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This study assessed how alloy type and fragment length affect the efficiency of fractured file removal under standardized simulated conditions. Simulated J-shaped canal blocks were prepared and ProTaper Gold F2 and ProTaper Universal F2 fragments were sectioned to 3 mm or 4 mm lengths, with retrieval performed using Gates-Glidden drills and ultrasonic instruments. Retrieval time was recorded and analyzed at a 95% significance level, showing meaningful effects of both fragment length and alloy type.","Yoon etal. BMCOral Health (2026) 26:38 BMC Oral Health  \n[https://doi.org/10.1186/s12903-025-07429-6](https://doi.org/10.1186/s12903-025-07429-6)  \nRESEARCH Open Access  \nEfficiency of fractured file retrieval according to different nickel-titanium alloys and fragment lengths  \nJoon Hyuk Yoon 1, Yoshitsugu Terauchi2, Jae-Hoon Kim3, Sang Won Kwak 1 and Hyeon-Cheol Kim 1,4*  \nAbstract  \nBackground The fracture of nickel-titanium (NiTi) rotary files may be considered a direct cause of endodontic treatment failure. This study aimed to evaluate the effect of alloy type and fragment length on the efficiency of fractured file removal under standardized simulated conditions.  \nMethods Simulated J-shape canal blocks were shaped up to ProTaper Gold F2 size. The file tips of ProTaper Gold (PTG) F2 and ProTaper Universal (PTU) F2 files were artificially sectioned to make the fragments of 3-mm and 4-mm, respectively (n = 25 for each system and fragment length) . The file fragments were positioned 1.5 mm coronal ly from the apical end of the simulated canal. The file fragments were retrieved using Gates-Glidden drill s and ultrasonic instruments at a single optimized power setting. Retrieval time, defined as the duration from ultrasonic activation until fragment removal, was recorded. Statistical analysis evaluated the effects of alloy type and fragment length with a significance level of 95% .  \nResults For 3-mm fragments, the PTU files demonstrated significantly faster retrieval times than the PTG files  \n(p \u003C 0. 05) . However, no significant difference in retrieval time was found between PTG and PTU files for 4-mm fragments. Regardless of the file alloy types, the 3-mm fragments were removed in a significantly shorter time than the 4-mm fragments (p \u003C 0. 05) .  \nConclusion Under controlled resin model conditions, both fragment length and alloy type significantly influence fractured NiTi file retrieval efficiency.  \nKeywords File fracture, Fragment length, Heat treatment, Nickel-titanium file, Retrieval, Ultrasonic  \n*Correspondence:  \nHyeon-Cheol Kim  \n[golddent@pusan.ac.kr](golddent@pusan.ac.kr)  \n1Department of Conservative Dentistry, Dental and Life Science Institute, School of Dentistry, Pusan National University and Dental Research Institute, Yangsan, Korea  \n2Private Endodontic Practice and Dental Arts Academy, Yokohama, Japan 3Department of Dental Education, Dental and Life Science Institute, School of Dentistry, Pusan National University and Dental Research Institute, Yangsan, Korea  \n4Department of Conservative Dentistry, Pusan National University School of Dentistry, Geumo-ro 20, Yangsan, Gyeongsangnam-do  \n50612, South Korea  \n© The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit [http://creati](http://creati)[vecommons.org/l](vecommons.org/l)icenses/by-nc-nd/4.0/.  \nYoon et al. BMC Oral Health (2026) 26:38  \nBackground  \nNickel-titanium (NiTi) rotary instruments have gained worldwide acceptance since their introduction for root canal treatments. The favorable perception of these instruments, particularly","cbCaijw0TiVDAOU9","https://ap.wps.com/l/cbCaijw0TiVDAOU9","pdf",1145163,"English","en",105,"# Background\n# Methods\n# Results\n# Conclusion","[{\"question\":\"What factors were tested for fractured NiTi file removal efficiency?\",\"answer\":\"The study tested alloy type and fragment length, using standardized simulated canal conditions.\"},{\"question\":\"How were file fragments prepared and where were they positioned?\",\"answer\":\"ProTaper Gold F2 and ProTaper Universal F2 files were sectioned to create fragments of 3 mm and 4 mm, then positioned 1.5 mm coronally from the apical end of the simulated canal.\"},{\"question\":\"What were the main findings about fragment length and alloy type?\",\"answer\":\"For 3-mm fragments, PTU showed significantly faster retrieval than PTG. For 4-mm fragments, retrieval times were not significantly different between PTG and PTU, and 3-mm fragments were removed faster than 4-mm fragments regardless of alloy type.\"}]","Efficiency of fractured file retrieval according to different nickel-titanium alloys and fragment lengths | PDF",1790750130,18,{"code":4,"msg":81,"data":82},"ok",{"site_id":74,"language":73,"slug":83,"title":65,"keywords":84,"description":66,"schema_data":85,"social_meta":139,"head_meta":141,"extra_data":143,"updated_unix":144},"efficiency-of-fractured-file-retrieval-according-to-different-nickel-titanium-alloys-and-fragment-lengths","",{"@graph":86,"@context":138},[87,101,121],{"@type":88,"itemListElement":89},"BreadcrumbList",[90,94,96,99],{"item":91,"name":92,"@type":93,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":95,"name":9,"@type":93,"position":14},"https://docshare.wps.com/document/",{"item":97,"name":40,"@type":93,"position":98},"https://docshare.wps.com/document/research-report/",3,{"item":100,"name":65,"@type":93,"position":19},"https://docshare.wps.com/document/efficiency-of-fractured-file-retrieval-according-to-different-nickel-titanium-alloys-and-fragment-lengths/457680/",{"url":100,"name":65,"@type":102,"image":103,"author":108,"headline":65,"publisher":110,"fileFormat":113,"inLanguage":73,"description":66,"dateModified":114,"datePublished":115,"encodingFormat":113,"isAccessibleForFree":116,"interactionStatistic":117},"DigitalDocument",{"url":104,"@type":105,"width":106,"height":107},"https://docshare.wps.com/thumbnails/efficiency-of-fractured-file-retrieval-according-to-different-nickel-titanium-alloys-and-fragment-lengths/457680.png","ImageObject",300,407,{"name":63,"@type":109},"Person",{"url":91,"name":111,"@type":112},"DocShare","Organization","application/pdf","2026-10-08","2026-09-30",true,{"@type":118,"interactionType":119,"userInteractionCount":24},"InteractionCounter",{"@type":120},"ViewAction",{"@type":122,"mainEntity":123},"FAQPage",[124,130,134],{"name":125,"@type":126,"acceptedAnswer":127},"What factors were tested for fractured NiTi file removal efficiency?","Question",{"text":128,"@type":129},"The study tested alloy type and fragment length, using standardized simulated canal conditions.","Answer",{"name":131,"@type":126,"acceptedAnswer":132},"How were file fragments prepared and where were they positioned?",{"text":133,"@type":129},"ProTaper Gold F2 and ProTaper Universal F2 files were sectioned to create fragments of 3 mm and 4 mm, then positioned 1.5 mm coronally from the apical end of the simulated canal.",{"name":135,"@type":126,"acceptedAnswer":136},"What were the main findings about fragment length and alloy type?",{"text":137,"@type":129},"For 3-mm fragments, PTU showed significantly faster retrieval than PTG. For 4-mm fragments, retrieval times were not significantly different between PTG and PTU, and 3-mm fragments were removed faster than 4-mm fragments regardless of alloy type.","https://schema.org",{"og:url":100,"og:type":140,"og:title":65,"og:site_name":111,"og:description":66},"article",{"robots":142,"canonical":100},"index,follow",{"doc_id":61,"site_id":74},1791367160]