Comparative Evaluation of Antimicrobial Efficacy and Cytotoxicity of Ag-ZnO Nanocomposite-Based Oral Rinse Versus Commercial Oral Rinse

Background: The increasing resistance of oral pathogens to conventional antimicrobial agents has prompted the exploration of innovative solutions such as nanocomposite-based formulations. Silver-zinc oxide nanocomposites (Ag-ZnONCs) have demonstrated potent antimicrobial properties, making them promising candidates for oral care products. However, their potential cytotoxic effects necessitate thorough evaluation before clinical application. Materials and Methods: The antimicrobial activity of an Ag-ZnONC-based oral rinse was evaluated using the agar well diffusion method against common oral pathogens, including Staphylococcus aureus, Streptococcus mutans, Lactobacillus sp., Enterococcus faecalis and Candida albicans. The antimicrobial efficacy was tested at concentrations of 25 µg/mL, 50 µg/mL and 100 µg/mL. Cytotoxicity was assessed using a brine shrimp lethality assay by exposing nauplii to varying concentrations of the oral rinses. A commercial herbal oral rinse was used as a comparative control. Results: The Ag-ZnONC-based oral rinse demonstrated superior antimicrobial activity across all tested pathogens. At 100 µg/mL, the Ag-ZnONC rinse achieved inhibition zones of 16 mm for S. mutans, 15 mm for S. aureus, 14 mm for Lactobacillus sp. and 13 mm for E. faecalis and C. albicans. The commercial herbal rinse exhibited lower antimicrobial activity, with inhibition zones ranging from 9 mm to 12 mm. In the cytotoxicity study, both rinses showed a concentration-dependent reduction in brine shrimp survival. At 100 µg/mL, the Ag-ZnONC rinse resulted in 40% survival, while the commercial rinse showed 48% survival, indicating slightly lower cytotoxicity in the commercial formulation. Conclusion: The Ag-ZnONC-based oral rinse demonstrated enhanced antimicrobial efficacy against oral pathogens compared to the commercial herbal rinse. However, its cytotoxic effects at higher concentrations highlight the need for careful dose optimization. Further in vivo studies are recommended to evaluate its safety, stability and long-term clinical effectiveness in oral healthcare applications.