Evaluation of cytotoxicity of copper oxide and zinc oxide hybrid nanocoated orthodontic brackets

Using a combination of two nanoparticles for coating stainless orthodontic brackets might alter their potential cytotoxicity. The study investigated the cytotoxicity of brackets nanocoated with copper oxide, zinc oxide and a combination of both the particles. Stainless steel orthodontic brackets (Ormco Mini -Diamond series 0.22” slot, MBT prescription) (ORMCO CORP Glendora, California, USA) (n= 31 in each group) were coated with nanoparticles of copper oxide, zinc oxide and a combination of copper oxide –zinc oxide using a spray pyrolysis method. The brackets was assessed for cytotoxicity in mouse fibroblast (L929) using MTT assay with a standard control and a group of uncoated brackets for comparison. The optical density and percentage of cell viability of the 5 groups were compared with ANOVA and Post hoc Tuckey HSD. P value ≤ 0.05 was considered as statistically significant. The three groups of coated brackets and the uncoated brackets exhibited significantly lesser percentage of cell viability than the control group. The percentage of cell viability in all the four groups was greater than 70% Zinc oxide and copper oxide nanocoated brackets exhibited lesser cell viability than the combination group and the uncoated brackets.Brackets coated with combination of copper oxide and zinc oxide nanoparticles exhibited lesser cytotoxicity than the brackets coated with copper oxide or zinc oxide nanoparticles.