{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T05:51:44Z","timestamp":1778219504704,"version":"3.51.4"},"reference-count":29,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2024,5,15]],"date-time":"2024-05-15T00:00:00Z","timestamp":1715731200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>The resistance of nickel\u2013titanium endodontic instruments against cyclic fatigue failure remains a significant concern in clinical settings. This study aimed to assess the cyclic fatigue strength of five nickel\u2013titanium rotary systems, while correlating the results with the instruments\u2019 geometric and metallurgical characteristics. A total of 250 new instruments (sizes S1\/A1, S2\/A2, F1\/B1, F2\/B2, F3\/B3) from ProTaper Gold, ProTaper Universal, Premium Taper Gold, Go-Taper Flex, and U-Files systems underwent mechanical testing. Prior to experimental procedures, all instruments were meticulously inspected to identify irregularities that could affect the investigation. Using a stereomicroscope, design characteristics such as the number of spirals, length, spirals per millimeter, and average helical angle of the active blade were determined. The surface finishing characteristics of the instruments were examined using a scanning electron microscope. Differential scanning calorimetry was employed to establish the instruments\u2019 phase transformation temperatures, while energy-dispersive X-ray spectroscopy was utilized to analyze the elemental composition of the alloy. The instruments were subjected to cyclic fatigue testing within a stainless steel non-tapered artificial canal featuring a 6 mm radius and 86 degrees of curvature. Appropriate statistical tests were applied to compare groups, considering a significance level of 0.05. The assessed design characteristics varied depending on the instrument type. The least irregular surface finishing was observed in U-Files and Premium Taper Gold files, while the most irregular surface was noted in Go-Taper Flex. All instruments exhibited near-equiatomic proportions of nickel and titanium elements, whereas ProTaper Universal and U-Files instruments demonstrated lower phase transformation temperatures compared to their counterparts. Larger-sized instruments, as well as ProTaper Universal and U-Files, tended to display lower cyclic fatigue strength results. Overall, the design, metallurgical, and cyclic fatigue outcomes varied among instruments and systems. Understanding these outcomes may assist clinicians in making more informed decisions regarding instrument selection.<\/jats:p>","DOI":"10.3390\/ma17102345","type":"journal-article","created":{"date-parts":[[2024,5,15]],"date-time":"2024-05-15T06:14:42Z","timestamp":1715753682000},"page":"2345","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Comprehensive Assessment of Cyclic Fatigue Strength in Five Multiple-File Nickel\u2013Titanium Endodontic Systems"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6932-2038","authenticated-orcid":false,"given":"Jorge N. R.","family":"Martins","sequence":"first","affiliation":[{"name":"Faculdade de Medicina Dent\u00e1ria, Universidade de Lisboa, 1600-277 Lisboa, Portugal"},{"name":"LIBPhys-FCT UID\/FIS\/04559\/2013, 1600-277 Lisboa, Portugal"},{"name":"Grupo de Investiga\u00e7\u00e3o em Bioquimica e Biologia Oral (GIBBO), Unidade de Investiga\u00e7\u00e3o em Ci\u00eancias Orais e Biom\u00e9dicas (UICOB), 1600-277 Lisboa, Portugal"},{"name":"Centro de Estudos de Medicina Dent\u00e1ria Baseada na Evid\u00eancia (CEMDBE), 1600-277 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6445-8243","authenticated-orcid":false,"given":"Emmanuel J. N. L.","family":"Silva","sequence":"additional","affiliation":[{"name":"Department of Endodontics, School of Dentistry, Grande Rio University (UNIGRANRIO), Rio de Janeiro 21210-623, Brazil"},{"name":"Department of Endodontics, Fluminense Federal University, Rio de Janeiro 24220-900, Brazil"},{"name":"Department of Endodontics, Rio de Janeiro University (UERJ), Rio de Janeiro 20550-013, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1966-8281","authenticated-orcid":false,"given":"Duarte","family":"Marques","sequence":"additional","affiliation":[{"name":"Faculdade de Medicina Dent\u00e1ria, Universidade de Lisboa, 1600-277 Lisboa, Portugal"},{"name":"LIBPhys-FCT UID\/FIS\/04559\/2013, 1600-277 Lisboa, Portugal"},{"name":"Grupo de Investiga\u00e7\u00e3o em Bioquimica e Biologia Oral (GIBBO), Unidade de Investiga\u00e7\u00e3o em Ci\u00eancias Orais e Biom\u00e9dicas (UICOB), 1600-277 Lisboa, Portugal"},{"name":"Centro de Estudos de Medicina Dent\u00e1ria Baseada na Evid\u00eancia (CEMDBE), 1600-277 Lisboa, Portugal"}]},{"given":"Francisco M.","family":"Braz Fernandes","sequence":"additional","affiliation":[{"name":"CENIMAT\/I3N, Department of Materials Science, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5277-9827","authenticated-orcid":false,"given":"Marco A.","family":"Versiani","sequence":"additional","affiliation":[{"name":"Dental Specialty Center, Brazilian Military Police, Belo Horizonte 30350-190, Brazil"}]}],"member":"1968","published-online":{"date-parts":[[2024,5,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1111\/j.1601-1546.2005.00152.x","article-title":"Mechanical preparation of root canals: Shaping goals, techniques and means","volume":"10","author":"Peters","year":"2005","journal-title":"Endod. 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Dentistry\u2014Root Canal Instruments\u2014Part 1: General Requirements and Test Methods (Standard No. ISO 3630-3631:2008)."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/17\/10\/2345\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:42:44Z","timestamp":1760107364000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/17\/10\/2345"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,5,15]]},"references-count":29,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2024,5]]}},"alternative-id":["ma17102345"],"URL":"https:\/\/doi.org\/10.3390\/ma17102345","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,5,15]]}}}