Bonding of an auto-adhesive luting material to enamel and dentin Jan De Munck a , Marcos Vargas b , Kirsten Van Landuyt a , Kazuhiro Hikita a,c , Paul Lambrechts a , Bart Van Meerbeek a, * a Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, Leuven 3000, Belgium b Department of Operative Dentistry, University of Iowa, Iowa city, IA, USA c Institute of Medical Science, Health Sciences University of Hokkaido, Sapporo, Japan Received 14 October 2003; received in revised form 2 February 2004; accepted 1 March 2004 KEYWORDS Adhesion; Cement; Self- adhesive; Micro-tensile bond strength; Fe-SEM; TEM Summary Objectives: The objectives of this study were (1) to assess the bonding performance of a new auto-adhesive cement (RelyX Unicem, 3M ESPE) to enamel and dentin, using a standard micro-tensile bond strength (mTBS) test set-up, and (2) to evaluate the interaction of this material with dentin by means of high-resolution electron microscopy. Methods: The mTBS of RelyX Unicem with and without prior acid etching was determined to enamel and dentin after 24 h of water storage and compared to the bonding effectiveness of the control cement (Panavia-F, Kuraray). In addition, diamond-knife cut interfaces of RelyX Unicem and Panavia-F bonded to dentin were examined using field-emission scanning (Fe-SEM) and transmission electron microscopy (TEM). Results: The mTBS of RelyX Unicem to enamel was significantly lower than that of the control cement, whereas no significant difference was found when both cements were bonded to dentin. Acid etching prior to the application of RelyX Unicem raised the enamel mTBS to the same level as that of the control, but was detrimental for the dentin bonding effectiveness. The latter must be attributed to inadequate infiltration of the collagen mesh as revealed by Fe-SEM and TEM. Morphological evaluation additionally revealed that RelyX Unicem only superficially interacted with enamel and dentin, and that application using some pressure is required to ensure close adaptation of the cement to the cavity wall. Significance: (1) RelyX Unicem should always be applied with some pressure, to ensure that the relatively high viscous cement intimately adapts to the cavity wall; (2) The cement only interacted superficially with dentin and enamel; (3) The best bonding effectiveness with this new auto-adhesive cement was obtained by selectively acid-etching enamel prior to luting. Q 2004 Published by Elsevier Ltd on behalf of Academy of Dental Materials. All rights reserved. 0109-5641/$ - see front matter Q 2004 Published by Elsevier Ltd on behalf of Academy of Dental Materials. All rights reserved. doi:10.1016/j.dental.2004.03.002 Dental Materials (2004) xx, xxx–xxx www.intl.elsevierhealth.com/journals/dema *Corresponding author. Tel.: þ32-16-33-75-87; fax: þ32-16- 33-27-52. E-mail address: bart.vanmeerbeek@med.kuleuven.ac.be ARTICLE IN PRESS