Critical concentrations of surfactant combination regimens with MTAD™ on vancomycin-sensitive Enterococcus faecalis

Abstract

Background: Enterococcus faecalis is an opportunistic pathogen with greater virulence traits and has gained significance in endodontic literature. It is resistant to most irrigants and medicaments with significant posttreatment reversal cultures. The purpose of this study was to evaluate the critical concentrations of irrigants and surfactants and the possible outcome of the combination regimen on E. faecalis. Methods: Five percent sodium hypochlorite (NaOCl), chlorhexidine (CHX), iodine potassium iodide (IKI), and surfactants such as cetrimide (CTR) and sodium dodecyl sulfate (SDS) were prepared. BioPure™ MTAD™ served as control. Minimum inhibitory concentration was performed to determine the dilution fold and dilution factor by serial dilution, followed by minimum bactericidal concentration on agar plates. Results: Although CHX performed better than MTAD™, it proved to be bacteriostatic in action at lower concentrations. NaOCl and IKI were found to be inferior and were excluded. CTR was found to be better than MTAD™; while SDS showed insignificant results. The combination surfactant regimens (CHX + CTR; CHX + SDS) performed in a synergistic fashion and achieved higher eradication rates. Bactericidal action with narrow margins between critical concentrations was recorded and found to be superior to any test irrigant, including MTAD™. Conclusion: Critical concentrations of surfactant combination regimens were found to be highly effective at lower dilutions on E. faecalis. This combination can overcome the limitations, potentiate antimicrobial spectrum, and increase the substantive antimicrobial action of CHX application in clinical endodontics.