Defects in Nickel-Titanium Instruments after Clinical Use. Part 2: Fractographic Analysis of Fractured Surface in a Cohort Study

Shen, Ya; Cheung, Gary; Peng, Bin; Haapasalo, Markus

doi:10.1016/j.joen.2008.10.013

Cited by 81 publications

(79 citation statements)

References 32 publications

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“…In the present study, two instruments showed metal losses after 60 s of use and suffered fractures after 300 s of use. These results are in agreement with Svec and Powers' [23] observations of metal losses from the cutting angles of ProFile flutes and deformations after just one use, as well as Shen and colleagues' [24][25] reports indicating that the propagation of previous cracks and defects may explain instrument fracture.…”

Section: Discussionsupporting

confidence: 90%

Morphological alterations of rotary nickel-titanium protaper® instruments analyzed by SEM: effect of nitrogen ion implantation

Becker

Oliveira

Hinrichs

et al. 2015

Rev. Odonto Ciênc. (Online)

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Objective: To analyze, using scanning electron microscopy [SEM], the morphological changes [distortion, loss of substance, and fracture] of ProTaper SX rotary instruments submitted to nitrogen ion implantation. Methods: Thirty ProTaper SX Instruments were divided into 3 groups of 10 instruments each. Groups A and B were subjected to ionic implantation with bands of nitrogen ions at 100 kV [group A] or 200 kV [group B] and an ion dose of 1.0×10 17 ions/cm². Instruments in group C served as unmodified controls. Each instrument was utilized to prepare 5 canals in epoxy resin blocks with a brushing motion. Instruments were examined by SEM before use and after 60 s and 300 s of work inside canals in epoxy resin blocks. Results: No significant morphologic alterations were observed between the groups of instruments after preparation of the simulated canals. However, whereas only 1 instrument in group A and 1 instrument in group B fractured during use, 3 instruments in group C fractured during use. Conclusion: Ionic implantation of nitrogen ions moderately improved the performance of SX files. Instruments treated by ionic implantation at either dose yielded better results than the untreated control group, although the differences were not significant.

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Section: Discussionsupporting

confidence: 90%

Morphological alterations of rotary nickel-titanium protaper® instruments analyzed by SEM: effect of nitrogen ion implantation

Becker

Oliveira

Hinrichs

et al. 2015

Rev. Odonto Ciênc. (Online)

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“…It allows to discard NiTi instruments which have accumulated metal fatigue, reducing the risk of unexpected breakage. Shen et al (29) showed that the tendency to show plastic deformation can vary amongst instruments, focusing the attention mainly on differences in design and not on the alloy or manufacturing process TFA instruments were also selected because of their unique motion, which has never been investigated in relation with clinical resistance to torsional and flexural fatigue. The present study also demonstrated that increasing coronal flaring allowed a safer progression to the working length of the instrument used immediately after.…”

Section: Discussionmentioning

confidence: 99%

Deformations and cyclic fatigue resistance of nickel-titanium instruments inside a sequence

Gambarini

Plotino

Piasecki³

et al. 2015

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SummaryAim. To compare the effect of brushing motion on torsional and cyclic fatigue resistance of TF Adaptive instruments after clinical use. Methods. 20 packs of TFA small sequence (SybronEndo, Orange, CA, USA) were used for this study and divided into two groups. Each instrument prepared one resin tooth, consisting in 4 canals with a complex anatomy. In group A, no brushing motion was performed. In group B, after the green instrument reached the working length, brushing motion with circumferential filing was performed for 15 seconds in each canal (overall 1 minute). All the instruments were then subjected to cyclic fatigue test and mean values and standard deviation for time to fracture were evaluated. Data were subjected to one-way analysis of variance and Bonferroni t-test procedure with a significance set at P < 0.05. Results. No instruments were broken during preparation of root canals. Two TF Adaptive green and 5 yellow showed unwinding after intracanal clinical use. No statistically significant differences were found between green instruments of both groups (P > 0.05), while a statistically significant difference was found between the yellow instruments (P < 0.05), with group B showing an higher resistance to cyclic fatigue. Conclusions. A prolonged passive brushing motion did not adversely affected mechanical resistance of the instrument used for this purpose. Resistance to both deformations and cyclic fatigue of the second instrument within the TFA small sequence was enhanced by the coronal flaring provided by the brushing action of the first instrument used.

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“…Thus, an instrument needs to be resistant to cyclic fatigue and have sufficient flexibility to permit the preparation of curved systems but also sufficient torque strength so that instrument separation does not occur. Fatigue has been implicated as the main reason for the fracture of endodontic rotary files used clinically (11,14).…”

Section: Mechanical Performance Of Thermomechanically-treated Niti Inmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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

Shen

Zhou

Zheng

et al. 2013

Journal of Endodontics

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451

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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Defects in Nickel-Titanium Instruments after Clinical Use. Part 2: Fractographic Analysis of Fractured Surface in a Cohort Study

Cited by 81 publications

References 32 publications

Morphological alterations of rotary nickel-titanium protaper® instruments analyzed by SEM: effect of nitrogen ion implantation

Morphological alterations of rotary nickel-titanium protaper® instruments analyzed by SEM: effect of nitrogen ion implantation

Deformations and cyclic fatigue resistance of nickel-titanium instruments inside a sequence

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

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