Effect of protective surface coating on hardness, fluoride releasing and recharging ability of recent uncoated high viscosity glass ionomer cement

This study aimed to compare the Vickers hardness and amount of released and recharged fluoride ion of glass ionomer cements between various surface coating procedures at different time-points. The 270 cylindrical samples (6x2 mm) were preparedand randomly divided into three types of GICs: KetacTM Universal AplicapTM, KetacTM MolarAplicapTM and KetacTM Fil Plus AplicapTM. Each GIC was equally divided into three coating procedures (n=15/group): uncoated, coated with KetacTM Glaze and coated with G-Coat Plus. The average of the Vickers hardness was measured at 24 hours, 7 days and 30 days after incubation of specimens at 37°C in deionized water. The measurement of fluoride release and recharge were measured at 24 hours, 1, 2, 3 and 4 weeks using 1.23%APF gelas a recharging agent. A two-way ANOVA followed by post-hoc Tamhane multiple comparison test and a one-way repeated measures ANOVA were performed (p=0.05). The Vickers hardness was statistically significantly increased in both KetacTM Glaze coated and G-Coat Plus coated groups compared to uncoated group at all time-points (p<0.001). GCoat Plus coating significantly increased hardness more than KetacTM Glaze coating in KetacTM Universal AplicapTM at 30 days (p<0.001). Conversely, the coating significantlydecreased fluoride release and recharge (p<0.001), particularly in G-Coat Plus coating. In conclusion, the application of coating agents especially nanofilled resin coating improves the surface hardness, however, decreased fluoride releasing and recharging capacity of KetacTM Universal AplicapTM.