To compare the incidence of dentinal defects after canal preparation with different nickel-titanium rotary files- a sem study

Background: Root canal preparations done using many rotary endodontic instruments results in formation of root dentin defects because of the stress induced by the instruments within the root canal during cleaning and shaping, thereby worsening the long term prognosis of the root canal treated teeth. Many rotary instruments are been globally studied for the purpose of generating a correct instrument for root canal preparation. Objective: To compare dentinal microcrack formation whilst using ProTaper Next file, HyFlex EDM file and Two Shape file system. Materials and methods: Thirty mandibular first molars were selected and were divided into three groups. ProTaper Next, HyFlex EDM and Two Shape files were used to prepare the mesial canals. Roots were then sectioned 3, 6 and 9 mm from the apex, and the cut surface was observed under scanning electron microscope (SEM) and checked for the presence of dentinal microcracks.