Wear resistance of cryogenically treated stainless steel files

Cryogenic treatment, which involves ultra-subzero treatment of metal alloys , has been shown to improve the wear resistance of several types of stainle ss steel. The purpose of this study was to examine the effect of cryogenic treatment on wear resistance of Flex-R and Hedstrom (Union Broach) files. T hese instruments were attached to an Instron testing machine and underwent 300 push-pull strokes (6-mm movement range, 600-mm/min speed, 1-N loading) against 1.5-mm thick dentin wafers. Their wear was determined by comparing the depth of grooves (without changing file position) cut in acrylic specim ens (1.5-mm thick) before and after machining dentin. The mean and standard deviation (n = 20) of the relative change in cutting efficiency was determ ined for the files. An analysis of variance showed that the cutting efficie ncy of all files decreased significantly after wearing on dentin (p < 0.000 1). However, when comparing the post-/pre-cutting efficiency ratios of the files, it was seen that cryogenic treatment did not affect the wear resista nce of the files.