Evaluation of Cytotoxicity and Embryotoxicity of Ocimum tenuiflorum-Ocimum gratissimum Mediated Silver Nanoparticle-Based Dental Varnish: A Comparative Study with Commercial Varnish

Background: Silver nanoparticles (AgNPs) are widely recognized for their potent antimicrobial properties, making them promising candidates for dental applications. However, concerns regarding their potential cytotoxicity and embryotoxicity remain significant. This study evaluates the safety profile of a green-synthesized AgNPs-based dental varnish using Ocimum tenuiflorum and Ocimum gratissimum extracts as reducing and stabilizing agents. The study aims to compare its toxicity profile with a commercial dental varnish to assess its potential as a safer alternative in dental care. Methods: AgNPs were synthesized using Ocimum tenuiflorum and Ocimum gratissimum extracts, confirmed by visual color change and UV-Visible spectroscopy. Zebrafish embryos were selected as a model to evaluate toxicity. Embryos were exposed to different concentrations of the AgNPs-based dental varnish (5, 10, 20, 40 and 80 µg/mL), with their viability, hatching rates and morphological changes recorded. The commercial dental varnish was tested under identical conditions to serve as a comparison. Results: The AgNPs-based varnish displayed concentration-dependent toxicity. At lower concentrations (5 and 10 µg/mL), 100% viability and 100% hatching rates were observed, similar to the control. At 40 µg/mL, slight toxicity was evident, with viability decreasing to 85% and hatching rates reducing to 80%. At 80 µg/mL, the AgNPs varnish showed reduced viability (60%) and hatching rates (60%). In comparison, the commercial varnish exhibited greater toxicity, with only 50% hatching rates observed at 80 µg/mL and higher instances of morphological abnormalities in zebrafish embryos. Conclusion: The green-synthesized AgNPs-based dental varnish demonstrated reduced toxicity compared to the commercial dental varnish at higher concentrations. The antioxidant properties of phytochemicals present in Ocimum extracts, such as eugenol and rosmarinic acid, may have contributed to stabilizing the nanoparticles, thus minimizing oxidative stress. These findings suggest that the AgNPs-based varnish holds promise as a safer and eco-friendly dental care alternative. Further in vivo studies are recommended to assess its long-term safety and clinical efficacy.