EVALUATION OF SURFACE CHANGES IN PROTAPER UNIVERSAL ROTARY FILES AFTER SINGLE AND MULTIPLE USES IN SEMI CURVED CANALS WITH DIFFERENT IRRIGATING SOLUTIONS: A SEM ANALYSIS

Abstract

NiTi files fracture due to fatigue failure which occurs after mechanical degradation of files. ProTaper rotary instruments are claimed to generate lower torque values during the use. The corrosion on the surface of Protaper files as a result of chemical reactions of irrigants causes different defects and may lead early fracture. So the present study was undertaken to evaluate surface changes in ProTaper files after multiple uses in semi curved canals in conjugation with three different irrigants. ProTaper files were used to instrument extracted premolars and molars with three different irrigants. These files are then subjected to SEM analysis to evaluate different topographical defects. It was found to be that in NaOCl group 60% of the files did not show any defect after single use where as 85 % of the files show fracture and micro cracks after multiple canals in NaOCl group. In Chlorohexidine group 40% files did not show any defect after single use whereas all of the files show defect after multiple use with equal distribution of micro cracks, distortion and disruption of cutting edges. Similar distribution of defects has been seen with EDTA group.
Keywords:  ProTaper Universal rotary files, single and multiple use, scanning electron microscope