Abstract

Background: Enterococcus faecalis (E. faecalis) is commonly implicated in persistent endodontic infections and has been identified as a major contributor to endodontic treatment failure. Due to the complex anatomy of the root canal system and the persistent bacterial colonization, mechanical preparation alone is often insufficient to completely eliminate bacteria and their toxins. Therefore, the present study aimed to evaluate the antibacterial efficacy of endodontic irrigating solutions.

Objective: To evaluate and compare the antibacterial efficacy of 5.25% Sodium hypochlorite (NaOCl), 2% Chlorhexidine (CHX), and a surfactant-modified 2% Chlorhexidine (CHX Plus™) against E. faecalis biofilms in an in vitro model.

Materials and Methods: An in vitro study was conducted on 66 human mandibular premolars, which were divided into four groups: 5.25% NaOCl, 2% CHX, 2% CHX Plus™, and a negative control group (0.9% NaCl). The root canals were prepared to a master apical file size of #40 and step-back to #80. The samples were inoculated with E. faecalis (ATCC 29212) and incubated for 7 days to allow early biofilm formation. The teeth were then irrigated, the remaining bacteria were collected, and bacterial counts were quantified by colony-forming unit (CFU/mL) enumeration. Data were analyzed using Kruskal–Wallis and Mann–Whitney U tests (p < 0.05).

Results: All experimental irrigants significantly reduced the bacterial load compared to the negative control group (p < 0.001). Both 5.25% NaOCl and 2% CHX Plus™ demonstrated significantly higher antibacterial activity compared to conventional 2% CHX (p < 0.05). No statistically significant difference was observed between the NaOCl and CHX Plus™ groups (p > 0.05), although NaOCl showed the lowest absolute residual bacterial counts.

Conclusion: All three solutions showed high antibacterial efficacy against E. faecalis. However, 2% CHX was less effective than 5.25% NaOCl and 2% CHX Plus™.