Mechanical Properties of Various Heat-treated Nickel-titanium Rotary Instruments

This study compared the torsional resistance of heat-treated nickel-titanium (NiTi) instruments under different temperature conditions. Four thermomechanically treated single-use NiTi rotary instruments were selected for this study: OneShape (OS), OneCurve (OC), WaveOne Gold (WOG) and HyFlex EDM (HFE). Each instrument was further subdivided by temperature into 2 subgroups. Maximum torque and the distortion angle until fracture occurred were evaluated. Differential scanning calorimetry analysis was performed to measure the phase transformation temperature. Statistical analysis was performed using a two-way ANOVA and t-test (p < 0.05). Fractured fragments were observed using scanning electron microscopy (SEM). The two-way ANOVA showed no significant differences for different temperature conditions. At both room (RT) and body temperature (BT), OS was predominantly austenite while HFE was martensite. OC and WOG were predominantly martensite at RT and mixed phase at BT. At BT, more than half of WOG was martensite, while half of OC was austenite. SEM examination showed no topographical differences between instruments in different temperature groups. In relation to a limitation of this study, there was no difference in torsional resistance of NiTi rotary instruments between the BT and RT conditions. This implies that clinicians do not need to consider a decrease of torsional resistance of heat-treated NiTi instruments at BT.

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Influence of Electrochemical Polishing on the Mechanical Properties of K3 Nickel-Titanium Rotary Instruments

Journal of Endodontics ◽

10.1016/j.joen.2008.08.023 ◽

2008 ◽

Vol 34 (12) ◽

pp. 1533-1536 ◽

Cited By ~ 13

Author(s):

Fabiola Ormiga Galvão Barbosa ◽

José Antônio da Cunha Ponciano Gomes ◽

Marcos Cesar Pimenta de Araújo

Keyword(s):

Mechanical Properties ◽

Nickel Titanium ◽

Electrochemical Polishing ◽

Rotary Instruments

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Mechanical properties of nickel-titanium rotary instruments produced with a new manufacturing technique

International Endodontic Journal ◽

10.1111/j.1365-2591.2010.01835.x ◽

2011 ◽

Vol 44 (4) ◽

pp. 337-341 ◽

Cited By ~ 64

Author(s):

G. Gambarini ◽

G. Plotino ◽

N. M. Grande ◽

D. Al-Sudani ◽

M. De Luca ◽

...

Keyword(s):

Mechanical Properties ◽

Nickel Titanium ◽

Manufacturing Technique ◽

Rotary Instruments

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Comparison of the Mechanical Properties of Rotary Instruments Made of Conventional Nickel-Titanium Wire, M-Wire, or Nickel-Titanium Alloy in R-Phase

Journal of Endodontics ◽

10.1016/j.joen.2012.12.006 ◽

2013 ◽

Vol 39 (4) ◽

pp. 516-520 ◽

Cited By ~ 55

Author(s):

Hélio P. Lopes ◽

Thaiane Gambarra-Soares ◽

Carlos N. Elias ◽

José F. Siqueira ◽

Inês F.J. Inojosa ◽

...

Keyword(s):

Mechanical Properties ◽

Titanium Alloy ◽

Nickel Titanium ◽

Rotary Instruments ◽

Titanium Wire

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Nickel–Titanium Rotary Instruments: An In Vitro Comparison (Torsional Resistance of Two Heat-treated Reciprocating Files)

The Journal of Contemporary Dental Practice ◽

10.5005/jp-journals-10024-3081 ◽

2021 ◽

Vol 22 (4) ◽

pp. 361-364

Author(s):

Shilpa Bhandi ◽

Gianluca Gambarini ◽

Marco Seracchiani ◽

Luca Testarelli ◽

Alessandro Mazzoni ◽

...

Keyword(s):

Nickel Titanium ◽

Torsional Resistance ◽

Heat Treated ◽

Rotary Instruments ◽

In Vitro Comparison

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An Update on Nickel-Titanium Rotary Instruments in Endodontics: Mechanical Characteristics, Testing and Future Perspective—An Overview

Bioengineering ◽

10.3390/bioengineering8120218 ◽

2021 ◽

Vol 8 (12) ◽

pp. 218

Author(s):

Alessio Zanza ◽

Maurilio D’Angelo ◽

Rodolfo Reda ◽

Gianluca Gambarini ◽

Luca Testarelli ◽

...

Keyword(s):

Mechanical Properties ◽

Titanium Alloy ◽

Mechanical Characteristics ◽

State Of The Art ◽

Cyclic Fatigue ◽

Nickel Titanium ◽

Future Perspective ◽

Current State ◽

Rotary Instruments ◽

Torsional Loads

Since the introduction of Nickel-Titanium alloy as the material of choice for the manufacturing of endodontic rotary instruments, the success rate of the root canal therapies has been significantly increased. This success mainly arises from the properties of the Nickel-Titanium alloy: the biocompatibility, the superelasticity and the shape memory effect. Those characteristics have led to a reduction in time of endodontic treatments, a simplification of instrumentation procedures and an increase of predictability and effectiveness of endodontic treatments. Nevertheless, the intracanal separation of Nickel-Titanium rotary instruments is still a major concern of endodontists, with a consequent possible reduction in the outcome rate. As thoroughly demonstrated, the two main causes of intracanal separation of endodontic instruments are the cyclic fatigue and the torsional loads. As results, in order to reduce the percentage of intracanal separation research and manufacturers have been focused on the parameters that directly or indirectly influence mechanical properties of endodontic rotary instruments. This review describes the current state of the art regarding the Nickel-Titanium alloy in endodontics, the mechanical behavior of endodontic rotary instruments and the relative stresses acting on them during intracanal instrumentation, highlighting the limitation of the current literature.

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Role of the Flat-Designed Surface in Improving the Cyclic Fatigue Resistance of Endodontic NiTi Rotary Instruments

Materials ◽

10.3390/ma12162523 ◽

2019 ◽

Vol 12 (16) ◽

pp. 2523 ◽

Cited By ~ 6

Author(s):

Gianluca Gambarini ◽

Gabriele Miccoli ◽

Marco Seracchiani ◽

Tatyana Khrenova ◽

Orlando Donfrancesco ◽

...

Keyword(s):

Cyclic Fatigue ◽

Nickel Titanium ◽

Segment Length ◽

Flat Side ◽

Heat Treated ◽

Rotary Instruments ◽

Time To Fracture ◽

Niti Instruments ◽

Niti Rotary Instruments

The aim of this study was to investigate the role of the flat-designed surface in improving the resistance to cyclic fatigue by comparing heat-treated F-One (Fanta Dental, Shanghai, China) nickel–titanium (NiTi) rotary instruments and similar prototypes, differing only by the absence of the flat side. The null hypothesis was that there were no differences between the two tested instruments in terms of cyclic fatigue lifespan. A total of 40 new NiTi instruments (20 F-One and 20 prototypes) were tested in the present study. The instruments were rotated with the same speed (500 rpm) and torque (2 N) using an endodontic motor (Elements Motor, Kerr, Orange, CA, USA) in the same stainless steel, artificial canal (90° angle of curvature and 5 mm radius). A Wilcoxon–Mann–Whitney test was performed to assess the differences in terms of time to fracture and the length of the fractured segment between the flat- and non-flat-sided instruments. Significance was set at p = 0.05. The differences in terms of time to fracture between non-flat and flat were statistically significant (p < 0.001). In addition, the differences in terms of fractured segment length were statistically significant (p = 0.034). The results of this study highlight the importance of flat-sided design in increasing the cyclic fatigue lifespan of NiTi rotary instruments.

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