Effect of hydrogen peroxide on the three-dimensional polymer network in composites

Objectives. Less data are available about the effects of hydrogen peroxide on the three-dimensional polymer network of polymerized composites. Therefore the study was performed to test the effects of hydrogen peroxide on the three-dimensional polymer network in composites. Methods. Polymerized specimens from Tetric Flow (R), Tetric Ceram (R) and Filtek (TM) Supreme XT were bleached with Opalescence (R) PF 15% for 5 h or PF 35% for 0.5 h, respectively, and then stored in methanol for 1 d and 7 d. Controls were unbleached specimens. The eluates were analyzed by gas chromatography/mass spectrometry. Results. More methacrylic acid (MAA), bisphenol-A (BPA), ethoxylated bisphenol-A-dimethacrylate (BisEMA), hydroquinone monomethyl ether (HQME), 1,10-decanediol dimethacrylate (DDDMA) and/or triethylene glycol dimethacrylate (TEGDMA) were eluted from bleached specimens compared with non bleached controls (1 d). The highest DDDMA amount of 419.8 mu mol/l was found in the eluates after 7 d in Tetric Flow (R) specimens treated with PF 15. The highest HQME amount of 159.6 mu mol/l was found in eluates from Tetric Ceram (R) specimens treated with PF after 7 d. The highest TEGDMA amount of 178.7 mu mol/l was found in eluates from Filtek (TM) Supreme XT specimens treated with PF 35 after 7 d. Significance. Bleaching with hydrogen peroxide has an effect on the three-dimensional polymer network in polymerized composites leading to an increase in the release of unpolymerized monomers, additives and unspecific oxidative products. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.