{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:42:29Z","timestamp":1760060549801,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T00:00:00Z","timestamp":1756771200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Compos. Sci."],"abstract":"<jats:p>The purpose of this in silico study was to evaluate the main difference of the adhesion strength of direct and semi-direct composite resin restorations in dentin using micro-tensile testing (\u03bcTBS) and finite element analysis (FEA). This in silico study employed cohesive zone traction and shear laws to investigate interfacial damage in both restoration groups. Tridimensional finite element models of both restoration specimens were created. A 20 \u03bcm thick resin cement layer was created for the semi-direct case. The Clearfil SE Bond 2 adhesive system and the restorative material, Ceram X Spectra ST HV composite resin, were used on both restorations. The numerical bond strength of both restoration techniques was evaluated using two different analysis assumptions. In the first assumption, the numerical analysis procedure included only the non-linear behavior of dentin and the von Mises damage criterion, whereas cohesive zone models were included in the second analysis assumption. The influence of dentin-adhesive cohesive mechanical properties was studied using values reported in the literature, and a sensitivity study helped improve the correlation between experimental and numerical results. The mechanical properties of the composite cohesive zone were defined assuming that the interface strength of dentin and composite follows the values reported by the manufacturer of Spectra ST. Damage initiation and progression were analyzed, and strains and stresses of the cohesive zone models (CZM) were compared with the corresponding perfect bonded models. The experimental \u00b5TBS results for the direct restoration strategy showed an adhesive strength of 38.156 \u00b1 10.750 MPa, while the CZM predicted a slightly higher value of 40.4 \u00b1 10.8 MPa. For the indirect restoration strategy, the experimental adhesive strength was 25.449 \u00b1 10.193 MPa, compared to a numerically predicted strength of 28.1 \u00b1 9.3 MPa. Overall, the CZM tends to overestimate the adhesive strength relative to experimental values. The statistical analysis of dentin extension strains for direct (DR) and semi-direct (SR) group models reveals that the SR configuration yields higher strain levels. Hence, these results suggest that, assuming identical dentin properties across both restoration groups, the material configuration in the direct restoration offers better mechanical protection to the dentin. These findings highlight the critical role of incorporating damage mechanics to more accurately characterize stress distribution during tooth rehabilitation.<\/jats:p>","DOI":"10.3390\/jcs9090475","type":"journal-article","created":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T15:02:57Z","timestamp":1756825377000},"page":"475","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Microtensile Bond Strength of Composite Restorations: Direct vs. Indirect Techniques Using Cohesive Zone Models"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3030-0146","authenticated-orcid":false,"given":"Maria A.","family":"Neto","sequence":"first","affiliation":[{"name":"University of Coimbra, Center for Mechanical Engineering, Materials and Processes (CEMMPRE-ARISE), Department of Mechanical Engineering, 3030-788 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2471-1125","authenticated-orcid":false,"given":"Ricardo","family":"Branco","sequence":"additional","affiliation":[{"name":"University of Coimbra, Center for Mechanical Engineering, Materials and Processes (CEMMPRE-ARISE), Department of Mechanical Engineering, 3030-788 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5237-0773","authenticated-orcid":false,"given":"Ana M.","family":"Amaro","sequence":"additional","affiliation":[{"name":"University of Coimbra, Center for Mechanical Engineering, Materials and Processes (CEMMPRE-ARISE), Department of Mechanical Engineering, 3030-788 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4019-9379","authenticated-orcid":false,"given":"Ana","family":"Messias","sequence":"additional","affiliation":[{"name":"University of Coimbra, Center for Innovation and Research in Oral Sciences (CIROS), Faculty of Medicine, 3000-075 Coimbra, Portugal"},{"name":"University of Coimbra, Institute Prosthodontics and Implant Dentistry, Faculty of Medicine, 3000-075 Coimbra, Portugal"},{"name":"University of Coimbra, Center for Mechanical Engineering, Materials and Processes (CEMMPRE-ARISE), Department of Dentistry, 3030-788 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1038\/s41432-024-01095-3","article-title":"Efficacy of different adhesive systems in bonding direct resin composite restorations: A systematic review and meta-analysis","volume":"26","author":"Saini","year":"2025","journal-title":"Evid. Based Dent."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Bourgi, R., Kharouf, N., Cuevas-Su\u00e1rez, C.E., Lukomska-Szymanska, M., Haikel, Y., and Hardan, L. (2024). A Literature Review of Adhesive Systems in Dentistry: Key Components and Their Clinical Applications. Appl. Sci., 14.","DOI":"10.3390\/app14188111"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.dental.2010.10.016","article-title":"State of the art etch-and-rinse adhesives","volume":"27","author":"Pashley","year":"2011","journal-title":"Dent. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1016\/j.prosdent.2021.11.009","article-title":"Clinical performance of direct composite resin versus indirect restorations on endodontically treated posterior teeth: A systematic review and meta-analysis","volume":"130","author":"Cune","year":"2023","journal-title":"J. Prosthet. Dent."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Incekara, M.S., and Karadas, M. (2025). Clinical comparison of direct and indirect class II composite restorations: A prospective 12-month follow-up study. BMC Oral Health, 25.","DOI":"10.1186\/s12903-025-06604-z"},{"key":"ref_6","unstructured":"Mgbatou, S.A.N. (2022). Finite Element Analysis of Dental Restorative Adhesives. [Master\u2019s Thesis, Politecnico di Torin]."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1086","DOI":"10.1016\/j.dental.2006.10.002","article-title":"Shear versus micro-shear bond strength test: A finite element stress analysis","volume":"23","author":"Placido","year":"2007","journal-title":"Dent. Mater."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e238","DOI":"10.1016\/j.dental.2016.07.005","article-title":"A new concept and finite-element study on dental bond strength tests","volume":"32","author":"Jin","year":"2016","journal-title":"Dent. Mater."},{"key":"ref_9","first-page":"182","article-title":"Reliability of an Innovative Slab Shear versus Microtensile Bond Strength Test: Mechanical and Finite Element Analysis","volume":"18","author":"Abdou","year":"2023","journal-title":"Eur. J. Dent."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Babaei, B., Shouha, P., Birman, V., Farrar, P., Prentice, L., and Prusty, G. (2022). The effect of dental restoration geometry and material properties on biomechanical behaviour of a treated molar tooth: A 3D finite element analysis. J. Mech. Behav. Biomed. Mater., 125.","DOI":"10.1016\/j.jmbbm.2021.104892"},{"key":"ref_11","first-page":"1872","article-title":"Finite element analysis on mechanical performance of amalgam, gold, and bioglass dental filling materials in molar tooth","volume":"12","author":"Nor","year":"2023","journal-title":"Mater. Today Proc."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1267","DOI":"10.1016\/j.dental.2024.06.007","article-title":"Functionally graded bi-material interface for Porcelain Veneered Zirconia dental crowns: A study using viscoelastic finite element analysis","volume":"40","author":"Shrestha","year":"2024","journal-title":"Dent. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Neto, M.A., Roseiro, L., Messias, A., Falacho, R.I., Palma, P.J., and Amaro, A.M. (2021). Influence of cavity geometry on the fracture strength of dental restorations: Finite element study. Appl. Sci., 11.","DOI":"10.3390\/app11094218"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1016\/j.jds.2024.05.033","article-title":"Elucidating interfacial failure of cervical restorations using damage mechanics: A finite element analysis","volume":"20","author":"Tseng","year":"2025","journal-title":"J. Dent. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Palma, P.J., Neto, M.A., Messias, A., and Amaro, A.M. (2025). Microtensile Bond Strength of Composite Restorations: Direct vs. Semidirect Technique Using the Same Adhesive System. J. Compos. Sci., 9.","DOI":"10.3390\/jcs9050203"},{"key":"ref_16","first-page":"57","article-title":"Film Thickness and Flow Properties of Resin-Based Cements at Different Temperatures","volume":"14","author":"Bagheri","year":"2013","journal-title":"J. Dent."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Tribst, J.P.M., dos Santos, A.F.C., da Cruz Santos, G., da Silva Leite, L.S., Lozada, J.C., Silva-Conc\u00edlio, L.R., Baroudi, K., and Amaral, M. (2021). Effect of Cement Layer Thickness on the Immediate and Long-Term Bond Strength and Residual Stress between Lithium Disilicate Glass-Ceramic and Human Dentin. Materials, 14.","DOI":"10.3390\/ma14185153"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1111\/jerd.12851","article-title":"Luting indirect restorations with resin cements versus composite resins: Effects of preheating and ultrasound energy on film thickness","volume":"34","author":"Falacho","year":"2022","journal-title":"J. Esthet. Restor. Dent."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.1016\/j.prosdent.2022.08.024","article-title":"Impact of in vitro findings on clinical protocols for the adhesion of CAD-CAM blocks: A systematic integrative review and meta-analysis","volume":"131","author":"Carbas","year":"2024","journal-title":"J. Prosthet. Dent."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"478","DOI":"10.1016\/j.jmbbm.2008.12.002","article-title":"Fractography and fracture toughness of human dentin","volume":"2","author":"Yan","year":"2009","journal-title":"J. Mech. Behav. Biomed. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1177\/154411130301400103","article-title":"The mechanical properties of human dentin: A critical review and re-evaluation of the dental literature","volume":"14","author":"Kinney","year":"2003","journal-title":"Crit. Rev. Oral Biol. Med."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Chowdhury, A.F.M.A., Alam, A., Islam, M.D.R.R., Yamauti, M., Alam, M.S., Rahman, M.M., Ahmed, M., \u00c1lvarez-Lloret, P., and Sano, H. (2021). The Influences of Dehydration on the Mechanical Properties of Human Dentin. Minerals, 11.","DOI":"10.3390\/min11040336"},{"key":"ref_23","unstructured":"Sirona, D. (2025, August 12). Scientific Manual Spectra ST Composites. Available online: https:\/\/www.dentsplysirona.com\/content\/dam\/master\/product-procedure-brand-categories\/restorative\/product-categories\/direct-restoration\/composites-flowables\/universal-composites\/ceram-x-spectra-st\/scientific-support-clinical-education\/RES-Scientific-Manual-Spectra-ST-Composites-EN.pdf.coredownload.pdf."},{"key":"ref_24","unstructured":"Ivoclar Vivadent AG. (2014). Scientific Documentation Variolink Esthetic, Ivoclar Vivadent AG."},{"key":"ref_25","unstructured":"Kuraray Noritake Dental Inc. (2024). Clearfil SE Bond 2 Scientific Product Information, Kuraray Noritake Dental Inc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"677","DOI":"10.1177\/00220345860650050901","article-title":"Fracture toughness of human dentin","volume":"65","author":"Watts","year":"1986","journal-title":"J. Dent. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1505","DOI":"10.21608\/edj.2021.58301.1454","article-title":"Fracture toughness of different adhesive\/dentin interfaces analyzed by finite element stress analysis","volume":"67","author":"Mustafa","year":"2021","journal-title":"Egypt. Dent. J."},{"key":"ref_28","first-page":"309","article-title":"Tensile Strength of Human Dentin as a function of tubule Orientation and Density","volume":"3","author":"Carvalho","year":"2001","journal-title":"J. Adhes. Dent."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/j.matlet.2016.04.211","article-title":"The strength properties of human dentinoenamel junction","volume":"178","author":"Zaytsev","year":"2016","journal-title":"Mater. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1016\/j.tafmec.2018.05.006","article-title":"Taper\u2019s angle influence on the structural integrity of single-lap bonded joints","volume":"96","author":"Amaro","year":"2018","journal-title":"Theor. Appl. Fract. Mech."}],"container-title":["Journal of Composites Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2504-477X\/9\/9\/475\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:38:18Z","timestamp":1760035098000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2504-477X\/9\/9\/475"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,2]]},"references-count":30,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["jcs9090475"],"URL":"https:\/\/doi.org\/10.3390\/jcs9090475","relation":{},"ISSN":["2504-477X"],"issn-type":[{"type":"electronic","value":"2504-477X"}],"subject":[],"published":{"date-parts":[[2025,9,2]]}}}