RESUMEN

Aims: The aim of the study was to compare the activity of sodium hypochlorite (NaOCl) against Enterococcus faecalis when used with four different irrigation protocols. Methodology: Sixty-five single-rooted mandibular premolars with closed apex were prepared till size 35/0.04. The specimens were sterilized and infected with E. faecalis colonies that were cultured separately. The canals were randomly divided into four experimental groups based on irrigation activation protocol, with each group having 15 specimens each - Group 1: control, Group 2: manual dynamic agitation (MDA), Group 3: passive ultrasonic irrigation (PUI), Group 4: intracanal heating (ICH), and Group 5: passive ultrasonic irrigation followed by ICH (PUI ICH). The dentinal shavings were collected and sampled before (S1) and after (S2) the different irrigation techniques were performed. The colony-forming units were counted, and the bacterial reduction was calculated for each group. Results: A significant reduction in the number of E. faecalis colonies was observed for all the experimental groups (P < 0.001). The groups with ICH of NaOCl showed a considerable reduction in bacterial colonies than other groups (P < 0.001), with Group 5 that combined ultrasonics with ICH showed the highest reduction. Conclusion: ICH of NaOCl may be used as an adjunct to root canal irrigation to reduce the bacterial concentration from root canal spaces.