Smear layer removal comparing conventional irrigation, passive ultrasonic irrigation, EndoActivator System, and a new sonic device (Perfect Clean System) by scanning electron microscopy: An ex vivo study.

Aim: This study evaluated the smear layer removal provided by conventional, sonic, and ultrasonic irrigation techniques.

Methodology: Forty extracted human mandibular first premolars were selected and instrumented using the ProTaper Next System files and 2.5% sodium hypochlorite. Afterward, they were divided into 4 groups (n. 10) according to the irrigation technique used to perform the final irrigation with a chelating solution (17% EDTA): conventional irrigation (CI), passive ultrasonic irrigation (PUI), EndoActivator System (EAS), and Perfect Clean System (PCS). The smear layer removal was determined through a score after evaluating scanning electron microscope images (1.000x) obtained at 1, 5, 8, and 12mm from the working length (WL). Statistical analyses were carried out by the Kruskal-Wallis and Dunn's tests with a significance level of 5% (P < 0.05).

Results: All irrigation techniques were unable to promote an effective smear layer removal at 1mm from the WL in comparison with the other locations (P < .05). At 5, 8, and 12mm from the WL, no statistically significant differences were observed among CI, PUI, EAS, and PCS (P > 0.05). At 12mm from the WL, statistically significant differences were only identified after comparing PCS and CI (P < .05).

Conclusion: The smear layer removal was only efficient at 5, 8, and 12 from the WL with no significant statistical differences among CI, PUI, EAS, and PCS (P > 0.05).