Effectiveness of different irrigant activation techniques in removing smear layer: a scanning electron microscope study

Background: This study aimed to evaluate the efficiency of Laser-Activated-Irrigation, XP-Endo Finisher, and Endo Activator irrigation protocols in removing the smear layer from root canal walls by evaluating the opening of the dentinal tubules in the coronal, middle, and apical thirds using scanning electron microscopy. Materials and Methods: Thirty single-rooted human anterior teeth were decoronated to a standardized length. The samples were prepared using the primary WavOne Gold rotary system and divided into 3 groups (n=10): Laser-Activated-Irrigation (LAI), XP Finisher and Endo Activator. In addition to the control group, which was irrigated with a conventional syringe only. The teeth were split longitudinally and examined under SEM at 1000x magnification. Images were taken at apical, middle, and coronal thirds. Data were analyzed using the Kruskal-Wallis test, with a significant p-value being less than 0.05. Results: Upon examining the removal of the smear layer in the root canal under 1000x magnification, there were no statistically significant differences in the coronal, middle, and apical third between the three studied groups. However, the study revealed significant differences compared to the control group. The LAI demonstrated a minimal smear layer and open dentinal tubules in the coronal and middle thirds, however, a smear layer was still present in the apical third. The XP-Endo Finisher effectively produced a thin, homogeneous smear layer with fewer open dentinal tubules, partic-ularly in the apical third. In contrast, the Endo Activator resulted in a uniform smear layer with minimal tubule exposure in the coronal third, but it covered over 50% of the apical third. No significant differences among root thirds were observed, and complete smear layer removal was not achieved in the apical third with any method. Conclusions: XP-Endo Finisher was the most effective method in removing the smear layer in the apical third. Endo Activator was found to be the best in the middle third. Finally, LAI was determined to be the most effective in removing the smear layer in the coronal third. In clinical practice, it is recommended to use different techniques for cleaning different parts of the canal. Conventional nee-dles for irrigation are less effective. Using these advanced techniques can significantly improve root canal treatments.