1038 Corrosion Properties of Contemporary Nickel-Titanium Endodontic Files

Friday, March 23, 2012: 3:30 p.m. - 4:45 p.m.
Presentation Type: Poster Session
D.W. BERZINS, A.C. BARNES, and N.D. VASSILIADES, Marquette University, Milwaukee, WI

Several years ago, a few endodontic instrument manufacturers developed nickel-titanium (NiTi) files (Twisted File and GTX) made with proprietary processes beyond those used for conventional NiTi files. This trend has continued with the introduction of shape-memory NiTi files (Berzins 2011 IADR#1710). Resistance to chemical dissolution is important in endodontic files since the conjoint factors of stress and corrosion may limit the fatigue life of rotary instruments.


Objectives: The objective of this study was to evaluate the corrosion properties of two conventionally-manufactured superelastic NiTi files (ProFile and K3), two newer superelastic NiTi files manufactured with proprietary treatments (Twisted File and GTX), and two shape-memory NiTi files (CM wire and HyFlex).

Methods: Six endodontic files were investigated: Twisted File and K3 (SybronEndo), ProFile and GTX (Dentsply Tulsa Dental), CM Wire (DS Dental), and HyFlex (Coltene-Whaledent). All files (n=8/brand) were size 40 with a .04 taper. The distal 12 mm of the files was isolated and electrochemically tested in 2.5% sodium hypochlorite (NaOCl) at 35oC. The open circuit potential (OCP) was monitored for 1 hr followed by polarization resistance and cyclic polarization tests. OCP at 1 hr and log transformed corrosion current (Icorr) were compared using ANOVA/Tukey (p<0.05).

Results: The enclosed table displays the electrochemical results (mean standard deviation).


OCP (mV vs. SCE)

Icorr (nA)


57711 A

2030580 C


343139 B

7354 A

Twisted File

36893 B

6728 A


57432 A

370270 B

CM Wire

-165 C

115004700 D


-10488 C

440720 AB

Different letters denote a significant difference (p<0.05) between files within each parameter. Shape memory files exhibited decreased nobility. In terms of corrosion rate (Icorr), over 100-fold differences were observed between files.

Conclusion: Extreme differences in corrosion properties exist among NiTi endodontic rotary files.

Keywords: Alloys, Corrosion, Endodontics, Metals and Physical