Effect of Ultrasonics on Enterococcus faecalis Biofilm in a Bovine Tooth Model

Introduction: The purpose of this study was to evaluate in vitro the effect of the ultrasonic irrigation of sodium hypochlorite and EDTA in root canals of bovine teeth infected with Enterococcus faecalis. Methods: Eighty-four bovine incisors were inoculated with E. faecalis, remaining in culture for 50 days for biofilm formation. The teeth were divided into four groups: the control group, which received no treatment; the ultrasonic + distilled water group; the conventional irrigation with sodium hypochlorite + EDTA group; and the passive ultrasonic irrigation with sodium hypochlorite +. EDTA group. Microbiological tests and analysis in scanning electron microscopy (SEM) were performed. Results: In microbiological testing, groups using sodium hypochlorite did not show bacterial growth. There were significant differences between the control group and the ultrasonic + distilled water group and between these groups and groups using sodium hypochlorite. In SEM analysis, at the canal wall area, there was no significant difference between the groups using sodium hypochlorite, but these were different from the others groups. The control group was significantly different from the ultrasonic + distilled water group. At the exposed tubule area, there was no significant difference between the groups. Conclusions: Passive ultrasonic irrigation can be an aid in cleaning the root canal; however, the main role in bacteria elimination is played by the irrigant. (J Endod 2011;37:1128-1133)