Effect of sonic and ultrasonic irrigation on improving root canal cleanliness after post space preparation: A confocal laser scanning microscopic study

Abstract

Introduction: Removing the secondary smear layer has been presumed to increase the micromechanical retention of fiber posts. The additional use of irrigation techniques is intended to improve the cleanliness of the root canal walls. The present study aimed to determine the effectiveness of sonic and ultrasonic irrigation techniques on root canal cleanliness after the post space preparation. Materials and Methods: A total of 27 extracted single-rooted premolar samples underwent root canal treatment using gutta-percha and AH Plus that was labeled with rhodamine B. Gutta-percha was removed during the post preparation. The sample was then divided into three groups (n = 9): irrigation with sonic activation, ultrasonic activation, or without activation, respectively. The teeth were subsequently cut in the middle third area of the root, and the remnant of smear layers was observed using a confocal laser scanning microscope. Cleanliness was expressed as a percentage of the angle that contained part of the red area representing the smear layer. The results were statistically analyzed with a one-way ANOVA test and post hoc Bonferroni test set at 5% significance level. Results: The sonic group had the greatest percentage of root canal wall cleanliness (89.00 ± 2.77), followed by the ultrasonic (78.33 ± 3.09) and nonactivated groups (67.77 ± 3.37). Conversely, there was no significant difference in root canal wall cleanliness between the sonic and ultrasonic groups (P = 0.067) or the ultrasonic and nonactivation groups (P = 0.071). Conclusions: Irrigation with sonic activation improved cleanliness of the root canal dentinal wall after post space preparation.