Investigation of the effect of different irrigation systems on dentin tubule penetration and push-out bond strength of root canal sealer

Investigation of the Effect of Different Irrigation Systems on Dentin Tubule Penetration and Push-out Bond Strength of Root Canal Sealer The aim of this in-vitro study was to compare the effect of different irrigation systems (conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), EndoActivator (EA), EDDY) on dentin tubule penetration and bond strength to root dentin of root canal sealer. In our study, 90 mandibular premolar teeth were used. The teeth were randomly assigned to four experimental (n=20) and a control groups (n=10). Teeth in each group were shaped with T-Endo Must files to apical diameter #40/.04. While final irrigation was not applied in the control group, final irrigations of teeth in four experimental groups were activated using CNI, EDDY, EA and PUI (Irrisafe). The root canal filling was performed with the lateral condensation method using gutta-percha and labelled AH Plus canal sealer with fluorescent dye. Transverse sections of 1 ± 0.1 mm thickness were taken from the teeth at 2, 5, 8 mm distances from the apical with a microcut device, respectively. Images were taken with a Confocal Laser Scanning Microscope under 4x magnification. The dentinal tubule penetration area, percentage and maximum tubule penetration depth were measured with the Image J program on the taken images. The dentinal adhesion of the sealers were evaluated by applying push-out bond strength test to the sections taken. Kruskal Wallis and Tamhane's T2 tests were used for statistical analysis. The maximum dentin tubule penetration depth values of the root canal sealer in the control group were lower than all experimental groups in the apical and middle third, and only EDDY, EA, and PUI groups in coronal third (p<0.05). The dentin penetration percentage values of the root canal sealer in the control group were lower than EDDY in the apical third, and PUI, EDDY, and EA groups in the coronal third (p<0.05). In the middle third, the control group showed lower penetration percentage values than EDDY and PUI, and the CNI group than EDDY (p<0.05). The dentin tubule penetration area values of the root canal sealer in the control group were found to be lower than all experimental groups in the apical and middle third, and only EDDY, EA and PUI in the coronal third (p<0.05). In addition, the dentin tubule penetration values of the root canal sealer in the control and all experimental groups increased from apical to coronal. It was found that the experimental groups showed higher bond strength values than the control group (p<0.05). When the correlations of push-out bond strength and dentin tubule penetration depth, area and percentage values of the root canal sealer were compared, a statistically significant but weak correlation was found (0.20-0.39). Within the limitations of the study, the experimental groups that were activated in all parameters and sections (apical, middle, coronal) resulted in higher dentin tubule penetration and bond strength values than the control group. More studies are needed comparing EDDY, a new sonic activation system, with other activation systems. Keywords: bond strength, dentin tubule penetration, irrigation, confocal laser scanning microscope