Removal of the smear layer by passive and continuous ultrasonic irrigation: a scanning electron microscopy study

Background: Due to the anatomical complexity of root canal system, irrigation plays an essential role in endodontics. This vitro study was sought compare removal smear layer (RSL) promoted by conventional (CI), passive ultrasonic (PUI) and continuous (CUI) with 17% EDTA, using scanning electron microscopy (SEM). Material Methods: Forty single-rooted human mandibular canines were instrumented randomly assigned four groups (n=10), according protocol aiming RSL: CG (control group) —conventional distilled water; CI— EDTA; PUI —passive CUI— EDTA. Hemisections from each sample obtained, images third (cervical, middle apical) captured at 1000 X magnification SEM. Three previously calibrated blinded evaluators classified RSL, criteria proposed Torabinejad et al.: small or no (all dentinal tubules clean open); 2 = moderate (no on surface canal, but contained debris); 3 dense (covering practically all entrances). Statistical analysis performed Kruskal-Wallis Bonferroni tests (p<0.05). Results: Overall, CUI cervical thirds showed better RSL rates, compared other methods thirds, respectively More specifically, results CG, CI (p<0.05), whereas not significantly different group. Conclusion: most effective method for RSL.