Comparison of antibacterial effects of ZnO and CuO nanoparticles coated brackets against streptococcus mutans

Statement of the Problem: During the orthodontic treatment, microbial plaques may accumulate around the brackets and cause caries, especially in high-risk patients. Finding ways to eliminate this microbial plaque seems to be essential

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Purpose: The aim of this study was to compare the antibacterial effects of nano copper oxide [CuO] and nano zinc oxide [ZnO] coated brackets against Streptococcus mutans [S.mutans] in order to decrease the risk of caries around the orthodontic brackets during the treatment

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Materials and Method: Sixty brackets were coated with nanoparticles of ZnO [n=20], CuO [n=20] and CuO-ZnO [n=20]. Twelve uncoated brackets constituted the control group. The brackets were bonded to the crowns of extracted premolars, sterilized and prepared for antimicrobial tests [S.mutans ATCC35668]. The samples taken after 0, 2, 4, 6 and 24 hours were cultured on agar plates. Colonies were counted 24 hours after incubation. One-way ANOVA and Tukey tests were used for statistical Analysis

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Results: In CuO and CuO-ZnO coated brackets, no colony growth was seen after two hours. Between 0-6 hours, the mean colony counts were not significantly different between the ZnO and the control group [p>0.05]. During 6-24 hours, the growth of S.mutans was significantly reduced by ZnO nanoparticles in comparison with the control group [p< 0.001]. However, these bacteria were not totally eliminated

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Conclusion: CuO and ZnO-CuO nanoparticles coated brackets have better antimicrobial effect on S.mutans than ZnO coated brackets