Effect of canal curvature location on the cyclic fatigue resistance of reciprocating files

Sobotkiewicz, Tyler; Huang, Xiangya; Haapasalo, Markus; Mobuchon, Christophe; Hieawy, Ahmed; Hu, Jinghao; Zhou, Huimin; Wang, Zhejun; Shen, Ya

doi:10.1007/s00784-020-03348-8

Cited by 11 publications

(10 citation statements)

References 33 publications

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“…The results showed that apical curvatures led to higher NCF compared with middle and coronal curvatures, and middle curvatures led to higher NCF compared with coronal. These findings are consistent with previous studies that examined the influence of curvature location on fracture resistance with continuous [26] and reciprocating [27] instrument systems. Instruments tested in those studies had low fatigue resistance when the curvature was located in the coronal and middle thirds compared with the apical third.…”

Section: Discussionsupporting

confidence: 92%

A novel model to evaluate the fatigue resistance of NiTi instruments: Rotational and axial movement at body temperature

Baird

Huang²,

Liu

et al. 2022

Aust Endodontic J

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To develop a model to test cyclic fatigue resistance of TruNatomy instruments undergoing rotational and axial movement at body temperature. A total of 288 Prime and Medium instruments were subjected to cyclic fatigue testing in simulated canals (at 37°C) using a model with either rotational movement only or rotational and axial movement simultaneously. Two different sized canals and three different types of curvatures were tested for each instrument (30/0.04 and 30/0.06 for Prime; 38/0.04 and 40/0.06 for Medium). The number of cycles to failure (fatigue resistance) was recorded. Rotational and axial movement of instruments led to greater fatigue resistance compared with rotational movement alone. Apical curvatures led to greater fatigue resistance than curvatures in the coronal and middle third. The developed dynamic model at body temperature to evaluate fatigue resistance of instrument closer simulates clinical scenarios.

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Section: Discussionsupporting

confidence: 92%

A novel model to evaluate the fatigue resistance of NiTi instruments: Rotational and axial movement at body temperature

Baird

Huang²,

Liu

et al. 2022

Aust Endodontic J

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“…There were no significant differences between WOG and Rec in canals with curvatures in the middle and coronal canals. Therefore, reciprocating instruments present lower resistance to cyclic fatigue when operated in canals with curvatures in the coronal and middle thirds when compared with curvatures in the apical thirds [26].…”

Section: Resultsmentioning

confidence: 99%

Research of the major clinical findings of the use of reciprocant files: a systematic review

Pessoa¹,

Reis²,

Souza³

et al. 2022

MedNEXT

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Introduction: In the context of root canal treatments, nickel-titanium endodontic rotary instruments fracture due to torsional overload or cyclic fatigue. Channels with bends located closer to the channel orifice and channels with double bends (S-shaped channels) have been shown to increase the risk of fatigue failure of rotating instruments. Thus, Yared was the first to report the use and effectiveness of reciprocating motions for rotary files, as he demonstrated that a single reciprocating file was sufficient to replace several files used in continuous rotation. Objective: A concise systematic review was carried out on the main results of clinical studies on the use of reciprocating files, to externalize the scientific evidence of these files to files used in continuous rotations. Methods: The present study followed the model of systematic literature review (PRISMA). The research was carried out from January 2022 to March 2022 and was developed based on Google Scholar, Scopus, PubMed, Scielo, and the Cochrane Library. The quality of scientific evidence of the studies was based on the GRADE instrument. The risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 85 articles were found. After the process of analyzing the quality of scientific evidence, 32 articles were selected. After analyzing the risk of bias, 8 recent clinical studies, from 2019 to 2022, were selected to compose this systematic review. Based on the clinical studies presented in the present study, it was evidenced that there is a significant statistical difference in the number of cycles in and out movement and wear time to failure between reciprocating and continuous rotary files. Furthermore, an endodontic treatment combining a single reciprocating file with a single cone showed similar clinical efficacy to treatment with hand file instrumentation and lateral compaction obturation. However, randomized clinical studies have shown that reciprocating instruments have less resistance to cyclic fatigue when operated in canals with curvatures in the coronal and middle thirds when compared with curvatures in the apical thirds.

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“…However, mechanical preparation in curved canals may lead to procedure errors such as ledge, zip, perforation. What is more, canals with curvatures located at the apical orifice has been shown higher risks of cyclic fatigue of rotary files [ 31 , 32 ], which may lead to instrument separation, result in unfavorable prognosis. In this research, it showed that the combination with canal curvature and needle working length can improve irrigation efficiency by increasing irrigation area and shear stress.…”

Section: Discussionmentioning

confidence: 99%

Influence of needle working length and root canal curvature on irrigation: a computational fluid dynamics analysis based on a real tooth

Zhou

Huang

et al. 2022

BMC Oral Health

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Backgrounds To compare the irrigation efficiency with different needle working length and different root canal curvature based on a real unshaped root canal using computational fluid dynamics (CFD) method. Methods Images of the root canal of the maxillary first molar after being prepared to .04/15 were scanned using micro-CT, and then imported into the software for three-dimensional reconstruction. A palatal root canal with a curvature of 23.4° was selected as the experiment canal. The needle working length of the 30-G flat needle was 4.75 mm, 5 mm, 5.25 mm and 5.5 mm short of apical foramen respectively, the flow pattern, irrigation velocity, shear stress were compared. The modified curved canals with a curvature of 0°, 5°, 10°, 20° and 30°were reconstructed via software. The flat needle was replaced at the optical inserted depth, and key parameters of irrigation efficiency were analyzed. Results Decreased needle working length had a positive impact on irrigation efficiency. With the optimal needle working length, the replacement of the apical irrigation fluid, the effective velocity, and wall shear stress were significantly improved in more severely curved root canals. With the same needle working depth and analogous canal curvature, irrigation efficiency is higher in real canal than that of modified canal. Conclusions Short needle working depth, large curvature and the anomalous inner wall of canals help to improve irrigation efficiency.

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Effect of canal curvature location on the cyclic fatigue resistance of reciprocating files

Cited by 11 publications

References 33 publications

A novel model to evaluate the fatigue resistance of NiTi instruments: Rotational and axial movement at body temperature

A novel model to evaluate the fatigue resistance of NiTi instruments: Rotational and axial movement at body temperature

Research of the major clinical findings of the use of reciprocant files: a systematic review

Influence of needle working length and root canal curvature on irrigation: a computational fluid dynamics analysis based on a real tooth

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