Comparison of the Effect of Probiotic Yogurt-Drink Kefir, % 0.2 Chlorhexidine and % 0.2 Sodium Fluoride Mouthwashes on Streptococcus Mutans: An In vitro Study

Reduction in the number of salivary streptococcus mutans، leads to reducing the caries score. The probiotics are effective in achieving this purpose. The aim of this study was to compare the effect of probiotic yogurt-drink Kefir، 0. 2% sodium fluoride and 0. 2% chlorhexidine mouthwashes on the growth of streptococcus mutans. In this experimental study، microbial suspension from a standard strain of streptococcus mutans PTCC 1683 and 7 isolated salivary strains were inoculated on BHI plates. Two wells were inserted in each plate، one containing the 0. 2% sodium fluoride or 0. 2% chlorhexidine mouthwashes or drink Kefir or 20mg/ml penicillin solution (positive control) and the other contained distilled water (negative control). The inhibition zone around each well was measured after incubation. To determine the minimum inhibitory concentration، in turbidity measurement method، the chlorhexidine، Kefir and penicillin solutions were diluted serially so microbial suspension was added to them. The turbidities of the solutions before and after incubation were measured by ELIZA reader 2 and the minimum concentration with antibacterial effect was reported. There was not halo around the sodium fluoride. The mean diameter of halos for penicillin، chlorhexidine and Kefir was 43. 29 ±4. 68، 27. 38±3. 39 and 19. 88±5. 62 mm، respectively. These differences between all groups two by two were significant (p? 0. 0001). The minimum inhibitory concentration of penicillin، chlorhexidine and Kefir was recorded at the range of 3. 125 - 6. 25%، 6. 25 - 25% and 25 - 50%، respectively. The results of this study showed that Kefir was able to inhibit the Streptococcus mutans more than 0. 2% sodium fluoride but less than 0. 2% chlorhexidine.