{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T12:07:26Z","timestamp":1790078846153,"version":"4.0.1"},"reference-count":40,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T00:00:00Z","timestamp":1789948800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Dent. J.","Dentistry Journal"],"abstract":"<jats:p>Background\/Objectives: This study aimed to present the design of a novel abutment screw head featuring an integrated retrieval mechanism and to evaluate the retrievability of four prototype designs. Methods: In this in vitro mechanical study, the modified screws were produced by replicating the macrogeometry of the Br\u00e5nemark and Klockner VEGA abutment screws and incorporating a secondary screw chamber below the original one, with a 1.0 mm or 0.9 mm hexagonal design. Sixty screws were manufactured, fifteen for each group: BC0.9, BC1.0, KC0.9, and KC1.0. Retrieval success and the relationship between peak tightening and loosening torque were evaluated (\u03b1 = 0.05). Results: All screws tolerated tightening at a torque 20% above the manufacturer\u2019s recommendation. Most specimens from BC0.9 and KC0.9 failed during loosening, while all specimens in BC1.0 and KC1.0 were successfully retrieved. Regarding peak tightening torque and the loosening-to-tightening ratio, neither prototype exhibited a statistically significant correlation. BC1.0 demonstrated a statistically significant positive correlation between peak tightening torque and peak loosening torque, whereas KC1.0 showed a weaker relationship; detailed correlation coefficients and p-values are reported in the Results. Conclusions: Under the in vitro conditions tested, the prosthetic screw incorporating a 1.0 mm secondary retrieval head demonstrated reliable retrieval performance, supporting its potential as a simple retrieval system. These findings represent a proof-of-concept and require further mechanical and clinical investigation before clinical application.<\/jats:p>","DOI":"10.3390\/dj14090613","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T10:21:48Z","timestamp":1790072508000},"page":"613","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Novel Abutment Screw Head Design with an Integrated Retrieval Feature: An In Vitro Study"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1209-8127","authenticated-orcid":false,"given":"Ricardo","family":"Batista","sequence":"first","affiliation":[{"name":"Department of Prosthodontics, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7226-0715","authenticated-orcid":false,"given":"Andr\u00e9","family":"Moreira","sequence":"additional","affiliation":[{"name":"Department of Prosthodontics, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal"},{"name":"Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), 4200-465 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5016-0868","authenticated-orcid":false,"given":"Nuno","family":"Alves","sequence":"additional","affiliation":[{"name":"Centre for Rapid and Sustainable Product Development, ESTG (School of Technology and Management), Polytechnic Institute of Leiria, 2411-901 Leiria, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8583-8096","authenticated-orcid":false,"given":"Maria Helena","family":"Figueiral","sequence":"additional","affiliation":[{"name":"Department of Prosthodontics, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal"},{"name":"Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), 4200-465 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jo\u00e3o","family":"Sampaio-Fernandes","sequence":"additional","affiliation":[{"name":"Department of Prosthodontics, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal"},{"name":"Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), 4200-465 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"732","DOI":"10.1016\/j.prosdent.2021.06.053","article-title":"Mechanical complications of implant-supported restorations with internal conical connection implants: A 14-year retrospective study","volume":"129","author":"Yi","year":"2023","journal-title":"J. Prosthet. Dent."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5490","DOI":"10.4103\/jfmpc.jfmpc_1343_20","article-title":"Abutment screw loosening in implants: A literature review","volume":"9","author":"Alsubaiy","year":"2020","journal-title":"J. Fam. Med. Prim. Care"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Vinhas, A.S., Aroso, C., Salazar, F., L\u00f3pez-Jarana, P., R\u00edos-Santos, J.V., and Herrero-Climent, M. (2020). Review of the Mechanical Behavior of Different Implant-Abutment Connections. Int. J. Environ. Res. Public Health, 17.","DOI":"10.3390\/ijerph17228685"},{"key":"ref_4","first-page":"529","article-title":"Elongation and preload stress in dental implant abutment screws","volume":"10","author":"Haack","year":"1995","journal-title":"Int. J. Oral Maxillofac. Implants"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"102226","DOI":"10.1016\/j.jebdp.2025.102226","article-title":"The efficacy of techniques for managing fractured dental implant abutment screws: A systematic review and meta-analysis","volume":"26","author":"Arshad","year":"2026","journal-title":"J. Evid. Based Dent. Pract."},{"key":"ref_6","first-page":"100010","article-title":"Effects of abutment screw preload and preload simulation techniques on dental implant lifetime","volume":"1","author":"Satpathy","year":"2022","journal-title":"JADA Found. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"264","DOI":"10.4103\/0976-237X.132382","article-title":"Noninvasive method for retrieval of broken dental implant abutment screw","volume":"5","author":"Gooty","year":"2014","journal-title":"Contemp. Clin. Dent."},{"key":"ref_8","first-page":"76","article-title":"Implants and components: Entering the new millennium","volume":"15","author":"Binon","year":"2000","journal-title":"Int. J. Oral Maxillofac. Implants"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"473","DOI":"10.1016\/j.joms.2003.07.008","article-title":"Screw head design: An experimental study to assess the influence of design on performance","volume":"62","author":"Spencer","year":"2004","journal-title":"J. Oral Maxillofac. Surg."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1034\/j.1600-0501.2000.110209.x","article-title":"Fractured prosthetic abutments in osseointegrated implants: A technical complication to cope with","volume":"11","author":"Luterbacher","year":"2000","journal-title":"Clin. Oral Implants Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1016\/j.prosdent.2017.05.016","article-title":"A risk-based decision making tree for managing fractured abutment and prosthetic screws: A systematic review","volume":"119","author":"Mizumoto","year":"2018","journal-title":"J. Prosthet. Dent."},{"key":"ref_12","first-page":"120","article-title":"A simple and cost effective method used for removal of a fractured implant abutment screw: A case report","volume":"5","author":"Satwalekar","year":"2013","journal-title":"J. Int. Oral Health"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1147","DOI":"10.1111\/jerd.12959","article-title":"Deformation of implant retaining screws: Study with stereoscopic microscopy and micro-CT","volume":"34","author":"Batista","year":"2022","journal-title":"J. Esthet. Restor. Dent."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"106219","DOI":"10.1016\/j.jdent.2025.106219","article-title":"Impact of repeated tightening and loosening on the implant-prosthetic screw joint: A systematic review and meta-analysis","volume":"164","author":"Shui","year":"2026","journal-title":"J. Dent."},{"key":"ref_15","first-page":"60","article-title":"Evaluation of implant abutment screw head deformation in hexagonal and star designs after successive tightening and loosening","volume":"15","author":"Ghaffari","year":"2023","journal-title":"J. Adv. Periodontol. Implant Dent."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Nourizadeh, A., Ghasemi, S., Shafiee, E., JafarZadeh, S., and Bakhtiari, F. (2025). A comparative study of deformation in hexagonal and star-shaped implant screwdriver heads. BMC Oral Health, 25.","DOI":"10.1186\/s12903-025-06090-3"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"882","DOI":"10.1016\/j.prosdent.2020.11.026","article-title":"Effects of tightening torque on screw stress and formation of implant-abutment microgaps: A finite element analysis","volume":"127","author":"He","year":"2022","journal-title":"J. Prosthet. Dent."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4198","DOI":"10.6026\/973206300214198","article-title":"In vitro study on the mechanical strength of abutment screw head under compressive forces","volume":"21","author":"Chaudhary","year":"2025","journal-title":"Bioinformation"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Vinhas, A.S., Aroso, C., Salazar, F., Relvas, M., Braga, A.C., R\u00edos-Carrasco, B., Gil, J., Rios-Santos, J.V., Fern\u00e1ndez-Palac\u00edn, A., and Herrero-Climent, M. (2022). In vitro study of preload loss in different implant-abutment connection designs. Materials, 15.","DOI":"10.3390\/ma15041392"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/S0022-3913(03)00212-9","article-title":"Clinical complications with implants and implant prostheses","volume":"90","author":"Goodacre","year":"2003","journal-title":"J. Prosthet. Dent."},{"key":"ref_21","first-page":"e1355","article-title":"Preload loss of abutment screws after dynamic fatigue in single implant-supported restorations: A systematic review","volume":"9","author":"Montero","year":"2017","journal-title":"J. Clin. Exp. Dent."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"287","DOI":"10.4103\/jispcd.JISPCD_318_21","article-title":"Retrieval of Fractured Implant Abutment Screws: A Narrative Review","volume":"12","author":"Nayana","year":"2022","journal-title":"J. Int. Soc. Prev. Community Dent."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"549","DOI":"10.1067\/mpr.2001.118922","article-title":"Retrieval technique for fractured implant screws","volume":"86","author":"Williamson","year":"2001","journal-title":"J. Prosthet. Dent."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/S0011-8532(22)00606-1","article-title":"Implant screw mechanics","volume":"42","author":"McGlumphy","year":"1998","journal-title":"Dent. Clin. N. Am."},{"key":"ref_25","first-page":"4842072","article-title":"Hollow abutment screw design for easy retrieval in case of screw fracture in dental implant system","volume":"1","author":"Sim","year":"2017","journal-title":"J. Healthc. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1016\/j.prosdent.2015.08.027","article-title":"Managing a fractured implant: A clinical report","volume":"115","author":"Oh","year":"2016","journal-title":"J. Prosthet. Dent."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.prosdent.2019.12.015","article-title":"Alternative approach to salvaging an implant with a fractured screw fragment: A clinical report","volume":"125","author":"Yi","year":"2021","journal-title":"J. Prosthet. Dent."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/S0022-3913(11)60015-2","article-title":"A technique to retrieve fractured implant screws","volume":"105","author":"Yilmaz","year":"2011","journal-title":"J. Prosthet. Dent."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"475","DOI":"10.1563\/AAID-JOI-D-11-00126","article-title":"Ultrasonic oscillations for conservative retrieval of a rare fracture of implant healing abutment","volume":"39","author":"Bhandari","year":"2013","journal-title":"J. Oral Implantol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"812","DOI":"10.1016\/j.prosdent.2018.01.026","article-title":"An accessory technique for the intraoral removal of a fractured implant abutment screw","volume":"120","author":"Chen","year":"2018","journal-title":"J. Prosthet. Dent."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/j.prosdent.2013.04.007","article-title":"A technique for retrieving fractured implant screws","volume":"111","author":"Imam","year":"2014","journal-title":"J. Prosthet. Dent."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1016\/S0022-3913(10)00133-2","article-title":"Retrieval of a stripped abutment screw: A clinical report","volume":"104","author":"Jacobs","year":"2010","journal-title":"J. Prosthet. Dent."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1111\/j.1532-849X.2004.04006.x","article-title":"Retrofitting a cast dowel-core on salvaged dental implants","volume":"13","author":"Pipko","year":"2004","journal-title":"J. Prosthodont."},{"key":"ref_34","first-page":"102","article-title":"A systematic review of biologic and technical complications with fixed implant rehabilitations for edentulous patients","volume":"27","author":"Papaspyridakos","year":"2012","journal-title":"Int. J. Oral Maxillofac. Implants"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1097\/01.id.0000217907.18396.18","article-title":"Consensus conference panel report: Crown height space guidelines for implant dentistry\u2014Part 2","volume":"15","author":"Misch","year":"2006","journal-title":"Implant Dent."},{"key":"ref_36","first-page":"98","article-title":"Effect of abutment height on retention of single cement-retained wide- and narrow-platform implant-supported restorations","volume":"6","author":"Abolfazli","year":"2012","journal-title":"J. Dent. Res. Dent. Clin. Dent. Prospects"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"242","DOI":"10.1563\/1548-1336(2003)029<0242:ISMATS>2.3.CO;2","article-title":"Implant screw mechanics and the settling effect: Overview","volume":"29","author":"Winkler","year":"2003","journal-title":"J. Oral Implantol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1067\/mpr.2001.116230","article-title":"Implant abutment screw rotations and preloads for four different screw materials and surfaces","volume":"86","author":"Martin","year":"2001","journal-title":"J. Prosthet. Dent."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1016\/j.prosdent.2014.09.021","article-title":"Effect of the coefficient of friction and tightening speed on the preload induced at the dental implant complex with the finite element method","volume":"113","author":"Bulaqi","year":"2015","journal-title":"J. Prosthet. Dent."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1111\/clr.12623","article-title":"Effect of double conical abutment screw on implant preload","volume":"27","author":"Arnetzl","year":"2016","journal-title":"Clin. Oral Implants Res."}],"container-title":["Dentistry Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2304-6767\/14\/9\/613\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T11:23:06Z","timestamp":1790076186000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2304-6767\/14\/9\/613"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,21]]},"references-count":40,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["dj14090613"],"URL":"https:\/\/doi.org\/10.3390\/dj14090613","relation":{},"ISSN":["2304-6767"],"issn-type":[{"value":"2304-6767","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,21]]}}}