In vivo antimicrobial potential of orthodontic bands coated with green-synthesized zinc oxide, titanium oxide, and their nanocomposites

Abstract

Background. Orthodontic bands are prone to biofilm accumulation, leading to dental plaque formation and increased risk of caries. Incorporating antimicrobial coatings on these bands can help reduce microbial colonization. This study investigates the in-vivo antimicrobial efficacy and biocompatibility of orthodontic bands coated with green-synthe-sized zinc oxide (ZnO), titanium dioxide (TiO₂) nanoparticles, and their nanocomposites. Materials and methods. ZnO and TiO₂ nanoparticles were synthesized using eco-friendly green synthesis methods and characterized for size and stability. Orthodontic bands were coated with individual nanoparticles and nanocompos-ites. The coated bands were placed intraorally in animal models. Microbial colonization by Streptococcus mutans and Streptococcus mitis was assessed on days 1, 7, 14, and 30. Antifungal activity and systemic toxicity were also evaluated through microbiological and histopathological analyses. Results. ZnO-coated bands exhibited the greatest antimicrobial efficacy, demonstrating an 84-89% reduction in S. mutans CFU by Day 30 compared with uncoated controls (p < 0.001). The ZnO–TiO₂ nanocomposite coatings also showed strong activity, achieving a 72–78% reduction in both S. mutans and S. mitis (p < 0.01). All coating groups main-tained consistent antimicrobial effects throughout the 30-day evaluation period, and no fungal growth was observed beyond day 1, confirming early and sustained antifungal action. Histological examination of major organs – including the liver, kidneys, and spleen – revealed normal architecture with no inflammatory or structural alterations, confirming good biocompatibility and the absence of systemic toxicity. Conclusion. Green-synthesized nanoparticle coatings, particularly ZnO, are effective in reducing microbial colonization on orthodontic bands without inducing systemic toxicity. These findings support the potential clinical application of eco-friendly antimicrobial coatings in orthodontics and warrant further investigation through long-term studies and clinical trials.