Related Experiment Video
Updated: Jul 18, 2026

Quantitative Hardness Measurement by Instrumented AFM-indentation
Published on: November 22, 2016
Vickers hardness investigation of work-hardening in used NiTi rotary instruments
Satish B Alapati1, William A Brantley, John M Nusstein
1Section of Oral Biology, College of Dentistry, The Ohio State University, Columbus, Ohio 43218-2357, USA.
Abstract:
A contributing mechanism for clinical failure of NiTi rotary instruments might be excessive work hardening. Vickers hardness was measured with 300 gm load near the flutes in three regions (D2-D4, D6-D10, and D14 towards the shank) for nine representative clinically used ProFile GT instruments that had been axially sectioned (10 measurements in each region). Consistent values could not be obtained at D1. Minimum hardness occurred at D2 to D4, with means from 313 to 324 (SD from 7 to 16). Maximum hardness with means ranging widely from 330 to 481 was found beyond D14. Mean hardness at D2 to D4 was 320 for an as-received ProFile instrument. Because a mean Vickers hardness of 326 has been reported for a shape-memory NiTi orthodontic wire product, it can be concluded that the NiTi instruments did not experience substantial work hardening at D2 to D4 during clinical use, in agreement with previous differential scanning calorimetric analyses.
Related Concept Videos
Mechanical Characteristics of Steel
The tension test is fundamental for determining tensile strength. In this test, a steel specimen is stretched using a gripping device until it breaks. The data collected during this test are used to...
Toughness and Hardness of Aggregate
Plastic Deformation in Circular Shafts

