Susceptibility of Enterococcus faecalis to different experimental and conventional intracanal-medicaments

Objectives: The first aim of this study was to convert a medical disinfectant solution into a gel by using two different biopolymers as vehicles in order to prolong disinfectant residence time in the root canals, improve its therapeutic effect and achieve usage as an intracanal-medicament. Second aim was to assess the susceptibility of a resistant Enterococcus faecalis strain to four new gels (Experimental gel-1, Experimental gel-2, Experimental gel-3, and Experimental gel-4) and known intracanal medicaments (Calcium hydroxide-Sultan Chemists, Englewood, NJ mixed with distilled water and glycerin (1:7 ratio), CALXYL-Oco Praparate GmbH, Dirmstein, CALXYL Suspension-Oco Praparate GmbH, Dirmstein, Consepsis 2% Chlorhexidine gel-Ultradent, USA).

Methods: Filter paper discs were immersed in spectrophotometrically standardized bacterial suspension ((OD₆₀₀=0.500) for 20min and exposed to intracanal-medicaments and freshly prepared gels in teflon wells and incubated at 37̊C, 100% humidity, for 12 hours. After incubation the filter paper discs were transferred to vials with PBS and glass beads and vigorously shaken for dispersal of the bacterial cells. PBS with resuspended bacteria was serially diluted 10-fold. Droplets of 25 ìL from each dilution were inoculated on Tryptic Soy Agar plates and incubated at 37̊C for 24 h. The number of colony-forming units was then calculated from appropriate dilutions and statistically analyzed with using Mann Whitney-U test.

Results: All experimental gels killed E. faecalis microorganism to a level below the detection limit except experimental gel-1 which was having less concentration of the disinfectant. Experimental gel-1 exhibited some effectiveness in reducing this bacterium when compared with E. faecalis infected filter-membrane control group. Calcium hydroxide mixture with distilled water and glycerin was more effective than CALXYL paste and suspension and killed all the bacteria.

Conclusion: It seems that experimental three gels can be considered as possible alternative antimicrobial intracanal agents to the use of conventional chlorhexidine gel and calcium hydroxide medicaments.