In vitro assessment of the recurrent doses of topical gaseous ozone in the removal of Enterococcus faecalis biofilms in root canals.

AIM To evaluate the potential antibacterial effect of recurrent doses of topical gaseous ozone on the Enterococcus faecalis biofilms0 growth in human root canals in vitro. MATERIALS AND METHODS One hundred and thirty four human single-rooted mandibular premolars were enlarged to a size 35 K-File. Each root canal were inoculated with an overnight culture of Enterococcus faecalis 0ATCC 29212 in tryptic soy broth for 24 hours and incubated for 7 days at 37°C. At 7-day interval, 4 specimens were prepared for Scanning Electron Microscope (SEM) analysis to confirm the presence and purity of biofilms whilst the other contaminated root canals were irrigated and disinfected. One hundred root canals of total 134 specimens were selected to create the experimental groups and divided into 5 subgroups. In each experimental group ( n = 20) root canals), recurrent ozone doses were applied with different irrigation and disinfection protocols in 5 different time intervals. Bacterial growth was analyzed by counting viable E. faecalis on tryptic soy agar plates. RESULTS According to intergroup comparison results observed in the final sample collection analysis, the amount of remaining bacteria in the positive control group were found to be significantly higher compared to Groups 1, 2, 3, 4, 5 and the material control group ( P < 0.01). The remaining amount of bacteria in the last count of Group 1 were found to be significantly higher compared to Group 2 ( P < 0.05), Group 4 ( P < 0.01), Group 5 (P < 0.05) and the material control group (P < 0.01). CONCLUSION The application of topical gaseous ozone in recurrent doses provides a positive effect in the removal of E. faecalis biofilm from root canals. However, during disinfection procedure, the combined use of recurrent doses of topical gaseous ozone with 2% NaOCl enhanced its antibacterial effect against E. faecalis biofilm.