In vitro comparison of Streptococcus mutans adhesion to orthodontic composites in various types of saliva

Background&Aim: Considering the increased microbial load of Streptococcus mutans in patients with orthodontic appliances and the high prevalence of caries in these patients, the aim of this study was to compare the adhesion of Streptococcus mutans to orthodontic composites in various saliva types under laboratory conditions at the Tehran Islamic Azad University of Medical Sciences in 1401-1402.Materials and Methods: This research was done experimentally and in vitro.This study was conducted on light-cured composite Sci-pharm and American Orthodontics (6 samples per group).After preparation and sterilization, samples were immersed for 2 hours in one of the artificial saliva compositions with normal or acidic pH.Then, the samples were incubated in a suspension of Streptococcus mutans bacteria for 2 hours.The samples were washed with normal saline and sonicated in 0.9% saline solution to detach the bacteria adhered to the samples.After serial dilution and bacterial culture on brain heart infusion broth, the total number of formed colonies was counted and calculated.The results were graphed using Microsoft Excel software, and the statistical difference between groups was analyzed using two-way ANOVA with a significance level of 0.05 (p < 0.05) in SPSS (last version) software.Results: The adhesion of Streptococcus mutans in acidic and normal saliva to Sci-pharm composites is greater than American Orthodontics composites (P =0.000).The adhesion of Streptococcus mutans to composites in acidic saliva is higher (P = 0.003). Conclusion:American Orthodontics composite exhibits greater resistance to Streptococcus mutans colonization and the adhesion of streptococcus mutans to composites is higher in acidic saliva.