A Review of Cyclic Fatigue Testing of Nickel-Titanium Rotary Instruments

Plotino, Gianluca; Grande, Nicola M.; Cordaro, Massimo; Testarelli, Luca; Gambarini, Gianluca

doi:10.1016/j.joen.2009.06.015

Cited by 332 publications

(346 citation statements)

References 52 publications

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“…Instrument fracture reportedly occurs as a result of two types: torsion and flexural fatigue 16) . Torsional fracture occurs when the torque resulted from the contact between the instrument and canal wall exceeds the torsional strength of the instrument, or when the instrument tip is locked in a canal whilst the rest continues to rotate.…”

Section: Introductionmentioning

confidence: 99%

“…In unused NiTi instruments, work hardening 19) and surface defects 20) have been reported. Although many studies have been conducted to compare the magnitude of cyclic fatigue in different NiTi instrument systems 16) , there has been a lack of evaluation of the dispersion of the number of cycles to fracture (NCF) under the same experimental conditions using a large number of identically shaped instruments. We aimed to determine the stochastic dispersion of the lifetime of NiTi instruments and evaluate the DL change during the cyclic fatigue test.…”

Section: Introductionmentioning

confidence: 99%

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Deflecting load of nickel titanium rotary instruments during cyclic fatigue

et al. 2012

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The dispersion of the lifetime of NiTi instruments, and their deflecting load (DL) changes during cyclic fatigue were investigated. A total of 120 ProFile NiTi rotary instruments were tested using a specially designed cyclic fatigue testing apparatus with three pins. Using these pins, the instrument was bent and rotated at 300 rpm to fracture. DL was recorded using a load cell attached to the central pin. For each sample, the working time was converted to number of cycles to fracture (NCF) and the mean DL (DLm) was calculated. The averages of NCF and DLm of 120 samples were 584.3±180.5 cycles and 6.44±0.91 N, respectively. All samples showed a sequential decrease in DL during rotation. Based on the present study, it is impossible to estimate the lifetime of a NiTi instrument from NCF. Thus, the change in DL could be an alternative criterion to determine the remaining lifetime.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deflecting load of nickel titanium rotary instruments during cyclic fatigue

et al. 2012

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“…Despite their undeniably favorable qualities, there is a potential risk of ''unexpected'' fracture with NiTi instruments (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Even though there have been considerable improvements in the file design and manufacturing methods on endodontic rotary instruments made of NiTi alloys, rotary instrument intracanal separation caused by cyclic fatigue remains a concern, especially in root canals with severe curvatures (11)(12)(13)(14)(15)(16). The mechanical behavior of NiTi alloy is determined by the relative proportions and characteristics of the microstructural phases.…”

mentioning

confidence: 99%

Current Challenges and Concepts of the Thermomechanical Treatment of Nickel-Titanium Instruments

Shen

Zhou

Zheng

et al. 2013

Journal of Endodontics

458

438

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Introduction: The performance and mechanical properties of nickel-titanium (NiTi) instruments are influenced by factors such as cross-section, flute design, raw material, and manufacturing processes. Many improvements have been proposed by manufacturers during the past decade to provide clinicians with safer and more efficient instruments. Methods: The mechanical performance of NiTi alloys is sensitive to their microstructure and associated thermomechanical treatment history. Heat treatment or thermal processing is one of the most fundamental approaches toward adjusting the transition temperature in NiTi alloy, which affects the fatigue resistance of NiTi endodontic files. The newly developed NiTi instruments made from controlled memory wire, M-Wire (Dentsply Tulsa Dental Specialties, Tulsa, OK), or R-phase wire represent the next generation of NiTi alloys with improved flexibility and fatigue resistance. The advantages of NiTi files for canal cleaning and shaping are decreased canal transportation and ledging, a reduced risk of file fracture, and faster and more efficient instrumentation. The clinician must understand the nature of different NiTi raw materials and their impact on instrument performance because many new instruments are introduced on a regular basis. Results: This review summarizes the metallurgical properties of next-generation NiTi instruments, the impact of thermomechanical treatment on instrument flexibility, and the resistance to cyclic fatigue and torsion. Conclusions: The aim of this review was to provide clinicians with the knowledge necessary for evidence-based practices, maximizing the benefits from the selection and application of NiTi rotary instruments for root canal treatment. (J Endod 2013;39:163-172)

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“…Due to the fact that the counterclockwise angle is greater than the clockwise one, it is claimed that the instrument continuously progresses toward the terminus of the root canal. Both instruments have been evaluated in preliminary studies 22,23,26,[28][29][30][31][32] and the results regarding lifespan, cyclic fatigue resistance, shaping ability and cleaning efficiency were satisfactory.…”

Section: 24mentioning

confidence: 99%

Cyclic Fatigue Resistance of Three Single-use NiTi Instruments after Immersion in Sodium Hypochlorite

Dagna¹,

Beltrami²,

Colombo³

et al. 2014

International Journal of Experimental Dental Science

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The aim of this in vitro study was to compare the cyclic fatigue resistance of three single-use nickel-titanium (NiTi) instruments (One Shape, Reciproc and Wave One) after immersion in sodium hypochlorite (NaOCl) solution over several time periods. A total of 135 One Shape, Reciproc R25 and Wave One Primary were tested. The 45 files of the same brand were randomly assigned to three groups (n = 15) and submitted to the following immersion protocol: 1 minute in 5% NaOCl at 37ºC, 5 minutes in 5% NaOCl at 37ºC, no immersion (as control). Cyclic fatigue test was performed rotating/reciprocating all instruments in a stainless steel curved artificial canal (60º angle of curvature and 5 mm radius). The number of cycles to fracture (NCF) was determined by measuring the time to fracture. The data were compared for differences by using 2-way analysis of variance (p < 0.05). In general, resistance to cyclic fatigue was not significantly affected by immersion in NaOCl. Reciproc R2 showed the highest cyclic fatigue resistance in all groups compared to One Shape and Wave One. Immersion in NaOCl for 1 or 5 minutes did not reduce the cyclic fatigue resistance of NiTi single-use instruments significantly. Reciproc were more resistant, but the new rotary single-use One Shape instruments showed mechanical resistance similar to NiTi files developed for reciprocating motion.

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A Review of Cyclic Fatigue Testing of Nickel-Titanium Rotary Instruments

Cited by 332 publications

References 52 publications

Deflecting load of nickel titanium rotary instruments during cyclic fatigue

Deflecting load of nickel titanium rotary instruments during cyclic fatigue

Current Challenges and Concepts of the Thermomechanical Treatment of Nickel-Titanium Instruments

Cyclic Fatigue Resistance of Three Single-use NiTi Instruments after Immersion in Sodium Hypochlorite

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