LAUSR

The aim of this study was to evaluate the effectiveness of SmearOFF solution on smear layer removal by using different irrigation activation techniques. One hundred and twenty mandibular premolars were decoronated, and instrumented with Reciproc up to size 50. Then, the specimens were divided into 6 groups according to the final irrigation activation technique: Group 1: SmearOFF + Conventional syringe irrigation (CSI); Group 2: SmearOFF + Sonic activation (SA); Group 3: SmearOFF + Passive ultrasonic activation (PUA); Group 4:17% EDTA + CSI; Group 5:17% EDTA + SA, and Group 6:17% EDTA + PUA. Teeth were split longitudinally, and specimens were observed under scanning electron microscope. Images were taken from the coronal, middle, and apical thirds of the teeth with 1,000× magnification and analyzed using ImageJ program to calculate total open dentinal tubule areas. Three‐way ANOVA test was applied to reveal any significant differences among solutions, activation techniques and root thirds. There was no statistically significant difference among the groups in terms of irrigation solutions (p > .05). There was a statistically significant difference between PUA and CSI groups (p < .05). However, no significant difference was observed between PUA and SA, or between SA and CSI (p > .05). All experimental procedures were most effective in the middle region of the root, followed by cervical and apical thirds (p < .05). PUA showed higher efficacy in smear layer removal compared with CSI. SmearOFF and 17% EDTA showed similar results. The best results in removing smear layer were obtained in the middle region of the root.