Evaluation of zinc oxide nanoparticle coated elastomeric modules and it's effect on Streptococcus mutans concentration and enamel mineralization - A randomized split mouth trial.

To assess the long term effects of zinc oxide (ZnO) nanoparticle coated elastomeric modules on S. mutans concentration and enamel mineralization among orthodontic patients over a period of one year. A total of 16 patients were recruited for this study. Either the left or right maxillary lateral incisor received the coated module. Group I : ZnO coated elastomeric modules (N = 16); Group II: Non-coated elastomeric modules (N = 16). S. mutans in plaque was assessed at the end of 3 months and one year using Rt -PCR. Enamel mineralization was assessed by laser fluorescence at the end of one year. Integrity of the ZnO nanoparticle coating over a period of one month on a weekly basis was also assessed. Independent t-test was done to find the significant difference between the bivariate samples and intra-group comparison was done using paired t-test. Pearson's correlation was done to determine the relationship between the variables. For all the statistical tests, p < 0.05 was considered to be statistically significant. S. mutans concentration at the end of three months and one year was higher in the non-coated group compared to the coated group but it was statistically significant only at the end of one year (p value = 0.032). Laser fluorescence values was higher for the non-coated group compared to the coated group which showed statistical significance (p = 0.020). ZnO coating of the modules showed evidence of disintegration of the coating after two weeks, with further deterioration of the coating at the end of one month. As elastomeric modules are changed periodically, this appears to be a viable option, especially since the nanoparticle release would be around the most common area of plaque retention.