Smear Layer Removal by Irrigation Adjuncts: a Scanning Electron Microscopy Study

Purpose: This study aimed to compare the intracanal smear layer removal ability of two adjunctive irrigation modalities: the AdvErL EVO laser, the GentleWave® Procedure, and their combination, after minimally invasive canal instrumentation. Methods: Forty molars were accessed, the mesiobuccal canals of maxillary and mandibular molars were prepared up to apical size 25.04 using rotary instrumentation, then irrigated using: conventional needle irrigation (CNI), laser-assisted irrigation (LAI), the GentleWave® Procedure (GWP), and LAI followed by GWP (LAI+GWP). The teeth were then decoronated and split longitudinally. One-half of each root was selected for preparation and analysis under scanning electron microscope. Blinded evaluators rated the randomized images on a 4-point scale. Interrater agreement was assessed using Kappa statistic. Nonparametric Kruskal-Wallis test was used to test for associations between the rating and the irrigation method. Post hoc pairwise comparisons were assessed using the Dwass, Steel, Critchlow-Flinger method. Results: The median rating for CNI = 4, LAI = 3, GWP = 2, LAI+GWP = 1.5. The latter three groups resulted in more smear layer removal than conventional needle irrigation, but there was no statistical significance among them (p< 0.05). Conclusion: There was no difference between the AdvErL EVO laser, the GentleWave® Procedure, and their combination, in smear layer removing ability. They all outperformed conventional needle irrigation.