Cleaning efficacy of hand and rotary instrumentation techniques in oval-shaped root canals : scanning electron microscopic study

Objective: To assess the cleaning efficacy of the Mtwo rotary system, hand instrumentation and their combination in oval-shaped root canals. Methods: Thirty human mandibular incisors were divided into three groups (G): GMtwo – basic series (10.04, 15.05, 20.06, 25.6) and instruments 30.05, 35.04, 40.04 from complementary series; GMtwo + Hand – basic series of Mtwo followed by sizes 30 to 40 hand instruments; GHand – classic technique with sizes 15 to 40 hand instruments. Teeth were longitudinally sectioned and then the buccal and lingual root canal walls were observed by scanning electron microscopy (SEM). Central images of each canal third were obtained and classified into scores based on the amount of smear layer (SL) and organic debris (OD). Data were analyzed by Kruskal-Wallis and Friedman tests. Results: There was no significant difference between groups (P>0.05) regarding SL. The coronal third showed significantly lower scores than the other segments (P0.05). Conclusion: None of the techniques were completely effective in cleaning oval-shaped root canals. The apical third was the area with higher amount of SL