Ex vivo study of different final irrigation protocols against mature biofilms in root canal system disinfection

In endodontics the main objective is the debridement and disinfection of the root canal system. The purpose of this study was to evaluate the effectiveness of final irrigation protocols using different irrigation systems, with and without using sodium hypochlorite (NaOCl) as an irrigant, in promoting the disruption of mature biofilms in moderately curved root canals. Sixty mesial roots from extracted human mandibular molars were used. The root canals were contaminated with a standard strain of Enterococcus faecalis for 21 days. Before instrumentation, bacterial samples were collected by inserting a sterile paper point into the root canals. The root specimens were then randomly divided into 6 groups (n = 10) for instrumentation and final irrigation: NaOCl + MI: sodium hypochlorite + manual irrigation; NaOCl + PUI: sodium hypochlorite + passive ultrasonic irrigation; NaOCl + ECL: sodium hypochlorite + irrigation with EasyClean; SS + MI: saline + manual irrigation; SS + PUI: saline + passive ultrasonic irrigation; SS + ECL: saline + irrigation with EasyClean. After the final irrigation, a second sample collection was performed for viable bacterial counts following the same protocol used for the baseline collection. The results were analyzed using Wilcoxon and Friedman nonparametric tests at a significance level of 5%. All final irrigation protocols resulted in significant biofilm reduction within the root canal system (p < 0.05). It can be concluded that the irrigating solution influenced biofilm reduction in the root canal system, regardless of the final irrigation protocol used.