Objective: The present study evaluated the cell viability and antimicrobial effects of orthodontic bands coated with silver and zinc oxide nanoparticles.
Methods: In this experimental study, thirty orthodontic bands were divided into three groups (n=10) of control (uncoated band), silver (Ag) coated band and zinc oxide (ZnO) coated band. The electrostatic spray-assisted vapor deposition method was used to coat silver (Ag) and zinc oxide (ZnO) nanoparticles on orthodontic bands. The biofilm inhibition test assessed the antimicrobial effectiveness of nano-Ag and nano-ZnO against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. Biocompatibility tests were carried out using an MTT assay. A One-way ANOVA with a Post-hoc test was used for the comparison between groups.
Results: The reduction in the number of L. acidophilus, C. albicans, and S. mutans colonies around nano-Ag coated bands was significantly higher than around nano-ZnO coated bands (P= 0.015, 0.003, and 0.005, respectively). Compared to the control group, Ag showed a reduction of all microorganisms' ability to replicate at least 2 log10 steps; but ZnO, except for S. mutants, reduced the other two microorganisms to less than 2 log10 steps. The lowest cell viability mean was observed in nano-Ag coated bands, but the difference between the groups was insignificant (P>0.05).
Conclusion: Coating orthodontic bands with ZnO and Ag nanoparticles induced antimicrobial properties against oral pathogens. Among these nanoparticles, the Ag group showed the best antimicrobial activity and the ZnO group showed the highest biocompatibility.

Keywords: Biocompatibility, SEM, Microbiology, Biomaterial science