Bacterial Reduction in Oval-Shaped Root Canals After Different Irrigant Agitation Methods

OBJECTIVE: This study aimed to assess the antibacterial effect of Easy Clean®, passive ultrasonic irrigation and sonic irrigation against Enterococcus faecalis biofilm in oval-shaped canals. METHODS: Fifty-five extracted human teeth with similar dimensions were selected. Access cavities were prepared and the root canals were instrumented using Wave One® Primary files (25.08). The root canals were then contaminated with an E. faecalis suspension following incubation for thirty days. The contaminated roots were divided into three experimental groups (n=15) according to the irrigant agitation protocol (Easy Clean, passive ultrassonic irrigation and sonic irrigation), in addition to a positive control group (n=5) and a negative control group (n=5). Microbiological samples were taken from the root canals before instrumentation (S1), after instrumentation (S2) and after the final irrigation protocol (S3). The samples were assayed and incubated for 48 hours in order to obtain the residual titer of E. faecalis cells. Viable cells were quantified by colony-forming units (CFU) measurement. The collected data was submitted to statistical analysis by using Shapiro-Wilk`s test, Wilcoxon paired test, Kruskal–Wallis test and Dunn’s post-hoc test. The level of significance was set at 5%. RESULTS: All experimental groups presented significant reduction on bacterial load after instrumentation (P<0.05) with similar reduction among the groups. After the agitation protocols, significant reduction in bacterial load was demonstrated for all groups (P<0.05). However, no differences were shown among Easy Clean®, PUI and SI (P>0.05). CONCLUSION: The results showed that all tested groups exhibited similar disinfection effectiveness. However, none of them was able to render all root canals free from microorganisms.