Impact of Heat Treatments on the Fatigue Resistance of Different Rotary Nickel-titanium Instruments

doi:10.1016/j.joen.2014.03.007

Journal of Endodontics

Volume 40, Issue 9, September 2014, Pages 1494-1497

https://doi.org/10.1016/j.joen.2014.03.007 Get rights and content

Abstract

Introduction

The aim of this study was to assess the influence of M-Wire (Dentsply Tulsa Dental Specialties, Tulsa, OK) and controlled memory technologies on the fatigue resistance of rotary nickel-titanium (NiTi) files by comparing files made using these 2 technologies with conventional NiTi files.

Methods

Files with a similar cross-sectional design and diameter were chosen for the study: new 30/.06 files of the EndoWave (EW; J. Morita Corp, Osaka, Japan), HyFlex (HF; Coltene/Whaledent, Inc, Cuyahoga Falls, OH), ProFile Vortex (PV; Dentsply Tulsa Dental Specialties, Tulsa, OK), and Typhoon (TYP; Clinician's Choice Dental Products, New Milford, CT) systems together with ProTaper Universal F2 instruments (PTU F2; Dentsply Maillefer, Ballaigues, Switzerland). The compositions and transformation temperatures of the instruments were analyzed using x-ray energy-dispersive spectroscopy and differential scanning calorimetry, whereas the mean file diameter values at 3 mm from the tip (D3) were measured using image analysis software. The average number of cycles to failure was determined using a fatigue test device.

Results

X-ray energy-dispersive spectroscopy analysis showed that, on average, all the instruments exhibited the same chemical composition, namely, 51% Ni–49% Ti. The PV, TYP, and HF files exhibited increased transformation temperatures. The PTU F2, PV, and TYP files had similar D3 values, which were less than those of the EW and HF files. The average number of cycles to failure values were 150% higher for the TYP files compared with the PV files and 390% higher for the HF files compared with the EW files.

Conclusions

M-Wire and controlled memory technologies increase the fatigue resistance of rotary NiTi files.

Section snippets

Materials and Methods

We evaluated new 30/.06 files of the EndoWave (EW; J. Morita Corp, Osaka, Japan), HF, PV, and TYP systems together with ProTaper Universal F2 instruments (PTU F2; Dentsply Maillefer, Ballaigues, Switzerland). These instruments were chosen because they have similar geometric designs; EW and HF exhibit triangular cross-sections, whereas PTU F2, PV, and TYP exhibit convex triangular cross-sections. However, these instruments use the following different technologies: EW and F2 are made of C-NiTi,

Results

The results of the semiquantitative x-ray energy-dispersive spectroscopy analysis showed that, on average, all of the instruments exhibited the same chemical composition, namely, 51% Ni–49% Ti. High amounts of oxygen were initially found on the HF and TYP files because of their thick oxide surface layers. When this layer was properly ground and the analysis was repeated, the average values of Ni and Ti were the same as those of the other instruments.

The transformation temperatures determined by

Discussion

This study evaluated the fatigue resistance of endodontic instruments that are manufactured using conventional NiTi, MW, and CM technology, considering their structural and geometric characteristics. As with other alloys, the mechanical behavior of NiTi alloys is determined by the relative proportions and characteristics of their microstructural phases. Thermal processing is 1 of the most fundamental approaches used to adjust the Ni content of the β-phase and, consequently, the transition

Acknowledgments

Supported in part by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), Belo Horizonte, MG, Brazil; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes), Brasília, DF, Brazil; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brasília, DF, Brazil; and Pró-Reitoria de Pesquisa da Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.

The authors deny any conflicts of interest related to this study.

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Micro–computed Tomographic Evaluation of the Shaping Ability of 3 Reciprocating Single-File Nickel-Titanium Systems on Single- and Double-Curved Root Canals
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We performed a micro–computed tomographic assessment of the preparation of moderately single- and double-curved root canals using 3 single-file reciprocating nickel-titanium systems: S1 Plus Standard (Sendoline, Täby, Sweden), WaveOne Gold Primary (Dentsply Sirona, Ballaigues, Switzerland), and Reciproc R25 (VDW, Munich, Germany).
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Citation Excerpt :
Previous works in the literature [6–9] have noted that heat treatments can be effective tools to improve the fatigue resistance of NiTi wires and endodontic files. Figueiredo et al., [10] and Bahia et al., [9] have suggested that this improvement is related to the crack branching through the martensite variants resultant from these treatments. In the present work, heat treatments were performed on an initially superelastic NiTi wire in a wide range of temperatures from 300 °C to 600 °C.
Known by their functional shape memory and superelastic properties, aligned with an excellent biocompatibility, near equiatomic NiTi alloys are vastly used as biomaterials. In various applications, such as endodontic files and cardiovascular stents, NiTi components are subjected to aggressive fatigue conditions, making fatigue resistance and mechanisms relevant to the materiaĺs development. In this context, heat treatments can be a powerful tool to improve the fatigue life and efforts have been made to understand and predict the fatigue behavior of these alloys in different conditions. In this work, initially superelastic near equiatomic Ni-rich wires were heat-treated at 400 °C and 450 °C and the ε × Nf curve was obtained. Rotating-bending strain-controlled fatigue tests were performed at maximum strains varying from 1% to 5% at 37 °C. The results showed that both samples exhibited large fatigue resistance and similar fatigue behavior through the different maximum strains, and thus, treatments within the range of temperature from 400 °C to 450 °C are recommended to obtain NiTi components with high fatigue life for large maximum strain amplitudes.
Effects of aging treatments on the fatigue resistance of superelastic NiTi wires
2019, Materials Science and Engineering: A
Thermomechanical and aging treatments can be powerful tools to improve the fatigue life of NiTi wires submitted to severe conditions of cyclic deformation. In this work, aging treatments were performed in an initially superelastic NiTi wire in temperatures ranging from 300^oC until 600^oC for 30 min. The as-received and heat-treated wires’ microstructures were characterized by XRD, the transformation temperatures were obtained by DSC and the mechanical characterization was performed in tensile tests. The wires were then submitted to low-cycle fatigue tests in a rotating-bending machine at a maximum strain of 4%. The heat treatments were effective on improving the fatigue resistance, especially when the R-phase was formed. The highest number of cycles to failure was obtained in the samples heat treated at 400^oC and 450^oC.
Microtomographic Assessment of the Shaping Ability of the Hyflex CM and XP-endo Shaper Systems in Curved Root Canals
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2023, General Dentistry

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Basic ResearchImpact of Heat Treatments on the Fatigue Resistance of Different Rotary Nickel-titanium Instruments

Abstract

Introduction

Methods

Results

Conclusions

Section snippets

Materials and Methods

Results

Discussion

Acknowledgments

J Endod

J Endod

J Endod

J Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

Basic Research
Impact of Heat Treatments on the Fatigue Resistance of Different Rotary Nickel-titanium Instruments