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（ex vivo）特定超声器械去除不同硅酸三钙基水硬性水门汀（tricalcium silicate-based hydraulic cements, TCS）的效果，该类材料常作为牙髓再生术（regenerative endodontic procedures）中的盖髓材料。 方法：为构建年轻恒牙模拟模型，将30颗新鲜拔除的上颌切牙根尖截断，随后使用#6号Peeso扩孔钻（Peeso reamers）预备根管。严格遵循美国牙髓病学学会（American Association of Endodontists, AAE）现行牙髓再生操作流程制备离体标本。将环丙沙星、甲硝唑与甘油的混合液置入每颗根管内，放置2周。随后按盖髓材料分为3组：BioDentine、ProRootMTA及RetroMTA（每组n=10）。将密封后的标本置于37℃、100%湿度环境中保存2周，随后采用X射线显微计算机断层扫描（µ-CT）进行扫描。由采用单盲法的同一操作者使用专用去除器械套件取出固化后的硅酸三钙基水硬性水门汀，再次对处理后的标本进行扫描。评估总取出体积、残留体积及操作时长。采用单因素方差分析（One-way ANOVA）结合事后检验（Post-hoc），或克鲁斯卡尔-沃利斯检验（Kruskal-Wallis）结合曼-惠特尼U检验（Mann-Whitney U tests）进行统计学分析，检验水准设为p=0.05。 结果：绝大多数盖髓材料可从根管中被取出（去除率>99%）；但BioDentine、ProRootMTA及RetroMTA的残留体积存在显著统计学差异，分别为0.31±0.0026%、0.05±0.0009%及0.12±0.0009%（p<0.05）。三组的平均操作时长无显著差异。 结论：在本研究局限性范围内可得出结论：当需要取出盖髓材料时，专用超声器械套件对于快凝及慢凝型硅酸三钙基水硬性水门汀均具有良好的去除效果。BioDentine的残留体积相对较高，可能与其较高的黏附特性有关。