Comparative inhibitory activity of new-antiseptic octenidine-hydrochloride solution on Enterococcus faecalis

Objectives: To determine the minimum inhibitory concentration (MIC) of a new antiseptic solution used in medicine for traumatic, acute, chronic, surgical or burn wounds; octenidine hydrochloride (OCT) (Octenisept®, Schülke&Mayr,Germany) in comparison with 2.5% and 5.25% sodium hypochlorite (NaOCl) (CaglayanKimya,Turkey) and 2% chlorhexidine gluconate (CHX) (Imicyrl,Turkey) required to kill Enterococcus faecalis. Methods: The MIC test was prepared in sterile 96-well microtiter plates. Initially, each well received 150 μl of sterile phosphate saline solution (PBS) and then 150 μl of the test irrigant were added to first well. After serial two-fold dilutions up to ten different concentrations, 150 μl of spectrophotometrically standardized E. faecalis inoculum was added into each well. 300 μl of bacterial suspension (positive) and 300 μl of sterile PBS (negative) were served as control groups. Subsequently, the first spectrophotometric reading was carried out and then the growth of surviving bacteria was measured at the end of the 6, 12, 18 and 24 hours. The microplates were kept at 37ºC under aerobic conditions. After the determination of MIC values with the spectrophotometric readings, the minimal bactericidal concentration (MBC) was determined by inoculating 25 μl from each diluted well on Brain Heart Agar plates at 37ºC for 48 hours. Results: MIC and MBC values (µg/ml) for E. faecalis were 0.64 and 0.128 for OCT, 12.5 and 6.25 for 2.5% NaOCl, 6.56 and 3.28 for 5.25% NaOCl, 0.156 and 0.078 for CHX. The antimicrobial effectiveness of the test irrigants were listed from highest to lowest as follows: CHX, OCT, 5.25% NaOCl and 2.5% NaOCl. Conclusion: Within the limitations of this in vitro study, it can be concluded that octenidine hydrochloride is a potent antibacterial solution that might be used as an alternative irrigant in endodontics. Further research is needed in order to prove other expected properties from octenidine hydrochloride for endodontic use.