{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,18]],"date-time":"2026-04-18T15:54:44Z","timestamp":1776527684384,"version":"3.51.2"},"reference-count":37,"publisher":"Public Library of Science (PLoS)","issue":"4","license":[{"start":{"date-parts":[[2021,4,1]],"date-time":"2021-04-01T00:00:00Z","timestamp":1617235200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100009624","name":"Yonsei University College of Dentistry","doi-asserted-by":"publisher","award":["2-2018-0027"],"award-info":[{"award-number":["2-2018-0027"]}],"id":[{"id":"10.13039\/501100009624","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>This study aimed to analyze fracture strength <jats:italic>in vitro<\/jats:italic> by varying the axial height of the titanium insert and the labial height of the zirconia abutment in an internal connection implant to identify the titanium insert axial height with optimal mechanical stability. Sixty implants with an internal connection system were used. Two-piece zirconia abutments were used with the titanium inserts. Combinations of different titanium insert axial heights (mm) and zirconia abutment labial heights (mm) constituted five groups: Gr1 (1\u20133), Gr2 (3\u20133), Gr3 (3\u20135), Gr4 (5\u20133), and Gr5 (5\u20135). After thermocycling, a fracture load test was performed with a universal testing machine. The initial deformation load and the fracture load were measured and analyzed. The fractured surface and cross-section of the specimens were examined by scanning electron microscopy (SEM). The groups of titanium inserts with axial heights of 3 mm and 5 mm showed significantly greater initial deformation load and fracture load than the group with an axial height of 1 mm (<jats:italic>p<\/jats:italic> &lt; 0.05), but there was no significant difference between the two groups with axial heights of 3 mm and 5 mm. The labial height of the zirconia abutment had no significant influence on the initial deformation load and fracture load. In some specimens in Gr4 and Gr5, cracking or bending of the titanium insert and abutment screw was observed on SEM. The axial height of the titanium insert should be designed to not be less than 3 mm to increase the fracture strength and promote the long-term stability of implants.<\/jats:p>","DOI":"10.1371\/journal.pone.0249208","type":"journal-article","created":{"date-parts":[[2021,4,1]],"date-time":"2021-04-01T18:26:17Z","timestamp":1617301577000},"page":"e0249208","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":4,"title":["Fracture strength analysis of titanium insert-reinforced zirconia abutments according to the axial height of the titanium insert with an internal connection"],"prefix":"10.1371","volume":"16","author":[{"given":"Seung-rye","family":"Song","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kyeong-Mee","family":"Park","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8186-2109","authenticated-orcid":true,"given":"Bock-Young","family":"Jung","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2021,4,1]]},"reference":[{"issue":"5","key":"pone.0249208.ref001","first-page":"850","article-title":"In vitro study of the influence of the type of connection on the fracture load of zirconia abutments with internal and external implant-abutment connections","volume":"24","author":"I Sailer","year":"2009","journal-title":"Int J Oral Maxillofac Implants"},{"issue":"1","key":"pone.0249208.ref002","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0142-9612(98)00010-6","article-title":"Zirconia as a ceramic biomaterial","volume":"20","author":"C Piconi","year":"1999","journal-title":"Biomaterials"},{"issue":"2","key":"pone.0249208.ref003","doi-asserted-by":"crossref","first-page":"346","DOI":"10.11607\/jomi.3768","article-title":"Fracture strength study of internally connected zirconia abutments reinforced with titanium inserts","volume":"30","author":"HJ Chun","year":"2015","journal-title":"Int J Oral Maxillofac Implants"},{"issue":"2","key":"pone.0249208.ref004","doi-asserted-by":"crossref","first-page":"488","DOI":"10.11607\/jomi.2772","article-title":"In vitro fatigue and fracture strength testing of one-piece zirconia implant abutments and zirconia implant abutments connected to titanium cores","volume":"28","author":"M Stimmelmayr","year":"2013","journal-title":"Int J Oral Maxillofac Implants"},{"issue":"5","key":"pone.0249208.ref005","doi-asserted-by":"crossref","first-page":"380","DOI":"10.1111\/j.1365-2842.2005.01571.x","article-title":"Fracture resistance of single-tooth implant-supported all-ceramic restorations after exposure to the artificial mouth","volume":"33","author":"W Att","year":"2006","journal-title":"J Oral Rehabil"},{"issue":"4","key":"pone.0249208.ref006","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1111\/clr.13139","article-title":"Fracture strength of zirconia implant abutments on narrow diameter implants with internal and external implant abutment connections: A study on the titanium resin base concept","volume":"29","author":"I Sailer","year":"2018","journal-title":"Clin Oral Implants Res"},{"issue":"6","key":"pone.0249208.ref007","first-page":"616","article-title":"Zirconia implant abutment fracture: clinical case reports and precautions for use","volume":"22","author":"MN Aboushelib","year":"2009","journal-title":"Int J Prosthodont"},{"issue":"6","key":"pone.0249208.ref008","first-page":"1029","article-title":"A comparison of fabrication precision and mechanical reliability of 2 zirconia implant abutments","volume":"23","author":"RB Kerstein","year":"2008","journal-title":"Int J Oral Maxillofac Implants"},{"issue":"6","key":"pone.0249208.ref009","doi-asserted-by":"crossref","first-page":"749","DOI":"10.1016\/j.prosdent.2016.09.008","article-title":"Load to failure of different zirconia implant abutments with titanium components","volume":"117","author":"F Mascarenhas","year":"2017","journal-title":"J Prosthet Dent"},{"key":"pone.0249208.ref010","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1111\/j.1600-0757.2007.00243.x","article-title":"Ceramic abutments and ceramic oral implants. 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