Effect of antioxidants on dentinal tubular penetration of root canal sealers in sodium hypochlorite treated root canal dentin: a systematic review

Background The long-term success of root canal treatment depends on the formation of an effective three-dimensional seal, which is strongly influenced by the ability of endodontic sealers to penetrate dentinal tubules and adapt closely to the root canal walls. Sodium hypochlorite (NaOCl), the most commonly used endodontic irrigant, produces oxidative alterations in dentin, including collagen degradation, reduced surface wettability, and residual free radical formation, which collectively compromise sealer penetration and interfacial integrity. The use of antioxidant agents has been used as a strategy to reverse these adverse effects and restore dentin surface properties. Objective This systematic review aimed to assess the influence of various antioxidant agents on dentinal tubular penetration and interfacial adaptation of root canal sealers following NaOCl irrigation. Methods A comprehensive electronic search of PubMed, Scopus, Web of Science, and Google Scholar was performed up to November 2025. In vitro studies evaluating NaOCl-treated dentin followed by antioxidant application and reporting sealer penetration or adaptation outcomes using confocal laser scanning microscopy (CLSM) or scanning electron microscopy (SEM) were included. Methodological quality and risk of bias were evaluated using a modified QUIN assessment tool. Results From 216 initially identified records, four studies fulfilled the eligibility criteria. The antioxidants investigated included ascorbic acid, tannic acid, gallic acid, ellagic acid, sodium thiosulfate, and glutathione. All antioxidant-treated groups demonstrated greater dentinal tubular penetration and increased interfacial adaptation compared with NaOCl-only controls. Polyphenolic antioxidants, particularly gallic acid and ellagic acid, produced the greatest enhancement in penetration depth. Sodium thiosulfate significantly reduced interfacial gaps and voids, while glutathione improved sealer penetration in both resin-based and bioceramic sealers and was associated with increased bond strength. Conclusion The available in vitro evidence indicates that antioxidant agents effectively mitigate NaOCl-induced oxidative changes in dentin, leading to improved sealer penetration and adaptation. Incorporating antioxidants as a final irrigant step may enhance obturation quality and potentially improve sealer peneteration; however, well-designed clinical studies are required to confirm these findings. Systematic Review Registration https://doi.org/10.17605/OSF.IO/PBRQA.