PSI - Issue 42

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Structural Integrity Procedia 00 (2019) 000 – 000 il l li t . i i t. tr t r l I t rit r i ( )

www.elsevier.com/locate/procedia . l i r. /l t / r i

ScienceDirect

Procedia Structural Integrity 42 (2022) 631–638

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 One of the purposes of this study is to compare the fatigue resistance of different generations of endodontic files made of nickel titanium (NiTi). Additionally, it is intended to investigate the possibility of using Non-Destructive Testing (NDT), mainly eddy currents testing (ECT) and thermography, to detect fatigue microcracks responsible for most of the fractures of the endodontic files in a clinical environment. The instruments were placed in rotation in an experimental setup designed to simulate a root canal with a radius of curvature of 5 mm applied over an angle of 45°. HyFlex ™ EDM rotary files (Coltene, Switzerland) were tested and compared with the results obtained for HyFlex ™ CM conventional machined files. Experimental results showed that the recent generation of instruments manufactured by the Electrical Discharge Machining (EDM) process is much more resistant to fatigue when compared to the conventional controlled memory (CM) files. For the NDT application, an artificial defect was introduced in the apical region of a HyFlex CM file. Subsequently, ten customized ECT probes were designed, produced, and validated experimentally. In addition, numerical simulations were carried out, replicating the parameters and conditions of the two probes that showed better detectability. The methodologies developed for the inspection of files through ECT proved unable to detect the faulty region unambiguously, mainly due to NiTi alloys' taper and the electromagnetic properties. On the other hand, thermography allowed to detect the defect introduced in the endodontic file, although with some difficulty due to its small size. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 Keywords: Structural integrity; Endodontic files; Eddy Currents Testing (ECT); Thermography; Fatigue resistance. tit i i i . iti ll , it i i t t i ti t t i ilit i t ti ti , i l t t ti t , t t t ti i i l t t t t ti il i li i l i t. i t t l i t ti i i t l t i t i l t t l it i t li l . l t il lt , it l t t it t lt t i l ti l i il . i t l lt t t t t ti i t t t t l t i l i i i i i t t t ti t t ti l t ll il . t li ti , ti i i l t i t i t i l i l il . tl , t t i i , , li t i t ll . iti , i l i l ti i t, li ti t t iti t t t t tt t t ilit . t l i l t i ti il t l t t t t lt i i l , i l t i i ll ' t t l t ti ti . t t , t ll t t t t t i t i t ti il , lt it i i lt t it ll i . t . lish l i . . This is an open access article under the CC BY-NC-ND lice tt :// ti . /li / / . / i i ilit t : tr t r l i t rit ; ti fil ; rr t ti ( ); r r ; ti r i t . 23 European Conference on Fracture - ECF23 Structural integrity of endodontic files using rotating bending tests, transient thermography and eddy currents testing Guilherme Saldanha a , Miguel A. Machado a,b , Telmo G. Santos a,b , Rui F. Martins a,b * a UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal b Laboratório Associado de Sistemas Inteligentes, LASI, 4800-058 Guimarães, Portugal , , , a I I, t t f i l I t i l i i , l f i l , i i i , - i , t l b t i i i t I t li t , I, - i , t l Abstract t t i t i t t ti i t i t ti ti il i l

* Corresponding author. Tel.: +351 21 294 85 67; fax: +351 21 294 85 31. E-mail address: rfspm@fct.unl.pt i t r. l.: ; f : . - il : rf f t. l. t rr

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 l i r . . i i rti l r t - - li ( tt :// r ti . r /li / - - / . /) i i ilit t - t r . li

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.080