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Physical and mechanical properties of twisted or ground nickel–titanium instruments
Author(s) -
Braga L. C.,
Magalhães R. R. S.,
Nakagawa R. K. L.,
Puente C. G.,
Buono V. T. L.,
Bahia M. G. A.
Publication year - 2013
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/iej.12011
Subject(s) - materials science , nickel titanium , nickel , titanium , metallurgy , shape memory alloy
Aim To compare the flexibility, torsional resistance and structural and dimensional characteristics of instruments produced by twisting with those of a geometrically similar nickel–titanium ( N i T i) system produced by a grinding process. Methodology The mean diameters along the flute and the pitch length of size 25, .04 taper, size 25, .06 taper, and size 25, .08 taper T wisted F ile ( TF ) ( S ybronEndo, Orange, CA , USA ), and size 25, .04 taper, and size 25, .06 taper R a C e instruments ( FKG , La Chaux‐de‐Fonds, S witzerland) ( n = 10 each) were measured according to ANSI / ADA specification N o. 101. Two pairs of instruments were found to have similar diameters at 3 mm from the tip: TF size 25, .06 taper and R a C e size 25, .04 taper, and TF size 25, .08 taper and R a C e size 25, .06 taper. The cross‐sectional areas at 3 mm from the tip were determined. These instruments were then submitted to energy‐dispersive X ‐ray spectroscopy, X ‐ray diffraction, differential scanning calorimetry ( DSC ), and V ickers microhardness measurements. Bending moment at 45° and maximum torque at fracture were measured ( n = 10) according to specification ISO 3630‐1. Data were analysed using analysis of variance (α = 0.05). Results The two types of instruments had approximately the same chemical composition, phase constitution, and austenite finishing temperatures. TF instruments had significantly ( P ≤ 0.001) lower V ickers microhardness values and were more flexible than R a C e instruments ( P = 0.016), but had similar ( TF size 25, .08 taper and R a C e size 25, .06 taper, P = 0.916) or significantly higher ( TF size 25, .06 taper and R a C e size 25, .04 taper, P ≤ 0.001) torsional resistance. Conclusions Comparison of TF and R a C e instruments of similar measured dimensions revealed that the different manufacturing methods employed for producing these instruments gave rise to different mechanical behaviours.