Physicochemical and antibacterial properties of composite resin incorporating glycidyl methacrylate-chitosan derivative

Abstract This study synthesized a polymerizable chitosan derivative, glycidyl methacrylate-chitosan (GMA-Chitosan), which was covalently incorporated into a resin matrix to overcome the limitations of physical blending. Experimental groups containing 1 wt%, 3wt%, 5 wt% and 10 wt% GMA-Chitosan were compared with an unmodified flowable composite resin. Microhardness, water sorption, and antibacterial effects were assessed using Vickers testing, immersion tests, contact inhibition assays, confocal microscopy, and scanning electron microscopy. The synthesized GMA-Chitosan exhibited reduced crystallinity and thermal stability. Resins with 3 wt% and 5 wt% GMA-Chitosan maintained microhardness similar to the control (p > 0.05) , while the 10 wt% group exhibited a significant decrease (p < 0.05). Water sorption increased significantly at higher concentrations (p < 0.05) but remained within acceptable limits for dental nanocomposites. Antibacterial tests demonstrated a significant, dose-dependent reduction in Streptococcus mutans adhesion for resins containing 3 wt%, 5 wt%, and 10 wt% GMA-Chitosan (p < 0.05). Microscopic analysis confirmed bactericidal effects and bacterial membrane disruption. Notably, the antibacterial efficacy persisted after 30 days of artificial aging. The findings indicate that formulations with 3 wt% and 5 wt% GMA-Chitosan achieve an optimal balance between maintaining acceptable mechanical properties and exhibiting stable antibacterial activity, suggesting their potential for clinical applications in dental restorations where both material integrity and antimicrobial effects are desired.