Balancing Antibacterial Activity and Mechanical Performance in Dental Resins Using a Cellulose-Derived Crosslinker

Secondary caries driven by biofilm accumulation at restoration surfaces and tooth–restoration interfaces remains a major cause of failure for resin-based restorations, motivating the development of non-leaching, contact-active antibacterial dental resins. However, strengthening antibacterial/anti-adhesion performance by incorporating functional comonomers often compromises mechanical durability, largely due to reduced effective crosslink density and increased susceptibility to hydrolytic degradation. Here, we address this bioactivity–durability trade-off by synergistically incorporating a cellulose-derived methacrylated macromer/crosslinker (ECM) and a fluoride-containing quaternary ammonium methacrylate antibacterial monomer (DMAHDM-F) into a dental resin matrix. ECM serves as a multifunctional macromolecular crosslinking element to reinforce network integrity and enhance effective crosslink density, while DMAHDM-F provides covalently immobilized, non-leaching antibacterial activity via quaternary ammonium functionality. The optimized formulation (ACDR-5) combines high flexural strength and modulus with pronounced antibacterial efficacy against Streptococcus mutans . Moreover, ACDR-5 maintains > 90% viability of human gingival fibroblasts, indicating favorable cytocompatibility. This dual-functional, network-reinforced design provides a straightforward strategy to reconcile sustained antibacterial performance with mechanical durability in light-cured dental resins.