Vickers Hardness Investigation of Work-Hardening in Used NiTi Rotary Instruments

Satish B. Alapati, William A. Brantley, John M. Nusstein, Glenn S. Daehn, Timothy A. Svec, John M. Powers, William M. Johnston, Wenhua Guo

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1191-1193
Number of pages3
JournalJournal of endodontics
Issue number12
StatePublished - Dec 2006

ASJC Scopus subject areas

  • Dentistry(all)


Dive into the research topics of 'Vickers Hardness Investigation of Work-Hardening in Used NiTi Rotary Instruments'. Together they form a unique fingerprint.

Cite this