Impact of different agitation methods on smear layer cleaning of mesial canals with accentuated curvature

Objectives The aim of this study was to evaluate the impact of different methods of irrigant agitation on smear layer removal in the apical third of curved mesial canals of 3D-printed mandibular molars. Material and Methods Sixty 3D-printed mandibular second molars with a 70° curvature and a Vertucci type II configuration in the mesial root were used. A round cavity was cut 2 mm from the apex using a trephine of 2 mm of diameter, 60 bovine dentin disks were made and a smear layer was formed. The dentin disks had the adaptation checked in the apical third of the teeth with wax. The dentin disks were evaluated in environmental Scanning Electron Microscope before and after the following irrigant agitation methods: G1(PIK Ultrasonic Tip), G2 (Passive Ultrasonic Irrigation with Irrisonic– PUI), G3 (Easy Clean), G4 (HBW Ultrasonic Tip), G5 (Ultramint X Ultrasonic tip), and G6 (conventional irrigation-CI) (n = 10). All groups were irrigated with NaOCl 2.5% and EDTA 17%. The data was statistically compared (P < 0.05). Results All dentin disks were 100% covered by smear layer before treatment, and all groups significantly reduced the percentage of smear layer after treatment. After the irrigation protocols, the Ultra-X group showed the lowest coverage percentage, statistically differing from the conventional, PIK, and HBW groups (P < 0.05). There was no significant difference among Ultramint X, PUI-Irrisonic, and Easy Clean (P > 0.05). Conclusion None of the agitation methods was able to completely remove the smear layer. The Ultramint X provided a completely clean specimens. Clinical relevance: Removing the smear layer favors better intradentinal antimicrobial action by the intracanal medication and greater penetrability of the filling material into de dentin. This study analyzed different methods and agitation apparatus in the removal of the smear layer in mesial canals of severely curved lower molars. All the agitation techniques employed were unable to fully eliminate the smear layer from all samples. Ultra X showed a higher smear layer removal compared to other experimental groups.