Transition Metal Doped Zinc Oxide Nanoparticles Ameliorates Antibacterial Potential of Dental Resin Composite in a Closed System In-vitro Biofilm Model

Doped Zinc oxide (ZnO) Nanoparticles (NPs) have been widely studied in a variety of diagnostic and therapeutic applications. However, transition metal doped ZnO NPs have been rarely explored as an antibacterial agent in dental restorative materials. This study aimed to synthesize and characterize ZnO NPs doped with transition metals i.e. Copper (Cu) and Silver (Ag) and enhancement of resin composite with these NPs to evaluate their antibacterial and mechanical properties. Cu/ZnO NPs and Ag/ZnO NPs of 23.6 and 20.5 nm respectively, were successfully prepared by coprecipitation method, and confirmed by UV-vis spectroscopy, Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDX), Fourier transform infrared (FTIR). After successful doping, varying concentrations of bare and doped NPs were added into the composite. The composite disks were then exposed to S.mutans, in a closed system in vitro biofilm model followed by assessment of Colony-forming units (CFU/mL) to realize the antibacterial activity. To analyze mechanical properties, compressive strength analysis was carried out using a universal testing machine. The biocompatibility was evaluated by performing a hemocompatibility test. The composites with both Cu/ZnO and Ag/ZnO NPs exhibited enhanced antibacterial activity compared to composites with bare ZnO NPs at all concentrations. However, at higher concentrations of doped ZnO NPs, the aesthetics of the composites were compromised. In summary, this study demonstrated that transition metal doped ZnO NPs, specifically Ag/ZnO at 1% concentration can be used as antibacterial agent in dental restorative materials without affecting their biocompatibility and mechanical strength.