Comparative evaluation of the effects of multiple autoclaving on cyclic fatigue resistance of three different rotary Ni-Ti instruments: An in vitro study

Abstract

Aims:The aim of this in vitro study was to evaluate comparatively the effects of multiple autoclaving on surface topography and cyclic fatigue of three different rotary nickel-titanium (Ni-Ti) instruments.Materials and Methods:Twenty-one files each of Twisted Files (TF), Revo-S, and RaCe were used in this study. They were grouped as group 1-TF, group 2-Revo-S, and group 3-RaCe. All the files were autoclaved and subjected for scanning electron microscopic analysis and cyclic fatigue analysis.Results:Data were subjected to statistical analysis using one way analysis of variance (ANOVA) and post hoc Tukey's Kramer multiple comparison test. TF exhibited the highest cyclic fatigue resistance followed by Revo-S and RaCe. Scanning electron photomicrographs showed no obvious surface changes in the files after three autoclaving cycles.Conclusions:Within the limitation of this study, it can be concluded that Twisted Files was the most fatigue resistant compared to Revo-S and RaCe, and multiple autoclaving cycles did not have any significant alterations in the cyclic fatigue resistance of rotary Ni-Ti files.

Stereomicroscopic evaluation of defects caused by torsional fatigue in used hand and rotary nickel-titanium instruments

“…[ 21 ] The forces experienced by the files are correlated with the contact areas of friction between the instrument, the root canal wall, and the load required to cut the dentin. [ 22 ] Thus Protaper Universal rotary files require higher torque, making them more prone to metal fatigue[ 23 ] compared to fifth-generation Revo-S files, which have asymmetrical cross sections and a swaggering (snakelike) motion that allows easy escape of debris and prevents clogging[ 6 24 ] [ Figure 2 ]. Reduction of the contact length of the blade to the dentin and reduction of stress in Revo-S may have contributed to fewer defects compared to Protaper Universal.…”

“…Such a fatigue mechanism initiates microscopically within the elastic limit of metal, therefore it is not visible by visual inspection with the naked eyes. [ 1 5 6 7 ]…”

“…[ 9 ] Static torsional fatigue: Occurs due to continuous rotation of the file at one end while the other end stops spinning, i.e., when the tip or a part of file binds in the root canal and handpiece that holds the shank of the file and continues to rotate, it leads to torsional failure. [ 1 6 7 9 ] …”

An analysis of cyclic fatigue resistance of reciprocating instruments in different canal curvatures after immersion in sodium hypochlorite and autoclaving: An in vitro study

“…[ 10 ] This can be explained by the overloading induced on the instrument by an abrupt change in canal curvature which restrains the rotating instrument, giving rise to multidirectional loading (tension, bending, and torsion) that leads to ductile fracture. [ 11 ]…”

Erratum

“…In the article that appeared on page 323 of July-August 2013 issue of Journal of Conservative Dentistry. Author sequence was given as “Kanthimathinathan Meenakshi Sundaram, Rajesh AV Ebenezar, Mohamed Fayas Ghani, Leena Martina, Ashwin Narayanan, Bejoy Mony[ 1 ]” along with its affiliation as “ Department of Conservative Dentistry & Endodontics, SRM Dental College & Hospital, SRM University, Chennai, 1 Annoor Dental College, Kerala, India” ,…”