Comparison of distortion and separation utilizing profile and Pow-R nickel-titanium rotary files

The purpose of this study was to determine whether there was a difference i n the frequency of file distortion and separation between nickel-titanium ( Ni-Ti) ProFile 0.04 ISO taper rotary files and Ni-Ti Pow-R 0.04 ISO taper r otary files. For this study, 60 mesial root canals in 30 human mandibular f irst molars were chosen with the curvature angle of the mesiobuccal and mes iolingual canals of the same tooth within five degrees. ProFile and Pow-R f iles were randomly assigned to either the mesiobuccal or mesiolingual canal of the same tooth. Instrumentation proceeded per the manufacturer's recomm endations, in a crown-down technique, using Gates Glidden burs and rotary f iles in sizes #50 to #20. Positive and negative controls were used. The ins truments were evaluated for signs of distortion or separation by three inde pendent evaluators using magnification under microscope. A total of 420 fil es were evaluated, 210 files for Pow-R and 210 files for ProFile. There was no statistically significant difference in the incidence of instrument dis tortion or separation between the two file systems that were studied.