Comparative Evaluation of Shaping Ability and Cleaning Efficiency of Three Different Nickel-Titanium Rotary Systems

Objective: This study was conducted to compare the shaping ability and cleaning efficiency of Mtwo, ProTaper Next and HyFlex CM rotary systems. Materials and Methods: A total of 45 root canals with curvatures ranging between 20o and 40o were divided into three groups of 15 canals: Mtwo, ProTaper Next and HyFlex CM based on pre-instrumentation radiographs. Canals were prepared to an apical size of 30. Using pre- and post-instrumentation radiographs, canal straightening was determined with a computer image analysis program. Preparation time was also recorded. These data were analysed using one-way analysis of variance (ANOVA) and post hoc Tukey’s test, and significance was set at P < 0.05. The amounts of debris and smear layer were quantified based on a numerical evaluation scale and were analysed statistically using the Kruskal–Wallis test. Results: HyFlex CM and ProTaper Next maintained the canal curvature significantly better than Mtwo (P < 0.05). ProTaper Next was significantly faster than the other two systems (P < 0.05). For debris removal, Mtwo and ProTaper Next achieved significantly better results (P < 0.05) than HyFlex CM in the apical and middle canal thirds. The smear layer results were not significantly different for the different parts of the canals (P > 0.05). Conclusions: Under the conditions of this study, HyFlex CM and ProTaper Next maintained the original canal curvature better than Mtwo. The use of Mtwo and HyFlex CM required more time to prepare the curved canals. Mtwo and ProTaper Next resulted in better canal cleanliness compared with HyFlex CM.