Year : 2020

Volume : Volume 11

Issue : Issue 2s

Address for correspondence :
Dr. Mrunalini Vaidya.
drmrunalvaidya@gmail.com

Abstract

Background:  To evaluate the effect of temperature of distilled water and sodium hypochlorite (NaOCl) on the cyclic fatigue resistance of two heat treated Ni-Ti rotary endodontic files in simulated clinical use. Materials and Method: A total of 80 new 2Shape and Neoendo flex were tested. Forty files of the same brand were randomly assigned to four groups (n = 10) and submitted to the following immersion protocol – distilled water at 20℃, distilled water at 37℃, sodium hypochlorite (NaOCl) at 20℃ and sodium hypochlorite at 37℃. Resistance to cyclic fatigue was calculated by counting the numbers of cycles to fracture in a simulated double curvature canal. Data were analysed by two-way analyses of variance.  Results: Resistance to cyclic fatigue of the Ni-Ti file was not significantly affected by immersion in NaOCl (P > .05).  The comparison between 2Shape and Neoendo flex files, when immersed in the same solution, did not show significant differences (P > .05). However, increasing the temperature up to 37℃ reduced the fatigue resistance. Conclusions: Under the conditions of this study, immersion in sodium hypochlorite at simulated body temperature was associated with a marked decrease in the cyclic fatigue resistance of all the rotary instruments tested in simulated clinical use.

Keywords: Cyclic fatigue, endodontic files, temperature.