d e n t a l m a t e r i a l s 3 0 ( 2 0 1 4 ) 945–953 Available online at www.sciencedirect.com ScienceDirect jo ur nal home p ag e: www.intl.elsevierhealth.com/journals/dema BAPO as an alternative photoinitiator for the radical polymerization of dental resins Carine T.W. Meereis a , Fernanda B. Leal a , Giana S. Lima b , Rodrigo V. de Carvalho c , Evandro Piva a , Fabrício A. Ogliari a,d,* a Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil b Dentistry Course, University Center of Várzea Grande, Várzea Grande, MT, Brazil c School of Dentistry, University of North of Paraná, Londrina, PR, Brazil d School of Materials Engineering, Federal University of Pelotas, Pelotas, RS, Brazil a r t i c l e i n f o Article history: Received 25 June 2013 Received in revised form 30 October 2013 Accepted 21 May 2014 Keywords: Photoinitiator Oxide bisacylphosphine Phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide Diphenyliodonium hexafluorophosphate Camphorquinone Polymerization kinetics Flexural strength Elastic modulus Dental resins a b s t r a c t Objectives. This study evaluated the performance of phenylbis (2,4,6-trimethylbenzoyl)- phosphine oxide (BAPO) as an alternative photoinitiator in the polymerization kinetics (PK), flexural strength () and elastic modulus (E) of a model dental resin. Methods. A monomer mixture based on Bis-GMA and TEGDMA was used as model den- tal resin. Initially a screening was performed to evaluate BAPO concentrations (0.125, 0.25, 0.50, 1, 2, and 4 mol%). Photoinitiator systems were formed with the combina- tion of camphorquinone (CQ), ethyl-dimethylamino benzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), and BAPO. Groups with unitary photoinitiator sys- tems (BAPO and CQ), binary (BAPO + EDAB, BAPO + DPIHFP and CQ + EDAB), ternary (BAPO + CQ + EDAB, BAPO + CQ + DPIHFP, BAPO + EDAB + DPIHFP and CQ + EDAB + DPIHFP) and quaternary (BAPO + CQ + EDAB + DPIHFP) were formulated for evaluation. Real-time Fourier transform infrared spectroscopy was used to investigate the PK and test mini-bending to evaluate  and E. Results. When only CQ was used, a slow polymerization reaction was observed and a lower monomer conversion. When only BAPO was used as photoinitiator an increase in the poly- merization rate was observed and conversion was higher than CQ + EDAB. The ternary system (BAPO + EDAB + DPIHFP) showed the highest polymerization and conversion rate, in short photo-activation time. Significance. BAPO it is a potential photoinitiator for the photopolymerization of dental mate- rials. © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. ∗ Corresponding author at: Biomaterials Development and Control Center (CDC-Bio), School of Dentistry, Federal University of Pelotas, Rua Gonc ¸ alves Chaves, 457, Pelotas CEP 96015-560, RS, Brazil. Tel.: +55 53 32283705; fax: +55 53 32283705. E-mail address: ogliari@gmail.com (F.A. Ogliari). http://dx.doi.org/10.1016/j.dental.2014.05.020 0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.