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Water Transport in Resin-modified Glass-ionomer Dental Cement
1 Department of Chemistry, IUT Bethune, University of Artois 1230 rue de l’Université, 62408 Bethune, France
* To whom correspondence should be addressed.
Water uptake and water loss have been studied in a commercial resin-modified glass-ionomer cement, Fuji II LC, under a variety of conditions. Uptake was generally non-Fickian, but affected by temperature. At room temperature, the equilibrium water uptake values varied from 2.47 to 2.78% whereas at low temperature (12°C), it varied from 0.85 to 1.18%. Cure time affected uptake values significantly. Water uptake was much lower than in conventional glass-ionomer restorative cements exposed to water vapor. Loss of water under desiccating conditions was found to be Fickian for the first 5 h loss at both 22 and 12°C. Diffusion coefficients were between 0.45 and 0.76 x 10-7 cm2/s, with low temperature diffusion coefficients slightly greater than those at room temperature. Plotting water loss as percentage versus s- Key Words: resin-modified glass-ionomer, water sorption, water loss, kinetics.
First published on July 30, 2008, doi:10.1177/0885328208088863 |
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allowed activation energies to be determined from the Arrhenius equation and these were found to be 65.6, 79.8, and 7.7 kJ/mol respectively for 30, 20, and 10 s cure times. The overall conclusion is that the main advantage of incorporating HEMA into resin-modified-glass-ionomers is to alter water loss behavior. Rate of water loss and total amount lost are both reduced. Hence, resin-modified glass-ionomers are less sensitive to water loss than conventional glass-ionomers.