NIR-Activated Antibacterial Hydrogel against E. faecalis for Enhanced Root Canal Disinfection

Persistent microbial infections within the root canal system remain a major challenge contributing to endodontic treatment failure. The limited antibacterial efficacy and insufficient biofilm-disrupting capability of current intracanal medicaments highlight the need for innovative therapeutic approaches. In this study, we developed a quaternized chitosan/oxidized dextran (QCS/OD) hydrogel incorporated with polydopamine nanoparticles (PDA NPs), termed QDP hydrogel, to achieve enhanced antibacterial activity through NIR-triggered photothermal activation. The physicochemical properties, injectability, removability, and antibacterial performance of QDP hydrogels were systematically evaluated, which exhibited favorable injectability and could be readily removed from root canals for the following intracanal obturation. Moreover, QDP hydrogels demonstrated potent antibacterial activity against planktonic E. faecalis , mature E. faecalis biofilms, and biofilms within ex vivo infected root canal models. Importantly, the NIR-induced photothermal effect effectively eliminated bacterial biofilms without compromising the cytocompatibility of periodontal ligament stem cells (PDLSCs). Collectively, these findings indicate that the QDP hydrogel provides a novel intracanal therapeutic platform for potential endodontic applications.