Physical and mechanical properties of twisted or ground nickel-titanium instruments.

Autor: Braga LC; Department of Restoration Dentistry, Faculty of Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil., Magalhães RR, Nakagawa RK, Puente CG, Buono VT, Bahia MG
Jazyk: angličtina
Zdroj: International endodontic journal [Int Endod J] 2013 May; Vol. 46 (5), pp. 458-65. Date of Electronic Publication: 2012 Oct 18.
DOI: 10.1111/iej.12011
Abstrakt: 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 (NiTi) 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 Twisted File (TF) (SybronEndo, Orange, CA, USA), and size 25, .04 taper, and size 25, .06 taper RaCe instruments (FKG, La Chaux-de-Fonds, Switzerland) (n = 10 each) were measured according to ANSI/ADA specification No. 101. Two pairs of instruments were found to have similar diameters at 3 mm from the tip: TF size 25, .06 taper and RaCe size 25, .04 taper, and TF size 25, .08 taper and RaCe 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 Vickers 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 Vickers microhardness values and were more flexible than RaCe instruments (P = 0.016), but had similar (TF size 25, .08 taper and RaCe size 25, .06 taper, P = 0.916) or significantly higher (TF size 25, .06 taper and RaCe size 25, .04 taper, P ≤ 0.001) torsional resistance.
Conclusions: Comparison of TF and RaCe instruments of similar measured dimensions revealed that the different manufacturing methods employed for producing these instruments gave rise to different mechanical behaviours.
(© 2012 International Endodontic Journal.)
Databáze: MEDLINE
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