Investigation of the Effect of Esterpococcus Mutans Based Aging on Flexural Strength of composite Materials

Introduction: Dental biofilm bacteria can affect the properties of restorative materials by destroying them, so this study was designed to illustrate the effect of aging caused by Streptococcus mutans on the flexural strength of composite restorative materials. Materials & Methods: This study was performed experimentally on composite blocks. The used composite materials included a type of nano-hybrid composite containing Bis GMA (Charisma smart, Kulzer,) and a nano-hybrid composite with a non-Bis GMA (charisma smart diamond) monomer base. Three aging methods were used including aging with water, Streptococcus mutans and germ free culture medium and the three-point flexural strength of the samples was evaluated before and after aging according to ISO_4049 standard. Analysis of variance and Tukey post hoc test were used for statistical analysis. Significance level was considered 0.05. Results: The results showed that the type of composite material and different aging conditions were effective in the flexural strength of composite materials (P = 0.0001). 30-day storage in Streptococcus mutans reduced the flexural strength of both BisGMA and TCD-DI-HEI-based composites (P 0.05). Conclusion: In general, it can be concluded that aging caused by Streptococcus mutans in both restorative materials caused a decrease in flexural strengt