d e n t a l m a t e r i a l s 2 8 ( 2 0 1 2 ) 327–339 Available online at www.sciencedirect.com jo u rn al hom epa ge : www.intl.elsevierhealth.com/journals/dema Effects of resinous monomers on the odontogenic differentiation and mineralization potential of highly proliferative and clonogenic cultured apical papilla stem cells Athina Bakopoulou a,b , Gabriele Leyhausen b , Joachim Volk b , Petros Koidis a , Werner Geurtsen b,∗,1 a Department of Fixed Prosthesis & Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece b Department of Conservative Dentistry, Periodontology & Preventive Dentistry, School of Dentistry, Hannover Medical School, Hannover D-30625, Germany a r t i c l e i n f o Article history: Received 29 September 2011 Received in revised form 1 December 2011 Accepted 4 January 2012 Keywords: Resinous monomers Biomineralization Dental pulp repair Odontogenic differentiation Apical papilla stem cells a b s t r a c t Objective. The aim of this study was to investigate the effects of resinous monomers on the odontogenic differentiation and mineralization potential of apical papilla stem cells (SCAP). Methods. Cultures were established from developing third molars of healthy donors aged 14–18 years-old and were extensively characterized for proliferation rate, colony form- ing unit efficiency and expression of stem cell markers (STRO-1, CD146, CD34, CD45, CD105, CD117-c-Kit, CD24, CD90, Nanog, Oct3/4), in order to select those with enhanced stem cell and odontogenic differentiation properties. SCAP enriched cultures were then induced for odontogenic differentiation in the continuous presence of low concentrations (0.05–0.5 mM) of the monomers 2-hydroxy-ethyl-methacrylate-HEMA and triethylene- glycol-dimethacrylate-TEGDMA for 3 weeks (long-term exposure). Additionally, the effects of a single exposure (72 h) to higher concentrations of HEMA (2 mM) and TEGDMA (1 mM) were evaluated. Results. The results showed that both types of monomer-exposure significantly delayed the odontogenic differentiation and mineralization processes of SCAP cells. A down- regulation followed by recovery in the expression of differentiation markers, including dentin sialophosphoprotein-DSPP, bone sialoprotein-BSP, osteocalcin-OCN and alkaline phosphatase-ALP was recorded. This was accompanied by reduction of the mineralized matrix produced by monomer-treated-compared to non-treated contol cultures. Further- more, a concentration-dependence was observed for both monomers during long-term exposure, whereas the effects of HEMA were evident at much lower concentrations com- pared to TEGDMA. ∗ Corresponding author at: Department of Conservative Dentistry, Periodontology and Preventive Dentistry, School of Dentistry, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany. Tel.: +49 0511 532 4815, fax: +49 0511 532 4811. E-mail address: Geurtsen.Werner@mh-hannover.de (W. Geurtsen). 1 Address: Affiliate Professor of Restorative Dentistry, University of Washington, Seattle, USA. 0109-5641/$ – see front matter © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2012.01.002