Efficiency of Canal Brush and Ultrasonic Activated Irrigation in Smear Layer Removal Using Two Different Chelating Agents (In Vitro Study)

Abstract

Objective: This study aims to evaluate the efficiency of two different activation methods after using two different chelating agents inthe removal of the smear layer. Methods: In this study, seventy single-rooted mandibular premolar teeth were included, and divided into six study groups and onecontrol group according to the chelating agents and activation methods used. In groups 1,3, and 5, EDTA was used as the chelatingagent, where it was activated by Canal Brush in G3 and by Ultra Smart in G5. In groups 2,4, and 6, 7% Maleic acid was used insteadand activated by Canal Brush in G4 and Ultra Smart in G6. While in G1 and G2, no activation systems were used. The 7th group wasa negative control and purposed to verify the internal microstructure, so only distal water was irrigated (no activation and no chelatingagent was used). Samples were sectioned longitudinally and prepared for Scanning Electron Microscope (SEM) analysis in the coronal,middle, and apical parts. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests. The level of significancewas set to 0.05 (P < 0.05). Results: Although the G5 (Ultra Smart +EDTA) median score showed the best smear layer removal score, it was not statisticallysignificant in comparison with the other 5 study groups. In all groups (whether Maleic acid or EDTA were used), smear layer removalwas effective in the coronal and middle thirds while less effective in the apical third, with no statistically significant difference betweenthe chelating agents. Conclusions: Under the limitations of this in vitro study, no activation system was able to remove the smear layer from the root canalwall completely. However, NaOCl and EDTA's irrigation sequence combined with Ultra Smart (ultrasonic activation) obtained betterresults than the other techniques.