ABSTRACT
Introduction: Biomechanical preparation of root canals isone of the main steps in achieving endodontic success dueto enabling bacterial elimination, removal of debris, andfacilitating obturation. The aim of this study was to comparethe incidence of dentinal cracks observed in the canal wallafter canal instrumentation with 3 single-file systems and theProTaper system (Dentsply Maillefer, Switzerland).Material and Methods: Eighty mandibular premolars withsingle root canal were selected. Teeth were decoronated andmounted in resin blocks with simulated periodontal ligaments.They were divided into 4 experimental groups (n = 20); theninstrumented to the full working length with the ProTaper,OneShape (MicroMega, Besancon, France), Reciproc (VDW,Munich, Germany), and WaveOne Gold (Dentsply Malliefer)was performed. The roots were sectioned perpendicular to thelong axis at 3, 6, and 9 mm from the apex and were observedunder a stereomicroscope. The presence of cracks was noted.The chi-square test was performed to compare the appearanceof cracked roots between the experimental groups.Results: Cracks found after canal instrumentation with theProTaper, OneShape, and Reciproc and WaveOne Goldfiles, were 46.6%, 23.3%, 13.6%, 11.6% respectively. Thedifference between the experimental groups was statisticallysignificant (P < .001).Conclusion: Nickel-titanium instruments cause cracks in rootsurface or in the canal wall; Reciproc and WaveOne Gold filescaused less cracks than the ProTaper and OneShape files.