A Promising Probiotic Irrigant: An In Vitro Study

AIM: The present study aimed to investigate the inhibitory effect of Lactobacillus rhamnosus (B-445) as a probiotics irrigant on the growth of Enterococcus faecalis. METHODS: Forty-two extracted single human canal anterior teeth were prepared with rotary instrumentation and sterilised. Teeth were divided into 3 groups according to the type of irrigant, N = 14. Three experimental groups were inoculated with E. faecalis and cultured for 21 days before use; Group 1 was 2.5% NaOCl (positive control), Group 2 was saline (negative control), Group 3 was the experimental probiotic irrigant. Paper point sampling of the canals of each group was obtained before irrigation (S1), immediately after irrigation (S2) and after 24 hours (post irrigation samples) (S3) to determine remaining colony forming units for E. faecalis. Also, Colony counts for L. rhamnosus in Group 3 after immediate irrigation, as well as 24 hours post irrigation, was performed to determine the survival profile of these bacteria in infected root canal with E. faecalis. RESULTS: The NaOCl irrigant group had the lowest mean value of (log 10 CFU/mL) of E. faecalis after immediate irrigation and after 24 hrs post irrigation followed by the probiotic group, while the highest mean value was the saline group (P ≤ 0.001). The survival profile for L. rhamnosus in Group 3 after immediate irrigation and post-irrigation were slightly higher than for E. faecalis (P ≤ 0.001). CONCLUSION: Lactobacillus rhamnosus which revealed a potential inhibitory effect on the growth of Enterococcus faecalis, could be used as a new natural, safe probiotic irrigant agent.