The antibacterial effect of NaOCl (1%, 2. 5%, 5.25%) on 4-, 6-, 10- weeks Enterococcus faecalis biofilms

Abstract

Biofilm is dynamic structure of bacterial populations that surrounded by a polysaccharide extracellular matrix and have been connected to each other. At the same time, the maturity of the biofilm, its structure resistance increase in front of antimicrobial factors.Methods & Materials: In this study, the root canal of 96 human maxillary central teeth debridement under chemicomechanical manner. In order to remove the smear layer, 5.25% hypochlorite sodium solution were used for 3 minutes duration within the channels, then each of the samples immersed in 1 ml of 17%EDTA solution for 3 min. Finally, were done the final washing channels by Phosphate Buffered Saline. After removal of the smear layer, the samples were sterilized. Then, Enterococcus faecalis biofilm were formed 4, 6 and 10 weeks inside teeth root canal and teeth of each group based on the antibacterial therapeutic approach divided into 4 subtypes: group1) 1% NaOCl solution, group2) 2.5% NaOCl solution, group3) 5.25% NaOCl solution and group4) Phosphate buffered saline solution. After preparing the dentin shavings, number of remaining bacteria through the classic method of counting CFU (Colony Forming Unit) was calculated and then compared.Results: In groups 2 and 3 (2.5% NaOCl solution group and 5.25%NaOCl solution) did not grow any bacteria and this approach leads to completely removel of the Enterococcus faecalis biofilm in each of 3stage of developmental growth of biofilm, while the rate of bacteria decreased in group 1 (1%NaOCl) in the biofilm of 4, 6 and 10 weeks, compared to the control group.Conclusion: Bacterial cells that present in the matured and old biofilm are more resistant than young biofilm in front of 1%NaOCl solution, while 2.5% and 5.25% NaOCl solution causes completely inhibition of Enterococcus faecalis bacteria biofilm at each of 3stage of developmental growth of biofilm.