Microbiological evaluation of different agitation methods of irrigation during endodontic procedure – A randomized clinical trial

Introduction: Elimination of microorganisms from the root canal system is a prerequisite for predictable endodontic success. Among persistent pathogens, Enterococcus faecalis poses a significant challenge due to its biofilm-forming capacity and resistance to standard irrigants. This study aimed to compare the antimicrobial efficacy of three irrigation modalities – conventional syringe irrigation, sonic activation, and ultrasonic activation – in reducing E. faecalis colony-forming unit (CFU) counts in infected canals. Methods: Sixty-five patients scheduled for endodontic retreatment were randomly assigned to three irrigation protocols: conventional ( n = 20), sonic ( n = 22), and ultrasonic ( n = 23) irrigation. Microbial samples were collected pre- and postirrigation. Bacterial reduction was evaluated using culture-based CFU analysis, followed by appropriate parametric and nonparametric statistical tests (α = 0.05). Results: Only the ultrasonic group demonstrated a statistically meaningful reduction in CFU levels ( P = 0.011). Comparative analysis revealed a significant difference among the three groups, with ultrasonic activation showing superior antimicrobial effectiveness (ANOVA P = 0.011; Kruskal–Wallis P = 0.0003). Sonic activation produced inconsistent reductions, while syringe irrigation showed a negligible effect. Conclusion: Ultrasonically activated irrigation demonstrated superior antimicrobial efficacy over sonic and conventional techniques, supporting its use as an adjunctive strategy for improved endodontic disinfection.