{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T12:13:49Z","timestamp":1788783229553,"version":"build-2803163510"},"reference-count":36,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T00:00:00Z","timestamp":1782172800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T00:00:00Z","timestamp":1788739200000},"content-version":"vor","delay-in-days":76,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Oral Health"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Full-coverage restorations are often required for primary molars with extensive carious destruction. Stainless steel crowns remain the long-standing reference, while prefabricated zirconia and polymer-based crowns have become tooth-colored alternatives. Direct comparisons under a single thermomechanical protocol, with separate wear and fracture cohorts, remain limited. This in vitro study quantified post-aging occlusal wear and compressive fracture load in four prefabricated crown systems for mandibular second primary molars.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Eighty crowns were tested, with 10 specimens per material for each outcome: two prefabricated zirconia crowns, one polymer-based crown, and one stainless steel crown. Identical resin dies were 3D-printed and all crowns were luted with glass-ionomer cement. All specimens underwent 10,000 thermal cycles between 5\u00a0\u00b0C and 55\u00a0\u00b0C. The wear cohort underwent 150,000 chewing cycles at 50 N and 1.2\u00a0Hz, and wear was scored on a 0\u20133 scale by two blinded examiners. The fracture cohort was loaded to failure. Wear scores were compared using Kruskal\u2013Wallis and Dunn\u2013Bonferroni tests; fracture loads were analyzed using one-way ANOVA and Tukey HSD.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Mean wear scores were 1.1\u2009\u00b1\u20090.3 for NuSmile, 1.2\u2009\u00b1\u20090.4 for ProfZr, 1.7\u2009\u00b1\u20090.4 for SSC, and 2.2\u2009\u00b1\u20090.4 for BioFlx. The zirconia groups did not differ significantly (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.68), whereas both showed lower wear scores than SSC (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.04) and BioFlx (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.01). SSC also showed lower wear scores than BioFlx (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.03). Mean fracture loads were 3148.4\u2009\u00b1\u2009643.4 N for BioFlx, 2703.4\u2009\u00b1\u2009243.1 N for SSC, 1076.1\u2009\u00b1\u2009186.9 N for NuSmile, and 565.5\u2009\u00b1\u2009159.6 N for ProfZr (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). BioFlx and SSC did not differ significantly (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.093), while both exceeded the zirconia groups (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.001). NuSmile exceeded ProfZr (\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.043).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Under this in vitro model, zirconia crowns showed the lowest wear scores, whereas BioFlx and SSC showed the highest fracture loads. Each material demonstrated a distinct mechanical profile. Laboratory rankings alone should not guide clinical recommendations; long-term clinical studies are needed.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s12903-026-08912-4","type":"journal-article","created":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T13:47:07Z","timestamp":1782222427000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Wear resistance and fracture strength of BioFlx, zirconia and stainless steel crowns for primary molars after thermomechanical aging: an in vitro comparative study"],"prefix":"10.1186","volume":"26","author":[{"given":"Alp Abidin","family":"Ate\u015f\u00e7i","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dilek \u00d6zge","family":"Y\u0131lmaz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Berk","family":"Gergit","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M\u00fcnevver \u00c7oruh","family":"K\u0131l\u0131\u00e7","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"H\u00fcseyin","family":"\u015eim\u015fek","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,6,23]]},"reference":[{"issue":"1","key":"8912_CR1","doi-asserted-by":"publisher","first-page":"17","DOI":"10.1016\/j.cden.2018.08.003","volume":"63","author":"DL Chi","year":"2019","unstructured":"Chi DL, Scott JM. Added sugar and dental caries in children: a scientific update and future steps. Dent Clin North Am. 2019;63(1):17\u201333.","journal-title":"Dent Clin North Am"},{"issue":"11","key":"8912_CR2","doi-asserted-by":"publisher","first-page":"1396","DOI":"10.1016\/j.jdent.2014.06.009","volume":"42","author":"IM Sch\u00fcler","year":"2014","unstructured":"Sch\u00fcler IM, Hiller M, Roloff T, K\u00fchnisch J, Heinrich-Weltzien R. Clinical success of stainless-steel crowns placed under general anaesthesia in primary molars: an observational follow-up study. J Dent. 2014;42(11):1396\u2013403.","journal-title":"J Dent"},{"issue":"5","key":"8912_CR3","doi-asserted-by":"publisher","first-page":"550","DOI":"10.1111\/ipd.12495","volume":"29","author":"R Midani","year":"2019","unstructured":"Midani R, Splieth CH, Mustafa Ali M, Schmoeckel J, Mourad SM, Santamaria RM. Success rates of preformed metal crowns placed with the modified and standard Hall technique in a paediatric dentistry setting. Int J Paediatr Dent. 2019;29(5):550\u20136.","journal-title":"Int J Paediatr Dent"},{"issue":"5","key":"8912_CR4","first-page":"489","volume":"24","author":"RC Randall","year":"2002","unstructured":"Randall RC. Preformed metal crowns for primary and permanent molar teeth: review of the literature. Pediatr Dent. 2002;24(5):489\u2013500.","journal-title":"Pediatr Dent"},{"issue":"3","key":"8912_CR5","first-page":"198","volume":"18","author":"R Hickel","year":"2005","unstructured":"Hickel R, Kaaden C, Paschos E, Buerkle V, Garc\u00eda-Godoy F, Manhart J. Longevity of occlusally-stressed restorations in posterior primary teeth. Am J Dent. 2005;18(3):198\u2013211.","journal-title":"Am J Dent"},{"issue":"3","key":"8912_CR6","doi-asserted-by":"publisher","first-page":"314","DOI":"10.1111\/ipd.12607","volume":"30","author":"MM Azab","year":"2020","unstructured":"Azab MM, Moheb DM, El Shahawy OI, Rashed MA. Influence of luting cement on the clinical outcomes of zirconia pediatric crowns: a 3-year split-mouth randomized controlled trial. Int J Paediatr Dent. 2020;30(3):314\u201322.","journal-title":"Int J Paediatr Dent"},{"issue":"3","key":"8912_CR7","first-page":"192","volume":"38","author":"DM Holsinger","year":"2016","unstructured":"Holsinger DM, Wells MH, Scarbecz M, Donaldson M. Clinical evaluation and parental satisfaction with pediatric zirconia anterior crowns. Pediatr Dent. 2016;38(3):192\u20137.","journal-title":"Pediatr Dent"},{"issue":"5","key":"8912_CR8","first-page":"385","volume":"41","author":"AL Seminario","year":"2019","unstructured":"Seminario AL, Garcia M, Spiekerman C, Rajanbabu P, Donly KJ, Harbert P. Survival of zirconia crowns in primary maxillary incisors at 12-, 24- and 36-month follow-up. Pediatr Dent. 2019;41(5):385\u201390.","journal-title":"Pediatr Dent"},{"issue":"1","key":"8912_CR9","first-page":"42","volume":"38","author":"L Clark","year":"2016","unstructured":"Clark L, Wells MH, Harris EF, Lou J. Comparison of amount of primary tooth reduction required for anterior and posterior zirconia and stainless-steel crowns. Pediatr Dent. 2016;38(1):42\u20136.","journal-title":"Pediatr Dent"},{"issue":"3","key":"8912_CR10","first-page":"254","volume":"36","author":"AC O'Connell","year":"2014","unstructured":"O\u2019Connell AC, Kratunova E, Leith R. Posterior preveneered stainless-steel crowns: clinical performance after three years. Pediatr Dent. 2014;36(3):254\u20138.","journal-title":"Pediatr Dent"},{"issue":"1","key":"8912_CR11","doi-asserted-by":"publisher","first-page":"393","DOI":"10.1186\/s12903-025-05672-5","volume":"25","author":"NEF Abdou","year":"2025","unstructured":"Abdou NEF, Mohamady EM, Mahmoud T, Abo-Elsoud AAE. Wear resistance and color stability of innovative aesthetic BioFlx crowns compared to zirconia pediatric crowns. BMC Oral Health. 2025;25(1):393.","journal-title":"BMC Oral Health"},{"issue":"1","key":"8912_CR12","doi-asserted-by":"publisher","first-page":"1334","DOI":"10.1186\/s12903-024-05053-4","volume":"24","author":"AAE Abo-Elsoud","year":"2024","unstructured":"Abo-Elsoud AAE, Mohamady EM, FathiAbdou NE. Thermomechanical aging effects on vertical marginal gap and fracture resistance: a comparative study of BioFlx and traditional pediatric crowns. BMC Oral Health. 2024;24(1):1334.","journal-title":"BMC Oral Health"},{"key":"8912_CR13","doi-asserted-by":"publisher","first-page":"587","DOI":"10.1186\/s12903-022-02628-x","volume":"22","author":"OI El Shahawy","year":"2022","unstructured":"El Shahawy OI, Azab MM. Fracture resistance of prefabricated versus custom-made zirconia crowns after thermo-mechanical aging: an in vitro study. BMC Oral Health. 2022;22:587.","journal-title":"BMC Oral Health"},{"issue":"2","key":"8912_CR14","doi-asserted-by":"publisher","first-page":"116","DOI":"10.1111\/jopr.12376","volume":"25","author":"N Nawafleh","year":"2016","unstructured":"Nawafleh N, Hatamleh M, Elshiyab S, Mack F. Lithium disilicate restorations fatigue testing parameters: a systematic review. J Prosthodont. 2016;25(2):116\u201326.","journal-title":"J Prosthodont"},{"issue":"2","key":"8912_CR15","doi-asserted-by":"publisher","first-page":"264","DOI":"10.1016\/j.dental.2020.11.010","volume":"37","author":"A Kessler","year":"2021","unstructured":"Kessler A, Kapor S, Erdelt K, Hickel R, Edelhoff D, Syrek A, et al. Two-body wear and fracture behaviour of an experimental paediatric composite crown in comparison to zirconia and stainless-steel crowns dependent on the cementation mode. Dent Mater. 2021;37(2):264\u201371.","journal-title":"Dent Mater"},{"issue":"6","key":"8912_CR16","doi-asserted-by":"publisher","first-page":"117","DOI":"10.22514\/jocpd.2024.132","volume":"48","author":"T Lath","year":"2024","unstructured":"Lath T, Rathi N, Mehta V, Mopagar VP, Patil RU, Hugar S, et al. Evaluation of stress generation in core build-up material of mutilated primary teeth: a comparative finite element analysis between BioFlx, stainless steel and zirconia crowns. J Clin Pediatr Dent. 2024;48(6):117\u201322.","journal-title":"J Clin Pediatr Dent"},{"issue":"10","key":"8912_CR17","doi-asserted-by":"publisher","first-page":"1281","DOI":"10.3390\/children12101281","volume":"12","author":"SN Al-Haj Ali","year":"2025","unstructured":"Al-Haj Ali SN. BioFlx pediatric crowns: current evidence on clinical outcomes and material properties. Children. 2025;12(10):1281.","journal-title":"Children"},{"issue":"17","key":"8912_CR18","doi-asserted-by":"publisher","first-page":"5308","DOI":"10.3390\/molecules26175308","volume":"26","author":"S Kongkiatkamon","year":"2021","unstructured":"Kongkiatkamon S, Booranasophone K, Tongtaksin A, Kiatthanakorn V, Rokaya D. Comparison of fracture load of four translucent zirconia crowns. Molecules. 2021;26(17):5308.","journal-title":"Molecules"},{"key":"8912_CR19","doi-asserted-by":"publisher","first-page":"295","DOI":"10.1016\/j.jmbbm.2013.09.013","volume":"29","author":"AL Morresi","year":"2014","unstructured":"Morresi AL, D\u2019Amario M, Capogreco M, Gatto R, Marzo G, D\u2019Arcangelo C, et al. Thermal cycling for restorative materials: does a standardized protocol exist in laboratory testing? A literature review. J Mech Behav Biomed Mater. 2014;29:295\u2013308.","journal-title":"J Mech Behav Biomed Mater"},{"issue":"1","key":"8912_CR20","doi-asserted-by":"publisher","first-page":"143","DOI":"10.4103\/jisppd.jisppd_485_24","volume":"43","author":"YJ Kale","year":"2025","unstructured":"Kale YJ, Deshmukh NN, Dadpe MV, Dahake PT, Kendre SB. Evaluation of color stability, wear, and fracture resistance of preformed BioFlx and zirconia crowns: an in vitro study. J Indian Soc Pedod Prev Dent. 2025;43(1):143\u201351.","journal-title":"J Indian Soc Pedod Prev Dent"},{"issue":"3","key":"8912_CR21","first-page":"199","volume":"25","author":"I Krejci","year":"1994","unstructured":"Krejci I, Lutz F, Reimer M. Wear of CAD\/CAM ceramic inlays: restorations, opposing cusps, and luting cements. Quintessence Int. 1994;25(3):199\u2013207.","journal-title":"Quintessence Int"},{"issue":"1","key":"8912_CR22","doi-asserted-by":"publisher","first-page":"343","DOI":"10.1186\/s12903-025-05655-6","volume":"25","author":"NM Metwally","year":"2025","unstructured":"Metwally NM, Elshenawy EA, Elghareb LA. Surface roughness and wear performance of BioFlx versus stainless-steel primary crowns (an in vitro study). BMC Oral Health. 2025;25(1):343.","journal-title":"BMC Oral Health"},{"issue":"1","key":"8912_CR23","doi-asserted-by":"publisher","first-page":"177.e1","DOI":"10.1016\/j.prosdent.2025.02.040","volume":"134","author":"B Ghabchi","year":"2025","unstructured":"Ghabchi B, Mavi F, \u00c7\u00f6mleko\u011flu E, Saklako\u011flu IE, Uzel I. Wear behavior of CAD-CAM zirconia, ceramic and 3D-printed nano-hybrid resin crowns for the restoration of primary and permanent molars: an in vitro study. J Prosthet Dent. 2025;134(1):177.e1-8.","journal-title":"J Prosthet Dent"},{"issue":"5","key":"8912_CR24","doi-asserted-by":"publisher","first-page":"2838","DOI":"10.3390\/ijerph19052838","volume":"19","author":"SD Alzanbaqi","year":"2022","unstructured":"Alzanbaqi SD, Alogaiel RM, Alasmari MA, Al Essa AM, Khogeer LN, Alanazi BS, et al. Zirconia crowns for primary teeth: a systematic review and meta-analyses. Int J Environ Res Public Health. 2022;19(5):2838.","journal-title":"Int J Environ Res Public Health"},{"issue":"21","key":"8912_CR25","doi-asserted-by":"publisher","first-page":"3761","DOI":"10.3390\/polym13213761","volume":"13","author":"SS Abhay","year":"2021","unstructured":"Abhay SS, Ganapathy D, Veeraiyan DN, Ariga P, Heboyan A, Amornvit P, et al. Wear resistance, color stability and displacement resistance of milled PEEK crowns compared to zirconia crowns under simulated chewing and high-performance aging. Polymers (Basel). 2021;13(21):3761.","journal-title":"Polymers (Basel)"},{"issue":"1","key":"8912_CR26","doi-asserted-by":"publisher","first-page":"1438","DOI":"10.1186\/s12903-024-05206-5","volume":"24","author":"DM Amer","year":"2024","unstructured":"Amer DM, Abdellatif AM. In-vivo evaluation of the enamel wear of primary molars against four types of crowns using an intra-oral scanner. BMC Oral Health. 2024;24(1):1438.","journal-title":"BMC Oral Health"},{"issue":"7","key":"8912_CR27","doi-asserted-by":"publisher","first-page":"784","DOI":"10.5005\/jp-journals-10005-3161","volume":"18","author":"P Pareek","year":"2025","unstructured":"Pareek P, Tirupathi S, Kumari K, Afnan L. Antagonistic primary-tooth wear caused by opposing BioFLX, zirconia and stainless-steel crowns: chewing-cycle simulation study. Int J Clin Pediatr Dent. 2025;18(7):784\u201391.","journal-title":"Int J Clin Pediatr Dent"},{"issue":"12","key":"8912_CR28","doi-asserted-by":"publisher","first-page":"1135","DOI":"10.1016\/j.jdent.2013.10.007","volume":"41","author":"Y Zhang","year":"2013","unstructured":"Zhang Y, Sailer I, Lawn BR. Fatigue of dental ceramics. J Dent. 2013;41(12):1135\u201347.","journal-title":"J Dent"},{"issue":"1","key":"8912_CR29","first-page":"77","volume":"9","author":"A Abushanan","year":"2022","unstructured":"Abushanan A, Sharanesha RB, Aljuaid B, Alfaifi T, Aldurayhim A. Fracture resistance of primary zirconia crowns: an in vitro study. Children (Basel). 2022;9(1):77.","journal-title":"Children (Basel)"},{"key":"8912_CR30","doi-asserted-by":"publisher","first-page":"24","DOI":"10.1016\/j.actbio.2019.04.043","volume":"91","author":"F Zhang","year":"2019","unstructured":"Zhang F, Reveron H, Spies BC, Van Meerbeek B, Chevalier J. Trade-off between fracture resistance and translucency of zirconia and lithium-disilicate glass ceramics for monolithic restorations. Acta Biomater. 2019;91:24\u201334.","journal-title":"Acta Biomater"},{"issue":"6","key":"8912_CR31","doi-asserted-by":"publisher","first-page":"721","DOI":"10.1111\/ipd.13171","volume":"34","author":"JE El Hayek","year":"2024","unstructured":"El Hayek JE, Tohme H, Nasr L, El Hachem R, Kabbani N, McHayleh NF. Fracture strength of preformed zirconia crown and CAD\/CAM zirconia, ceramic, and hybrid composite crowns for the restoration of primary molars: an in vitro study. Int J Paediatr Dent. 2024;34(6):721\u20138.","journal-title":"Int J Paediatr Dent"},{"issue":"4","key":"8912_CR32","doi-asserted-by":"publisher","first-page":"427","DOI":"10.1093\/ejo\/cjs021","volume":"35","author":"AI Owais","year":"2013","unstructured":"Owais AI, Shaweesh M, Abu Alhaija ES. Maximum occlusal bite force for children in different dentition stages. Eur J Orthod. 2013;35(4):427\u201333.","journal-title":"Eur J Orthod"},{"issue":"3","key":"8912_CR33","first-page":"39","volume":"47","author":"P Jayakumar","year":"2023","unstructured":"Jayakumar P, FelsyPremila G, Muthu MS, Kirubakaran R, Panchanadikar N, Al-Qassar SS. Bite force of children and adolescents: a systematic review and meta-analysis. J Clin Pediatr Dent. 2023;47(3):39\u201353.","journal-title":"J Clin Pediatr Dent"},{"issue":"4","key":"8912_CR34","doi-asserted-by":"publisher","first-page":"882","DOI":"10.3390\/polym12040882","volume":"12","author":"A Szczesio-Wlodarczyk","year":"2020","unstructured":"Szczesio-Wlodarczyk A, Sokolowski J, Kleczewska J, Bociong K. Ageing of dental composites based on methacrylate resins \u2014 a critical review of the causes and method of assessment. Polymers (Basel). 2020;12(4):882.","journal-title":"Polymers (Basel)"},{"issue":"10","key":"8912_CR35","doi-asserted-by":"publisher","first-page":"6125","DOI":"10.1007\/s00784-023-05229-2","volume":"27","author":"A Refaie","year":"2023","unstructured":"Refaie A, Bourauel C, Fouda AM, Keilig L, Singer L. The effect of cyclic loading on the fracture resistance of 3D-printed and CAD\/CAM milled zirconia crowns \u2014 an in vitro study. Clin Oral Investig. 2023;27(10):6125\u201333.","journal-title":"Clin Oral Investig"},{"key":"8912_CR36","doi-asserted-by":"publisher","first-page":"504","DOI":"10.1016\/j.jmbbm.2018.08.008","volume":"88","author":"JJ Kruzic","year":"2018","unstructured":"Kruzic JJ, Arsecularatne JA, Tanaka CB, Hoffman MJ, Cesar PF. Recent advances in understanding the fatigue and wear behavior of dental composites and ceramics. J Mech Behav Biomed Mater. 2018;88:504\u201333.","journal-title":"J Mech Behav Biomed Mater"}],"container-title":["BMC Oral Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/article\/10.1186\/s12903-026-08912-4","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12903-026-08912-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12903-026-08912-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T12:05:25Z","timestamp":1788782725000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1186\/s12903-026-08912-4"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,23]]},"references-count":36,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,12]]}},"alternative-id":["8912"],"URL":"https:\/\/doi.org\/10.1186\/s12903-026-08912-4","relation":{"has-preprint":[{"id-type":"doi","id":"10.21203\/rs.3.rs-8026149\/v1","asserted-by":"object"}]},"ISSN":["1472-6831"],"issn-type":[{"value":"1472-6831","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,23]]},"assertion":[{"value":"4 November 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"8 June 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"23 June 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"Not applicable. This in vitro study did not involve human participants, human tissue or animals.","order":1,"name":"Ethics","label":"Ethics approval and consent to participate","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"Not applicable.","order":2,"name":"Ethics","label":"Consent for publication","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The authors declare no competing interests.","order":3,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}}],"article-number":"1672"}}