Comparative efficacy of irrigation activation systems in root canal cleanliness: a region-specific analysis of debris and smear layer removal.

This study aimed to compare the efficacy of four irrigation activation systems against conventional needle irrigation (CNI) in removing debris and smear layer from root canal. Forty human single-rooted teeth premolars were instrumented to a consistent size and randomly divided into five groups (n = 8/group), namely CNI, and other activation groups including EDDY, Gentlefile, passive ultrasonic irrigation (PUI), and shock wave-enhanced emission photoacoustic streaming (SWEEPS) techniques. After irrigation, the roots were split longitudinally and debris and smear layer in coronal, middle, and apical thirds were evaluated by scanning electron microscope (SEM). Scores were analyzed using Kruskal-Wallis test followed by Dunn's post-hoc test with Bonferroni correction. For debris removal, the EDDY and SWEEPS groups showed significantly lower scores than CNI in the coronal and apical thirds (p < 0.05), while PUI and Gentlefile did not; in the middle third, all activation groups achieved significantly lower scores than CNI (p < 0.05). For smear layer removal, only SWEEPS was superior to CNI in the coronal third (p < 0.05); in the middle third, all activation groups achieved significantly lower scores than CNI (p < 0.05); in the apical third, EDDY and SWEEPS performed better than CNI (p < 0.01), but PUI and Gentlefile did not. Activated irrigation techniques show region- and target-dependent efficacy. All activation groups demonstrated significant improvements over CNI in the middle third, but only EDDY and SWEEPS maintained this significant improvement in the apical third.