dental materials 24 ( 2 0 0 8 ) 362–371 available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/dema The induction of oxidative stress, cytotoxicity, and genotoxicity by dental adhesives M. Demirci a , K.-A. Hiller b , C. Bosl b , K. Galler b , G. Schmalz b , H. Schweikl b,∗ a Department of Conservative Dentistry, Faculty of Dentistry, Istanbul University, C ¸ apa, Istanbul 34390, Turkey b Department of Operative Dentistry and Periodontology, University of Regensburg, 93042 Regensburg, Germany article info Article history: Received 22 February 2007 Accepted 8 June 2007 Keywords: Dental adhesives Cytotoxicity Genotoxicity Reactive oxygen species abstract Objectives. Polymerized dental resin materials release residual monomers that may inter- act with pulp tissues. We hypothesized that dental adhesives might cause cytotoxicity in pulp cells via the generation of reactive oxygen species (ROS), which may also contribute to genotoxic effects in vitro. Methods. For cytotoxicity testing, transformed human pulp-derived cells were exposed to extracts of primers and bonding agents of Clearfil SE bond, Clearfil Protect bond, AdheSE, Prompt L-Pop, and Excite for 24h. The cytotoxicity of the same materials was also analyzed in a dentin barrier test device using three-dimensional pulp cell cultures. The generation of ROS in monolayer cultures was measured after a 1h exposure period by flow cytometry (FACS), and genotoxicity as indicated by the formation of micronuclei was determined in V79 cells after a 24 h exposure period. Results. The dentin primers and bonding agents decrease cell survival in a dose-related man- ner. Cytotoxicity of bonding agents based on concentrations which caused 50% cell death (EC50) were ranked as follows: Excite (0.16 mg/ml) > AdheSE bond (0.30 mg/ml) > Clearfil Pro- tect bond (0.35 mg/ml) > Clearfil SE bond (0.37 mg/ml), and Prompt L-Pop bond (0.68 mg/ml). Dentin primers were about 10-fold less effective. In contrast, no cytotoxic effects of the dental adhesives were observed in a dentin barrier test device. Yet, all dental adhesives increased the amounts of ROS about fivefold in pulp cells in a dose-related manner, and, again, the bonding agents were more efficient than the dentin primers. Finally, the number of micronuclei was increased about sixfold by extracts of the AdheSE primer. Significance. Our results suggest that the cytotoxic potencies demonstrated by these materials might be of clinical relevance, since all dental adhesives disturbed the cellular redox state of pulp cells in monolayer cultures. As a result, the concentrations of biologically active ingredients of some of the agents may be high enough to modify pulp cell metabolism when the materials are used in deep cavities or directly contact pulp tissue. © 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. 1. Introduction Modern dental adhesive systems are used to improve the con- tact between the restorative material and the walls of the prepared cavity of the tooth. As these materials come in close ∗ Corresponding author. Tel.: +49 941 944 6142; fax: +49 941 944 6025. E-mail address: helmut.schweikl@klinik.uni-regensburg.de (H. Schweikl). and prolonged contact with vital dentin, their influence on pulp tissue is critical. Thus, the biocompatibility of dentin bonding agents is a relevant aspect of the clinical success of these materials [1–4]. Dentin bonding agents alone proved to be cytotoxic, and it has been found that the type and 0109-5641/$ – see front matter © 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2007.06.009