析软件结合,分别建立各组实验牙齿三维有限元模型,采用中央垂直加载,计算三种不同根管预备方法预备后根管壁的应力大小及分布状况。结果:各实验组预备后剩余根管壁牙本质上平均应力水平略有差异,G1组与G3组、G2组与G3组间差异具有统计学意义(P<0.05),G1组与G2组间差异无统计学意义(P>0.05)。结论:各实验组平均Von mises应力峰值均远小于牙本质的极限压缩强度,这三种常用的根管预备方法都是安全可行的。镍钛Protaper和Mtwo使根管应力分布更加均衡,明显减小了应力集中,推荐使用Protaper和Mtwo来进行根管预备来预防牙根纵裂的发生。

The effect on the stress distribution of root canal wall by different root canal preparation methods.

Objective： The main purpose of this study was to analyze the effect of different canal preparation techniques on the root canal stress values, and to explore the affect of different canal preparation techniques on the resistance of the root from a biomechanical viewpoint. Method： A total of 30 exacted human dental mandibular single canal premolar were randomly allocated into three groups （n=10）： Groupl, Standardized system using rotary Ni-Ti Mtwo instrument; Group2, Crown-down technique using rotary Ni-Ti Protaper instrument： Group3, step-back technique using conventional stainless steelK-files.Using technologies and Abaqus 6.10 software,they established finite element models of each group and tested root canal stress under central vertical loading conditions. Result： In all experimental groups,the average stress level of the remaining dentin after root canal preparation and filling were slightly different. There were statistically significant differences in G1,G3 andG2, G3 （P 〈0.05）,bat there were no statistically significant differences between G1 and G2. Conclusion：In each experimental group average Von mises stress peak were much less than the limits of dentin compressive strength. These three common root canal preparation were safe and feasible. Protaper and Mtwo nickel titaniums maked the distribution of root canal stress more balanced, significantly reducing the stress concentration.So we recommended the use of Protaper and Mtwo nickel titaniums for root canal oreoaration to orevent the occurrence of vertical root fracture.