Endodontic instruments after torsional failure: Nanoindentation test

Ahmed Jamleh, Alireza Sadr, Naoyuki Nomura, Arata Ebihara, Yoshio Yahata, Takao Hanawa, Junji Tagami, Hideaki Suda

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


This study aimed to evaluate effects of torsional loading on the mechanical properties of endodontic instruments using the nanoindentation technique. ProFile (PF; size 30, taper 04; Dentsply Maillefer, Switzerland) and stainless steel (SS; size 30, taper 02; Mani, Japan) instruments were subjected to torsional test. Nanoindentation was then performed adjacent to the edge of fracture (edge) and at the cutting part beside the shank (shank). Hardness and elastic modulus were measured under 100-mN force on 100 locations at each region, and compared to those obtained from the same regions on new instruments. It showed that PF and SS instruments failed at 559-±-67 and 596-±-73 rotation degrees and mean maximum torque of 0.90-±-0.07 and 0.99-±-0.05-N-cm, respectively. Hardness and elastic modulus ranged 4.8-6.7 and 118-339-GPa in SS, and 2.7-3.2 and 52-81-GPa in PF. Significant differences between torsion-fractured and new instruments in hardness and elastic modulus were detected in the SS system used. While in PF system, the edge region after torsional fracture had significantly lower hardness and elastic modulus compared to new instruments. The local hardness and modulus of elasticity of endodontic instruments adjacent to the fracture edge are significantly reduced by torsional loading.

Original languageEnglish
Pages (from-to)437-443
Number of pages7
Issue number4
Publication statusPublished - 2014


  • elastic modulus
  • hardness
  • nanoindentation
  • nickel-titanium
  • stainless steel


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