The efficacy of different irrigant activation methods in the elimination of bacteria colonizing in dentin tubules.

Purpose: The purpose of this ex vivo study was to investigate the effects of 5 distinct irrigant activation systems on bacterial colonization within dentinal tubules utilizing confocal laser scanning microscopy (CLSM). Materials and Methods: Sixty extracted human mandibular premolars with single canals were prepared using resiprocal instruments. The teeth were embedded in acrylic resin blocks and the root canals were inoculated with Enterococcus faecalis. Root canals were irrigated using five different irrigant activation methods: standard needle irrigation, IrriFlex, EDDY, Endoactivator, and passive ultrasonic irrigation (PUI). Horizontal sections, 1 ± 0.1 mm in thickness, were obtained at distances of 2, 5 and 8 mm from the apical end of the teeth. Sections were visualized using a CLSM. The penetration depth of dead bacteria was measured to evaluate the antimicrobial efficacy of the irrigant activation systems. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni correction. Results: PUI showed significantly greater penetration depth of dead bacteria in both the coronal and apical thirds compared to the other experimental groups (p<0.05). Conclusion: Although a statistically significant reduction in bacteria was observed in all experimental groups compared to the control, the canal disinfection was not complete in any of the groups. According to our results, standard needle irrigation had the lowest disinfection efficiency, while PUI demonstrated the highest among the evaluated activation methods.