Antiadherence and Antimicrobial Properties of Copper Oxide Nanoparticles against Streptococcus mutans, Staphylococcus aureus, and Candida albicans on Orthodontic Brackets: An in Vitro Study

Aim: This study aimed to investigate the antimicrobial efficacy and anti-adhesive properties of copper oxide nanoparticle (CuONP) coatings applied to metal orthodontic brackets.Methods: Two hundred forty orthodontic brackets were divided into two groups (n=۱۲۰ each) to assess antimicrobial activity and microbial adhesion. Each group was further subdivided into three subgroups (n=۴۰) based on the test organism: Streptococcus mutans, Staphylococcus aureus, and Candida albicans. Within each subgroup, ۲۰ brackets were coated with CuONPs, and ۲۰ served as uncoated controls. CuONPs were synthesized via chemical reduction and characterized using UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and zeta potential analysis. The dip-coating technique was employed for bracket coating. Antimicrobial activity was assessed by the agar well diffusion method, and microbial adhesion was evaluated through colony-forming unit (CFU) counts. Statistical analysis was performed using the Wilcoxon signed-rank test, with a significance level of P<۰.۰۵.Results: CuONP-coated brackets demonstrated strong antimicrobial activity, with inhibition zones measuring ۹.۵۵ ± ۱.۵۸ mm for Staphylococcus aureus, ۵.۹۷ ± ۳.۸۹ mm for Streptococcus mutans, and ۴.۳۷ ± ۳.۳۵ mm for Candida albicans (P=۰.۰۰۱). Coated brackets also exhibited a significant reduction in microbial adhesion, with CFU counts decreasing from ۷۱۴.۵۵ ± ۱۶۰.۹۰ to ۲۰۱.۱۰ ± ۶۶.۱۶ for Staphylococcus aureus and from ۴۷۴.۴۰ ± ۹۳.۱۳ to ۱۷۱.۲۰ ± ۸۴.۵۴ for Candida albicans (P<۰.۰۰۱).Conclusion: CuONP-coated orthodontic brackets exhibited potent antimicrobial and anti-adhesive effects against key oral pathogens. These findings suggest that CuONP surface modification could serve as an effective strategy to reduce biofilm formation, enhance oral hygiene, and minimize the risk of white spot lesions during fixed orthodontic treatment.

Keywords:

Candida albicans , copper oxide nanoparticles , Orthodontic Brackets , Staphylococcus aureus , Streptococcus mutans