dental materials 25 ( 2 0 0 9 ) 1576–1584 available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/dema Inﬂuence of curing protocol on selected properties of light-curing polymers: Degree of conversion, volume contraction, elastic modulus, and glass transition temperature Magali Dewaele a,b,* , Erik Asmussen c , Anne Peutzfeldt c , E. Christian Munksgaard c , Ana R. Benetti d , Gauthier Finné a , Gaëtane Leloup e , Jacques Devaux a a Laboratory of Chemistry and Physics of High Polymers, Université catholique de Louvain, Louvain-la-Neuve, Belgium b Department of Prosthodontics, School of Dentistry and Stomatology, Université catholique de Louvain, Brussels, Belgium c Department of Dental Materials, School of Dentistry, University of Copenhagen, Copenhagen, Denmark d Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru SP, Brazil e Department of Operative Dentistry, School of Dentistry and Stomatology, Université catholique de Louvain, Brussels, Belgium article info Article history: Received 28 October 2008 Received in revised form 3 August 2009 Accepted 4 August 2009 Keywords: Light-curing Soft-start Degree of conversion Volume contraction Elastic modulus Glass transition temperature Dental materials Dental polymers Resin composite abstract Objectives. The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T g ) as measured on a model polymer. It was a further aim to correlate the measured values with each other. Methods. Different light-curing protocols were used in order to investigate the inﬂuence of energy density (ED), power density (PD), and mode of cure on the properties. The modes of cure were continuous, pulse-delay, and stepped irradiation. DC was measured by Raman micro-spectroscopy. C was determined by pycnometry and a density column. E was mea- sured by a dynamic mechanical analyzer (DMA), and T g was measured by differential scanning calorimetry (DSC). Data were submitted to two- and three-way ANOVA, and linear regression analyses. Results. ED, PD, and mode of cure inﬂuenced DC, C, E, and T g of the polymer. A signiﬁcant positive correlation was found between ED and DC (r = 0.58), ED and E (r = 0.51), and ED and T g (r = 0.44). Taken together, ED and PD were signiﬁcantly related to DC and E. The regression coefﬁcient was positive for ED and negative for PD. Signiﬁcant positive correlations were detected between DC and C (r = 0.54), DC and E (r = 0.61), and DC and T g (r = 0.53). Comparisons between continuous and pulse-delay modes of cure showed signiﬁcant inﬂuence of mode of cure: pulse-delay curing resulted in decreased DC, decreased C, and decreased T g . Inﬂuence of mode of cure, when comparing continuous and step modes of cure, was more ambiguous. ∗ Corresponding author at: Cliniques universitaires St-Luc, Ecole de médecine dentaire et de stomatologie, avenue Hippocrate 10/bte5732, 1200 Bruxelles, Belgium. Fax: +32 2 764 90 62. E-mail address: Magali.Dewaele@uclouvain.be (M. Dewaele). 0109-5641/$ – see front matter © 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2009.08.001