Antibacterial efficacy of ultrasonically activated probiotic endodontic irrigant against Enterococcus faecalis biofilm: an in-vitro study

Abstract

BACKGROUND: Enterococcus faecalis (E. faecalis) is the most frequently retrieved microorganism from teeth with failed endodontic treatment. Sodium hypochlorite (NaOCl) irrigant still poses some drawbacks, such as its cytotoxic effect and reduced effectiveness when applied at lower concentrations. Root canal disinfection by probiotics may yield positive outcomes due to their proven antibacterial and anti-inflammatory abilities. This research was intended to assess the antibacterial efficacy of a probiotic irrigant after ultrasonic activation against E. faecalis in a tooth model. METHODS: Teeth specimens were infected with E. faecalis biofilm and then randomly divided into five groups according to the final flush irrigation protocol used; PRO for probiotic irrigant, PRO + for activated probiotic irrigant, NaOCl for NaOCl irrigant, NaOCl + for activated NaOCl irrigant, and saline for saline irrigation. Activation of the irrigant was done for 1 min using an Ultra X ultrasonic tip. By counting the colony-forming units per milliliter, the antibacterial activity was quantitatively evaluated for each group pre- and post-irrigation application; then, the bacterial load reduction percentages were calculated accordingly. The one-way ANOVA was conducted to compare the mean values of all variables, followed by the post-hoc Tukey test to make group comparisons with a significance level set at p < 0.05. RESULTS: All experimental groups exerted antibacterial activity against E. faecalis with a reduction in the mean CFUs/mL values and an increase in the mean bacterial load reduction percentages. The lowest mean post-irrigation CFUs/mL values were observed in the NaOCl + group, followed by NaOCl, PRO + , PRO, and saline groups respectively. Statistically significant differences were observed among all groups, except for the NaOCl and PRO + groups which did not exhibit any statistically significant difference. CONCLUSION: Ultrasonically activated probiotic irrigant revealed an antibacterial effect similar to the conventional NaOCl and can be effectively used to fight against E. faecalis biofilm.