Effectiveness of Different Irrigant Agitation Techniques on Debris and Smear Layer Removal in Curved Root Canals: A Scanning Electron Microscopy Study

Introduction: The aim of this study was to evaluate the cleaning efficacy of different irrigant agitation techniques on debris and smear layer removal in curved root canals. Methods: Mesiobuccal root canals of 108 mandibular molars were shaped with nickel-titanium instruments, and a final rinse of NaOCl and ethylenediaminetetraacetic acid was performed. Specimens were assigned to 4 groups (n = 20) and submitted to the following irrigation agitation techniques: no agitation (control), ultrasonic, Endo Activator, and CanalBrush. Root canals were split longitudinally and subjected to scanning electron microscopy. The presence of debris and smear layer at coronal and apical levels was evaluated by using a 5-grade scoring system with 200x and 1000 x magnification, respectively. Results: Concerning debris removal, no significant differences among groups were detected. In the coronal region, agitation of the irrigants resulted in significantly more smear layer removal than the control. EndoActivator was significantly more effective than ultrasonic agitation and CanalBrush. Conclusions: In curved root canals, activation of NaOCl and ethylenediaminetetraacetic acid did not enhance debris removal but resulted in significantly more effective smear layer removal at coronal levels. (J Endod 2010;36:1983-1987)