Enterococcus Faecalis (E. faecalis) is usually isolated from failed root canal-treated teeth. It can bind to dentin and co-aggregate with other organisms. The organism is resistant to intracanal medicaments and irrigants. It has the ability to produce biofilms and survive within the root canal and it may develop resistance in different phases of the bacterial growth cycle.
Objective: To study the effect of chlorine dioxide on different phases of E. faecalis growth cycle for 1 and 3 min durations.
Methodology: E. faecalis ATCC strain (29212) was grown in different culture phases on dentinal blocks of extracted human teeth. After treatment with chlorine dioxide, the left out colonies were counted from dentinal shavings. Scanning electron microscopic observations of the remaining biofilm in different phases were made and compared among them.
Results: In all 3 phases, in the end of the 1 and 3 min time, significantly fewer (p<0.01, p<0.001 respectively) E. faecalis colonies were observed, compared to the initial count. When comparing the effect of chlorine dioxide on E. faecalis colonies in the three phases, in the end of the 1 min time, significantly fewer (p<0.05) E. faecalis colonies were observed in the exponential phase than in the starvation phase. However, the E. faecalis colony count during the stationary phase was significantly lower (p<0.05) than the colony counts made in both exponential and starvation phases. In the end of the 3 min time, no significant difference in E. faecalis colony count was registered between exponential and starvation phases. However, the E. faecalis colony count during the stationary phase was significantly lower (p<0.05) than the colony counts made in both exponential and starvation phases.