Influence of bioceramic intracanal medication on the bond strength of bioceramic root canal sealer

Abstract To investigate the influence of the remaining volume of a new intracanal medication based on bioceramic compounds on the bond strength (BS) and formation of an adhesive interface between calcium silicate-based and epoxy resin-based root canal sealers. For this purpose, the specimens were distributed according to the intracanal medication (n = 26): Bio-C Temp (BCT) and Ultracal XS (UXS). The roots were scanned in microCT, and after 7 days, the medication was removed. Then a new scan was performed to evaluate the volume of medication remaining. Subsequently, 40 specimens were redistributed into 2 subgroups (n = 10) and filled according to the sealer used: AH Plus (AHP) and Bio-C Sealer (BCS), to assess the bond strength by using the push-out test, and the adhesive interface by confocal laser fluorescence microscopy (CLSM) and scanning electron microscopy (SEM). The t test showed a smaller remainder of BCT (1.77 ± 0.86) compared with UXS (10.47 ± 5.78), irrespective of the root third evaluated. The BS showed that teeth with BCT + BCS had higher bond strength values (3.70 ± 1.22) when compared to the other groups: BCT + AHP (2.15 ± 1.07), UXS + BCS (3.18 ± 1.09) and UXS + AHP (2.11 ± 1.02) (p<0.001). The cervical third had higher BS when compared with the middle and apical thirds (p < 0.001), and higher number of adhesive failures. The adhesive interface in SEM and CLSM images showed better adaptation for the association between BCT + BCS. Intracanal medication and silicate-based endodontic sealer appeared to interact chemically by forming a biomineralizing layer, allowing for an increase in the bond strength and forming an adhesive interface between the materials, with no or less gap formation.

摘要 为探究基于生物陶瓷复合物的新型根管内封药剩余体积对硅酸钙类与环氧树脂类根管封闭剂之间的粘结强度（bond strength, BS）及粘结界面形成的影响，本研究开展相关实验。本研究根据根管内封药类型将样本分为2组（n=26）：Bio-C Temp（BCT）与Ultracal XS（UXS）。利用显微计算机断层扫描（microCT）对牙根进行初始扫描，7天后移除根管内封药，再次扫描以评估剩余封药体积。随后将40个样本重新分为2个亚组（n=10），分别采用AH Plus（AHP）与Bio-C Sealer（BCS）两种根管封闭剂完成根管充填，通过推出试验评估粘结强度，并借助共聚焦激光荧光显微镜（CLSM）与扫描电子显微镜（SEM）观察粘结界面形态。t检验结果显示，无论评估哪一根管区段，BCT的剩余体积（1.77±0.86）均显著低于UXS（10.47±5.78）。粘结强度分析结果表明，BCT+BCS组的粘结强度值（3.70±1.22）显著高于其余各组：BCT+AHP组（2.15±1.07）、UXS+BCS组（3.18±1.09）及UXS+AHP组（2.11±1.02）（p<0.001）。颈段根管的粘结强度显著高于中段与根尖段（p<0.001），且粘结失败发生率更高。SEM与CLSM成像结果显示，BCT与BCS联合使用时的界面适配性更佳。研究表明，根管内封药与硅酸盐类根管封闭剂可通过形成生物矿化层发生化学相互作用，从而提升粘结强度并形成材料间的致密粘结界面，减少甚至消除界面间隙的形成。