微焦点CT技术评价镍钛再治疗器械去根管内充填材料的效果

目的：利用微焦点CT技术定量比较两种镍钛再治疗器械与手用不锈钢器械去根管内充填材料的效果。方法：30颗离体前牙经逐步后退法预备根管后行冷侧方加压充填,随机分为3组,分别使用K锉、ProTaper D和Mtwo R去根管内充填物。再治疗前后分别对实验牙进行微焦点CT扫描,CT图像处理软件处理图像,计算根管内中1/3段和尖1/3段充填材料体积并比较其残留充填材料体积百分数。结果：在根管中1/3段,Mtwo R组根管残留充填材料体积百分数均数最小,与其他两组根管中1/3段间存在显著性差异（P〈0.05）。结论：在本实验条件下,K锉、Mtwo R和ProTaper D这3种器械在去根管内充填材料时,Mtwo R组清理效果最好。

Efficiency Evaluation of Ni-- Ti Retreatment Instrument for Root Filling Material Removal by Micro--CT

Objective： To evaluate the efficacy of two nickel--titanium retreatment systems and k--file for root filling material removal using micro--CT. Methods： Thirty anterior teeth with single straight root canal were pre- pared with step ,-- back technique, and obturated with gutta--percha cone using cold lateral compaction technique. The teeth were randomly divided into three groups. Then the root filling material was removed with K--file, Mtwo retreatment instrument or ProTaper Universal retreatment instrument. Roots were scanned with micro--CT before and after the removal procedure. The volume of filling material inside middle third and apical third of the root canal measurements were carried out by using specialized CT software. Percentage of the remaining filling material volume was assessed. Results： At middle third of the canals, the average percentage of the volume of remaining filling material in group Mtwo retreatment instrument was significantly less than that in other groups（P〈0.05）. Conclusion： Under the condition of this study, the efficacy of Mtwo retreatment instrument for root filling material removal may be greater than other two instruments.