Morphological alterations of rotary nickel-titanium protaper® instruments analyzed by SEM: effect of nitrogen ion implantation

Abstract

Objective: To analyze, using scanning electron microscopy [SEM], the morphological changes [distortion, loss of substance, and fracture] of ProTaper SX rotary instruments submitted to nitrogen ion implantation. Methods: Thirty ProTaper SX Instruments were divided into 3 groups of 10 instruments each. Groups A and B were subjected to ionic implantation with bands of nitrogen ions at 100 kV [group A] or 200 kV [group B] and an ion dose of 1.0×10 17 ions/cm². Instruments in group C served as unmodified controls. Each instrument was utilized to prepare 5 canals in epoxy resin blocks with a brushing motion. Instruments were examined by SEM before use and after 60 s and 300 s of work inside canals in epoxy resin blocks. Results: No significant morphologic alterations were observed between the groups of instruments after preparation of the simulated canals. However, whereas only 1 instrument in group A and 1 instrument in group B fractured during use, 3 instruments in group C fractured during use. Conclusion: Ionic implantation of nitrogen ions moderately improved the performance of SX files. Instruments treated by ionic implantation at either dose yielded better results than the untreated control group, although the differences were not significant.