Comparing the Effect of Probiotic and Non-probiotic Yogurt Drinks on Two Common Oral Microorganisms: An In Vitro Study

Background and purpose: Decrease in the number of oral microorganisms leads to reduction in caries score. Bacterial therapy, such as using probiotic bacteria, is an alternative procedure in treatment of infections caused by microorganisms. The purpose of this study was to compare the effect of probiotic and non-probiotic yogurt-drink on two common oral microorganisms. Materials and methods: In this experimental study, the minimum inhibitory concentration (MIC) of yogurt drinks and diameter of the growth inhibition zone of Streptococcus mutans and Enterococcus faecalis in probiotic and non-probiotic yogurt drinks were measured using micro broth dilution and disk agar diffusion methods, respectively. Data analysis was done in SPSS V22 applying Mann-Whitney test. Results: The MIC of non-probiotic yogurt drink against Enterococcus faecalis and Streptococcus mutans was significantly higher than the probiotic yogurt drink (P= 0.002). The two yogurt drinks did not show any significant differences in the diameter of growth inhibition zone for S. mutans (P= 0.061) and E. faecalis (P= 0.99). Conclusion: The study showed that probiotic yogurt drink can inhibit E. faecalis and S. mutans more than the non-probiotic yogurt drink, and it may be considered as a preventive agent for oral and dental diseases.