Please cite this article in press as: Aboushelib MN, et al. Innovations in bonding to zirconia-based materials. Part II: Focusing on chemical interactions. Dent Mater (2009), doi:10.1016/j.dental.2009.02.011 ARTICLE IN PRESS DENTAL-1469; No. of Pages 5 dental materials xxx ( 2 0 0 9 ) xxx–xxx available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/dema Innovations in bonding to zirconia-based materials. Part II: Focusing on chemical interactions Moustafa N. Aboushelib a,b , Hesam Mirmohamadi a , Jukka P. Matinlinna c,d,∗ , Edwin Kukk e , Hani F. Ounsi f , Ziad Salameh f,g a Department of Dental Materials Science, Academic Center for Dentistry Amsterdam (ACTA), The Netherlands b Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Egypt c Nordic Institute of Dental Materials (NIOM), Haslum, Norway d Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku, Finland e Department of Physics, University of Turku, Finland f Research Department, School of Dentistry, Lebanese University, Lebanon g Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Saudi Arabia article info Article history: Received 9 May 2008 Accepted 23 February 2009 Keywords: Zirconia Primers Microtensile bond strength Dental cements Silanes abstract Objectives. The zirconia–resin bond strength was enhanced using novel engineered zirco- nia primers in combination with selective infiltration etching as a surface pre-treatment. The aim of this study was to evaluate the effect of artificial aging on the chemical sta- bility of the established bond and to understand the activation mechanism of the used primers. Methods. Selective infiltration etched zirconia discs (Procera; NobelBiocare) were coated with one of four novel engineered zirconia primers containing reactive monomers and were bonded to resin-composite discs (Panavia F2.0). Fourier transform infrared spectroscopy (FT- IR) was carried out to examine the chemical activation of zirconia primers from mixing time and up to 60 min. The bilayered specimens were cut into microbars (1 mm 2 in cross-section area) and zirconia–resin microtensile bond strength (MTBS) was evaluated immediately and after 90 days of water storage at 37 ◦ C. Scanning electron microscopy (SEM) was used to analyze the fracture surface. Results. There was a significant drop in MTBS values after 90 days of water storage for all tested zirconia primers from ca. 28–41 MPa to ca. 15–18 MPa after completion of artificial aging. SEM revealed increase in percentage of interfacial failure after water storage. FTIR spectra suggested adequate activation of the experimental zirconia primers within 1 h of mixing time. Significance. The novel engineered zirconia primers produced initially high bond strength val- ues which were significantly reduced after water storage. Long-term bond stability requires developing more stable primers. © 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. ∗ Corresponding author at: University of Hong Kong, Faculty of Dentistry, Dental Materials Science, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong, PR China. Tel.: +852 2859 0304; fax: +852 2548 9464. E-mail address: jpmat@hku.hk (J.P. Matinlinna). 0109-5641/$ – see front matter © 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2009.02.011