Glass-Ionomer Cement and Resin-modified Glass-Ionomer Water Content Thermal Analysis

Objectives: To analyze the GIC and RMGI retained water characteristics over time using thermogravimetric (TGA) thermal analysis.
Methods: Both a conventional GIC (Fuji Equia) and a RMGI (Fuji II LC) were prepared following manufacturer recommendations with each material placed into 40 µl aluminum DSC crucibles (n=12) and stored in a 98% humid PBS environment at 37C. Samples were analyzed with a combined TGA/DSC unit (Mettler Toledo TGA/DSC1) over a 25-620C temperature scan. The integrated thermal enthalpy was divided by the water weight loss to determine the enthalpy required to remove 1g of water. Samples were tested immediately after mixing, and then at 24h,1w, and then 1m,3m,6m,9m,12m,18m, and 24m after fabrication. Mean data was analyzed with Kruskal-Wallis/Dunn’s p=0.05.
Results: Results are listed in the table. As time progressed, it required more energy to remove water per gram. It required significantly more energy to remove water from Fuji Equia after 6 months and after 3 months for Fuji II LC.
Conclusions: Water starts to become more firmly bound at 6 months for Fuji Equia and 3 months for Fuji II LC.