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Evaluation of ultrasonic irrigation systems for debris and smear removal in root canals : a scanning electron microscope study Parhar, Mark Azad


Objective: The aim of this study was to compare the efficacy of continuous flow ultrasonic irrigation systems to conventional syringe irrigation in removing debris and smear layer in straight and curved root canals. Methods: Twenty-four maxillary recently extracted anterior teeth of curvature less than 10 degrees and 24 mesial roots of mandibular molars with a curvature between 15-30 degrees were instrumented to size 40, 0.04 taper and 35, 0.04 taper, respectively, using 3% sodium hypochlorite. The teeth were divided into three experimental groups according to the final irrigation technique: conventional syringe irrigation with a 30 gauge side vented needle, the PiezoFlow Ultrasonic irrigation system, and the VPro StreamClean Ultrasonic irrigation system. In all experimental groups, 15 mL of 3% sodium hypochlorite was used after instrumentation. Both ultrasonic systems were set at a flow rate of 15 mL/min and used for 1 minute at the ultrasonic power setting recommended by the manufacturer. This was followed by 3 mL of 17% EDTA for 2 minutes and 2 mL of sterile water. The teeth were sectioned and prepared for scanning electron microscope observation to assess the presence of debris and smear layer at the apical level (1, 3, 5 mm) with 200x and 1000x magnification, respectively. The debris was graded using Adobe Photoshop CS5 and two calibrated observers using a five-score scale graded the smear. All grading was blinded. The debris data was analyzed using one-way analysis of variance with Dunett’s test and the smear layer scores were analyzed using Kruskal Wallis. Results: Concerning debris removal, no significant differences among groups were detected, however, the PiezoFlow Ultrasonic system approached significance at the 1 and 3 mm levels in the straight canals. The PiezoFlow Ultrasonic system resulted in significantly more smear layer removal at the 1 mm level in the straight canals compared to conventional syringe irrigation. Conclusion. The final irrigation techniques were unable to completely remove debris or smear layer from the apical 5 mm of the straight and curved canals, however, the PiezoFlow removed significantly more smear layer at the 1 mm level in straight canals.

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