Comparison of different retreatment techniques and root canal sealers: a scanning electron microscopic study

The aim of this study was to evaluate the effectiveness of two retreatment techniques, in terms of the operating time and scanning electron microscopy (SEM) results, in removing three different root canal sealers from root canals that were previously filled with gutta-percha. Sixty extracted single-rooted human premolars were divided into three groups and filled with iRoot SP, MM Seal, and AH Plus sealers, along with gutta-percha, through a lateral compaction technique. Root canal fillings of the samples were removed by ESI ultrasonic tips or R-Endo files. The time to reach the working length was recorded. Longitudinally sectioned samples were examined under SEM magnification. Each picture was evaluated in terms of the residual debris. Data were statistically analyzed with the Kruskall-Wallis test. No statistically significant differences were found in terms of operating time (p>0.05). Significant differences in the number of debris-free dentinal tubules were found among the root canal thirds, but this finding was not influenced by the experimental group (p < 0.05). Resin sealer tags were observed inside the dentinal tubules in the MM Seal group. Under the conditions of this study, it may be established that there was no difference among the sealers and retreatment techniques.

本研究旨在评估两种再治疗技术在操作时间与扫描电子显微镜（scanning electron microscopy，SEM）检测结果层面的有效性，探究其从既往以牙胶尖充填的根管内去除三种不同根管封闭剂（root canal sealers）的效果。本研究选取60颗拔除的单根人前磨牙，分为三组，采用侧向加压充填技术，分别以iRoot SP、MM Seal及AH Plus封闭剂联合牙胶尖完成根管充填。随后采用ESI超声工作尖或R-Endo锉去除各组样本的根管充填物，并记录其到达根管工作长度所需的时间。将样本制备为纵向切片后，于SEM下放大观察，并针对每张图像的残留碎屑情况进行评估。采用克拉斯卡尔-沃利斯检验对所得数据进行统计学分析。结果显示，操作时间方面未发现具有统计学意义的差异（p>0.05）；根管各区段的无碎屑牙本质小管数量存在显著差异，但该差异不受实验组别的影响（p<0.05）；MM Seal组的牙本质小管内可见树脂封闭剂突。在本研究的实验条件下，可认为不同根管封闭剂及再治疗技术之间并无显著差异。