In vitro evaluation of the antimicrobial effects of orthodontic bands coated with silver or zinc oxide nanoparticles

Abstract

Background

Orthodontic bands are widely used in clinical orthodontics; however, they often create niches for bacterial accumulation, leading to enamel demineralization and gingival inflammation. To counteract microbial growth, silver and zinc oxide nanoparticles (AgNPs and ZnONPs) have been explored for their antimicrobial properties. This in vitro study aims to evaluate and compare the antimicrobial efficacy of orthodontic bands coated with AgNPs and ZnONPs against key oral pathogens.

Materials and Methods

Orthodontic bands were divided into three groups: Group A: Uncoated control bands, Group B: Bands coated with silver nanoparticles (AgNPs), Group C: Bands coated with zinc oxide nanoparticles (ZnONPs). The nanoparticles were synthesized and applied using the dip-coating method. Bands were then exposed to Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans in nutrient broth. The antimicrobial activity was evaluated using the disk diffusion method and zone of inhibition (ZOI) was measured in millimeters (mm). In addition, colony-forming unit (CFU) reduction was analyzed after 24 and 48 hours of incubation.

Results

Zone of Inhibition: Group B (AgNPs): 15.2 ± 1.3 mm (against S. mutans), Group C (ZnONPs): 12.4 ± 1.1 mm (against S. mutans), Minimal zones for the control group (Group A). Colony-Forming Unit (CFU) Reduction: Group B: 85% reduction after 24 hours and 92% after 48 hours. Group C: 78% reduction after 24 hours and 88% after 48 hours. Group A (Control): No significant reduction in CFU counts over time.

Conclusion

Orthodontic bands coated with silver and zinc oxide nanoparticles demonstrated significant antimicrobial activity, with AgNP-coated bands showing superior performance against S. mutans, L. acidophilus, and C. albicans. The results suggest that AgNP and ZnONP coatings could potentially reduce microbial colonization and associated dental complications in orthodontic treatments. Further in vivo studies are recommended to validate these findings.

Keywords: Orthodontic bands, silver nanoparticles, zinc oxide nanoparticles, antimicrobial effect, Streptococcus mutans, orthodontics, biofilm prevention