Effect of polyacid aqueous solutions on photocuring of polymerizable
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Effect of polyacid aqueous solutions on
Effect of polyacid aqueous solutions on photocuring of polymerizable components of resin-modified glass ionomer cements Ewa Andrzejewska*, Maciej Andrzejewski, Elzbieta Socha, Dorota Zych-Tomkowiak Institute of Chemical Technology and Engineering, Poznan University of Technology, Pl. M. Sklodowskiej-Curie 2, 60-965 Poznan, Poland Received 7 August 2001; revised 20 February 2002; accepted 13 June 2002 Abstract Objectives . Resin-modified glass ionomer cements (RMGI) are hybrid materials prepared by incorporation of polymerizable components (typically 2-hydroxyethyl methacrylate (HEMA) with possible addition of multifunctional methacrylates) into a conventional acid – base mixture (a polymeric acid with powdered calcium fluoro-aluminosilicate glasses). During setting, the photopolymerization process and the acid – base reaction affect each other. The aim of this work was to examine the effect of a 45% aqueous solution of poly(acrylic acid) (PAA) and the liquid component of a commercial glass ionomer cement on HEMA and triethyleneglycol dimethacrylate (TEGDMA) photopolymerization. Methods . The polymerization was initiated by 2,2-dimethoxy-2-phenylacetophenone (DMPA) and camphorquinone (CQ)/coinitiator system. The reaction course was monitored under Ar and air by isothermal differential scanning calorimetry. Results . The main effect of addition of polyacid solution (PAA and commercial) up to 10 wt% to HEMA on the polymerization initiated with DMPA was earlier onset of autoacceleration. For the process initiated by the CQ-based system, the addition of 5 wt% of PAA solution strongly accelerated the polymerization and increased the conversion, both in Ar atmosphere as well as in air. TEGDMA photopolymerization was not influenced or slightly retarded by the presence of 3 wt% of PAA solution (the upper limit of solubility), depending on the initiating system used. Significance . Under initiation conditions used in curing of commercial dental products (CQ-based two component initiating system), the presence of polyacid-aqueous solution in HEMA-based photocurable component increases markedly the polymerization rate and the conversion both in Ar atmosphere as well as in air. This result contributes to a characterization of the setting process of RMGIs. q 2003 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved. Keywords: Resin-modified glass ionomer cements; Photocuring; 2-Hydroxyethyl methacrylate; Triethyleneglycol dimethacrylate; Effect of polyacids 1. Introduction Glass ionomer cements are acid – base cements whose setting reaction involves neutralization of acid groups on polymeric acids, like poly(acrylic acid) (PAA), with powdered solid bases (calcium fluoro-aluminosilicate glasses). These glasses are bases in the sense that they are proton acceptors, even though they are not soluble in water [1] . The polymer is used typically as a 40 – 50% aqueous solution [2] . Resin-modified glass ionomer cements (RMGIs) are hybrid materials prepared by incorporation of polymeriz- able components into a conventional acid – base mixture [2] . Typically 2-hydroxyethyl methacrylate (HEMA) is used with possible addition of multifunctional methacrylates. HEMA is a monovinyl monomer commonly used in adhesive chemistry as a hydrophilic primer and as a component of some adhesive resins [3] . In RMGIs it makes the aqueous and the organic components miscible acting both as a co-solvent and a polymerizable monomer. The role of multifunctional methacrylates is to introduce 0109-5641/03/$ - see front matter q 2003 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved. doi:10.1016/S0109-5641(02)00096-9 Dental Materials 19 (2003) 501–509 www.elsevier.com/locate/dental * Corresponding author. Tel.: þ48-61-665-3637; fax: þ48-61-665-3649. Download 222.27 Kb. Do'stlaringiz bilan baham: |
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