Antibacterial Effect of Different Concentration of Boric acid against Enterococcus Faecalis Biofilms in Root Canal

The aim of this study was to investigate the antibacterial effects of different concentration of boric acid in root canals that were infected with Enterococcus faecalis biofilms. 104 single-canal premolar teeth were prepared and then disinfected and sterilized. E.faecalis were inoculated into the root canals and kept at 37°C for 24 hours. The re-inoculation procedure was repeated on the first, fourth, seventh and tenth days with fresh culture. The infected root canals were divided into one negative (saline), one positive (sodium hypochlorite) control group, and three experimental groups (boric acid; 2%, 4% and 6%) (n=20). Paper points were placed in root canals before and after irrigation to control and evaluate the biofilm formation. Biofilms were counted on blood agar plates, and the data were evaluated and statistically analyzed using one-way ANOVA and Tukey’s test. There were statistically significant differences among three experimental group (boric acid; 2%, 4% and 6%). Although 6% concentration of boric acid indicated the highest antibacterial effect, it could not exhibit the same antibacterial effect as NaOCl. As a new product boric acid indicated considerable bactericidal effect against E.faecalis biofilms. However, the use of boric acid can be advisable with high concentrations and long irrigation time for root canals disinfection.