Recent innovations in endodontic irrigation and effects on smear layer removal: an ex-vivo study

Objectives To evaluate the cleaning efficacy of different irrigation activation techniques in removing smear layers from root canals. Materials and methods Ninety lower premolars with straight root canals were assigned to six experimental groups (n = 15 each): control group, conventional irrigation, passive ultrasonic activation (PUI), distilled water laser-activated irrigation (LAI), PulpSucker irrigation, and iVac irrigation. Each canal was shaped to size 30/04 and irrigated with 5% NaOCl. The final rinse was performed according to the experimental group. After chemo-mechanical procedures, the teeth were split longitudinally and subjected to scanning electron microscopic (SEM) analysis for each root canal third (coronal, middle, and apical). The presence of smear layer was evaluated using a 5-grade scoring system at 500x and 1000x magnification. Following the Shapiro-Wilk test, data were statistically analyzed using the nonparametric Kruskal-Wallis test, followed by the post-hoc Dunn test with Bonferroni correction (alpha = 5%), to compare the effectiveness of smear layer removal. The Friedman test and post-hoc Wilcoxon signed-rank test with Bonferroni correction (alpha = 5%) were performed to assess significant differences in smear layer removal among the different tooth thirds. Results Activated irrigation techniques significantly outperformed conventional irrigation (p <.05), with the iVac technique demonstrating the best results in smear layer removal in the apical third. LAI and PUI showed comparable results across all tooth thirds. Significant differences in cleaning efficacy were observed among the different tooth thirds within each experimental group, with the apical third exhibiting the highest presence of smear layer. Conclusion Within the limitations of the study, irrigant activation demonstrated higher efficiency in smear layer removal from root canal systems compared to conventional irrigation techniques. iVac showed the best cleaning performance in each third, particularly in the apical third.