Qualitative analysis of the removal of the smear layer in the apical third of curved roots: conventional irrigation versus activation systems.

INTRODUCTION The aim of this study was to evaluate the effectiveness of different irrigant agitation techniques on smear layer removal in curved root canals. METHODS Mesiobuccal canals of 62 extracted lower molars with a curvature of 33 degrees were used and instrumented up to ProTaper F2. The samples were divided into 3 experimental groups according to the final irrigation: conventional irrigation, ultrasonic irrigation, and sonic irrigation by using the EndoActivator system. The control group was composed of 2 specimens without any final irrigation. In all of the experimental groups, 5 mL of 17% ethylenediaminetetraacetic acid was used for 1 minute, and 5 mL of 2.5% NaOCl was used for 30 seconds. The analysis of the apical region was performed via scanning electron microscopy by 3 examiners. The data were submitted to the Kruskal-Wallis and Dunn tests (P < .05). RESULTS The activation systems removed significantly more smear layer than did conventional irrigation. CONCLUSIONS Sonic and ultrasonic irrigation resulted in better removal of the smear layer in the apical third of curved root canals than did conventional irrigation.