New heat-treated vs electropolished nickel-titanium instruments used in root canal treatment: Influence of autoclave sterilization on surface roughness

Abstract

Nickel-titanium (NiTi) instruments used to treat root canal infections are affected by autoclave sterilization in various ways. The aim of this study was to compare the effect of autoclave sterilization on two NiTi rotary instruments that undergo different manufacturing treatments: The electro-polished Race and the heat-treated Race Evo, using scanning electron microscope analysis. In this in-vitro study, Race and Race-Evo instruments were subjected to a number of autoclaving cycles (0, 1, 3, 5, and 10). Scanning electron microscopy images were obtained at 3 mm from the tip of the file at 450x and 1000x magnifications. Surface roughness parameters were measured using ImageJ software. The results showed that autoclave sterilization caused a significant decrease in conventional NiTi Race surface roughness. While in Race Evo, surface roughness increased following the first autoclaving cycle. After 10 autoclaving cycles, surface roughness significantly decreased for both Race and Race Evo files.

Comprehensive Characterization of Blue Wire NiTi File Failure: A Comparative Analysis of Cyclic Fatigue and Torsional Resistance Properties

“…NaOCl is known to develop corrosive zones on the surface [2]. RE was not affected due to the presence of the blue titanium oxide layer, which is known to improve resistance to wear and decrease surface roughness with autoclave sterilization [13,15,32]. The negative effect of NaOCl on cyclic fatigue resistance was noticed in some NiTi systems, such as ProTaper Gold, EdgeTaper Platinum, and D-Race [2,33,34], but not in others (Wave One, Wave One Gold, and HyFlex EDM) [26,35,36].…”

Comparing the impact of various sterilization methods on the cyclic fatigue resistance, bending strength, and torsional fatigue properties of NiTi rotary files

“…The higher cyclic fatigue resistance of Race Evo file could be attributed to unique and distinctive heat treatment which enhances its flexibility and increased resilience against cyclic fatigue and fractures, and ability to operate at higher speed [20]. Additionally, the triangular cross-sectional geometry with an alternating cutting edge mitigate the screw effect and enhance precision during instrumentation [21]. Although, Tornado Blue file system claims a characteristic blue heat treatment for greater flexibility and torsional fatigue resistance [22].…”

Scanning Electron Microscopic Analysis of Deformation of TruNatomy File Systems: An Ex-vivo Study

“…However, sterilisation through autoclaving can lead to an increase in surface roughness values as the number of autoclaving cycles increases. A previous study documented increased surface degradations and reduced cutting efficiency in autoclaved file systems [ 26 ]. These degradations were more severe when the instruments were exposed to NaOCl and EDTA liquids sequentially after autoclaving [ 27 ].…”