Phase transformation behaviour and bending property of twisted nickel-titanium endodontic instruments

Hou, Xiaomei; Yahata, Yoshio; Hayashi, Y.; Ebihara, Arata; Hanawa, Takao; Suda, Hiroshi

doi:10.1111/j.1365-2591.2010.01818.x

Cited by 83 publications

(83 citation statements)

References 34 publications

(79 reference statements)

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“…1,7,11 The shaping ability of these instruments could be related to the difference in manufacturing method, which consists of twisting the metal and special surface conditioning to provide increased flexibility and fracture resistance 23 Gergi et al 7 and Marzouk and Ghoneim 2 also reported that using 0.08 taper of TF to full WL did not result in any severe aberrations in the apical portion. Therefore, according to Marzouk and Ghoneim, 2 the improved results of canal transportation with TF compared to single file reciprocating systems may be due to using lower tapered files prior to using a 0.08 tapered file.…”

Section: Discussionmentioning

confidence: 99%

Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

et al. 2015

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The endodontic preparation of curved and narrow root canals is challenging, with a tendency for the prepared canal to deviate away from its natural axis. The aim of this study was to evaluate, by cone-beam computed tomography, the transportation and centering ability of curved mesiobuccal canals in maxillary molars after biomechanical preparation with different nickel-titanium (NiTi) rotary systems. Forty teeth with angles of curvature ranging from 20° to 40° and radii between 5.0 mm and 10.0 mm were selected and assigned into four groups (n = 10), according to the biomechanical preparative system used: Hero 642 (HR), Liberator (LB), ProTaper (PT), and Twisted File (TF). The specimens were inserted into an acrylic device and scanned with computed tomography prior to, and following, instrumentation at 3, 6 and 9 mm from the root apex. The canal degree of transportation and centering ability were calculated and analyzed using one-way ANOVA and Tukey's tests (α = 0.05). The results demonstrated no significant difference (p > 0.05) in shaping ability among the rotary systems. The mean canal transportation was: -0.049 ± 0.083 mm (HR); -0.004 ± 0.044 mm (LB); -0.003 ± 0.064 mm (PT); -0.021 ± 0.064 mm (TF). The mean canal centering ability was: -0.093 ± 0.147 mm (HR); -0.001 ± 0.100 mm (LB); -0.002 ± 0.134 mm (PT); -0.033 ± 0.133 mm (TF). Also, there was no significant difference among the root segments (p > 0.05). It was concluded that the Hero 642, Liberator, ProTaper, and Twisted File rotary systems could be safely used in curved canal instrumentation, resulting in satisfactory preservation of the original canal shape.

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Section: Discussionmentioning

confidence: 99%

Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

et al. 2015

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“…This proprietary technology was used to optimize the phase constituents and properties of TF NiTi files (48). The 2-step transformation through an apparent R-phase can be observed for TFs in DSC curves (43,44).…”

Section: Metallurgical Characterization Of Thermomechanically-treatedmentioning

confidence: 99%

“…The properties of the bulk materials are the main determinant of fatigue life (35)(36)(37)(38)(39)(40)(41)(42) (42)(43)(44)(45). The conventional SE NiTi file has an austenite structure (26,(42)(43)(44)(45)(46), whereas NiTi file with thermal processing (eg, TYP CM and Vortex) would essentially be in the martensite condition at body temperature (42,44,45,47). In addition, the critical stress for martensite reorientation of CM Wires is in the range of 128-251 MPa at room temperature and 37 C, which is much lower than the critical stress for stress-induced martensite transformation of the SE wires (490-582 MPa) (42).…”

Section: Metallurgical Characterization Of Thermomechanically-treatedmentioning

confidence: 99%

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

Shen

Zhou

Zheng

et al. 2013

Journal of Endodontics

416

415

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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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“…The plateaus and hysteresis regarding the superelastic NiTi were not observed once these properties are mainly associated with phase transformation (Fernandes et al, 2011;Frenzel et al, 2010;Kim and Daly, 2011;Hou et al, 2011) which does not occur in FRC material. The figure 2 and table 1 demonstrated that FRC wires could cover the range of strength corresponding to the Ni-Ti wires under a deflection of 1.5 mm.…”

Section: Discussionmentioning

confidence: 99%

Failure of Fiber Reinforced Composite Archwires

Scabell¹,

Elias²,

Fernandes³

et al. 2013

DENT

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The objective of this article is to investigate the mechanical properties and surface morphology of fiber-reinforced composite (FRC) wires. FRC (Optis) wire and a NiTi 0.016 in diameter were evaluated with a 3-point bending test on a universal testing machine at temperatures of 23±1oC and 37±1oC. The sample was cut to a size of 30mm and divided into 5 groups, each consisting of 6 specimens. Group 1, 2 and 5 were tested at 3.1-mm deflection, groups 3 and 4 at 1.5mm deflection. The hysteresis curves were compared and the surface morphology of the FRC wires was observed by SEM. Clear breakages occurred between fibers and Polymethylmethacrylate (PMMA) matrix union between 1.5-mm and 2.0-mm deflection. Before 1.5-mm, the wires showed no significant changes in their surface structure. The flexural load required to produce a deflection of 1.5 mm on NiTi was near double that for the FRC wires. ANOVA indicated differences (P<.001) except between Optis groups 1, 3 and 5 (P>.05). FRC wires displayed comparable load-deflection curves to NiTi until deflection of 2.0mm, whereas it could be considered a viable alternative to metallic wires during mild irregular alignment situations. Failure occurs due to fibers pullout and breakage at the fiber/composite matrix interface.

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Phase transformation behaviour and bending property of twisted nickel-titanium endodontic instruments

Abstract: The new method of manufacturing NiTi instruments by twisting coupled with heat treatment might contribute to the increased phase transformation temperatures and superior flexibility.

Cited by 83 publications

References 34 publications

Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

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

Failure of Fiber Reinforced Composite Archwires

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