Ultrastructural analysis of the surface of endodontic instruments after immersion in irrigating solutions

Introduction Separation (fracture) of endodontic instruments in the root canal during chemomechanical instrumentation is a complication that can compromise the final outcome of endodontic treatment. One of the most common factors that cause fatigue of endodontic instruments and consequent fracture is surface corrosion. The aim of this study was to investigate the ultrastructure of surface corrosion of endodontic instruments made of stainless steel and nickel-titanium after immersion in the most commonly used root canal irrigants. Material and Methods The study included 48 nickel-titanium and stainless steel endodontic hand files. All instruments were immersed in 5.25% sodium hypochlorite, 0.2% CHX and 17% EDTA. Surface corrosion was analyzed using a scanning electron microscope (SEM). Results Nickel-titanium instruments showed significantly higher susceptibility to corrosion after immersion in 5.25% sodium hypochlorite compared to stainless steel instruments (p