Y. Haikel et al., MECHANICAL-PROPERTIES OF NICKEL-TITANIUM ENDODONTIC INSTRUMENTS AND THE EFFECT OF SODIUM-HYPOCHLORITE TREATMENT, Journal of endodontics, 24(11), 1998, pp. 731-735
The purpose of this study was to assess the mechanical properties-tors
ional moment, maximum angular deflection, maximum bending moment, and
permanent angular deflection - of four brands of nickel-titanium (NiTi
) endodontic file, and compare them with a conventional stainless-stee
l instrument, both in the presence and absence of sodium hypochlorite
(NaOCl). NiTi instruments from four manufacturers were randomly select
ed and subjected to NaOCl treatment for 12 or 48 h, or not at all. The
mechanical properties under test were then measured automatically by
a digital torque memocouple. Torsional moment and maximum angular defl
ection indicate the resistance to torsional fracture of an instrument,
maximum bending moment the stiffness of the instrument, and permanent
angular deflection the strength of the base alloy. All instruments ev
aluated complied with or exceeded ADA/ANSI Specification No. 28, with
the sole exception of the Maillefer ISO size 40 for torsional moment.
JS Dental and McSpadden NiTi files were the most resistant to torsiona
l fracture, but all NiTi files were inferior when compared with stainl
ess-steel files from a previous study. However, NiTi files were superi
or in flexibility, and Maillefer and Brasseler instruments were the be
st of the instruments tested. NiTi files also had negligible permanent
deformation angles. Furthermore, for all properties tested, NaOCl had
no statistically significant effect.