Evaluation of ex vivo removal effectiveness of tricalcium silicate-based hydraulic cements used in ‘regenerative endodontic procedures’ as capping material: a Micro-computed tomography analysis.

Introduction: To evaluate ex vivo the efficiency of specific ultrasonics for the removal of different tricalcium silicate-based hydraulic cements (TCS) as capping material for regenerative endodontic procedures.
Methods: To prepare the immature teeth simulations, the apices freshly extracted 30 maxillary incisors were cut, then root canals were shaped up to #6 Peeso reamers. The current regeneration steps of the American Association of Endodontists(AAE) were followed for the ex vivo specimen preparations. The mixture of Ciprofloxacin and Metronidazole with glycerine was placed in each canal for 2 weeks. Then capping material groups were created: BioDentine, ProRootMTA, and RetroMTA(n=10). The sealed specimens were stored for 2 weeks at 37ºC at 100% humidity then were scanned using X-ray µ-computed tomography(µ-CT). The set TCSs were retrieved using a specific removal kit by a single operator as blind. The post-treated specimens were scanned again. The total and residual volumes and the durations were evaluated. One-way ANOVA followed by Post-hoc or Kruskal-Wallis followed by Mann-Whitney U tests were performed(p=0.05).
Results: The capping materials were mostly removed from the root canals(>99%), whereas, significant differences were revealed among the residual volume of BioDentine, ProRootMTA, and RetroMTA as 0.31±0.0026%, 0.05±0.0009%, and 0.12±0.0009%, respectively(p<0.05). There was no significant difference among the mean durations.
Conclusion: Within the limitations, it can be concluded that when the capping material is essential to remove, the specific ultrasonic kit seems to be an efficient tool for the slow-setting or fast-setting TCSs. Relatively high residual volume of BioDentine might be ascribed to its high adhesive property.

引言：本研究旨在离体评估特定超声设备用于清除不同硅酸三钙基水硬性水门汀（tricalcium silicate-based hydraulic cements, TCS）作为牙髓再生术盖髓材料的清除效率。
材料与方法：为构建年轻恒牙模拟模型，选取30颗新鲜拔除的上颌切牙，截取根尖段后将根管预备至#6号Peeso扩孔钻。离体样本制备严格遵循美国牙髓病学协会（American Association of Endodontists, AAE）现行牙髓再生操作流程。将环丙沙星、甲硝唑联合甘油制剂注入每根根管，留置2周。随后设置盖髓材料实验组：BioDentine、ProRootMTA及RetroMTA，每组10例样本（n=10）。将密封后的样本置于37℃、100%湿度环境中储存2周，随后采用X射线显微计算机断层扫描（µ-computed tomography, µ-CT）进行扫描。由1名采用盲法设计的操作者使用专用清除试剂盒完成固化TCS的清除操作。处理后的样本再次进行扫描，评估总清除体积、残留体积及清除时长。采用单因素方差分析结合事后检验，或Kruskal-Wallis检验结合Mann-Whitney U检验进行统计学分析，检验水准设定为p=0.05。
结果：三种盖髓材料的根管清除率均超过99%，但BioDentine、ProRootMTA及RetroMTA的残留体积分别为0.31±0.0026%、0.05±0.0009%及0.12±0.0009%，组间差异具有统计学意义（p<0.05）。各组的平均清除时长无显著差异。
结论：本研究存在一定局限性，综上可知，当需要清除盖髓材料时，专用超声试剂盒可有效清除速凝或缓凝型TCS。BioDentine残留体积相对较高，可能与其较强的黏附性有关。