Shaping ability of four nickel-titanium rotary instruments in simulated S-shaped canals

Introduction: The purpose of this study was to comparethe shaping ability of ProTaper, Mtwo, BioRaCe, andBioRaCe + S-Apex instruments in simulated canals withan S-shaped curvature. Methods: Canal transportationand aberrations were assessed by comparing the preinstrumentationand postinstrumentation images undera stereomicroscope. Analysis of variance and post hocStudent-Newman-Keuls test were used for statisticalanalysis. Results: ProTaper instruments caused morepronounced canal transportation in the apical curvature(P < .01) than all other instruments. The use of ProTaper,Mtwo, and BioRaCe instruments resulted in morecanal aberrations compared with BioRaCe + S-Apex(P < .05). Conclusions: NiTi systems including lesstapered and more flexible instruments like S-Apexseem to be favorable when preparing S-shaped canals