Effect of Two Heat Sources on the Surface Microhardness of Glass Ionomer Cement

The aim of this study was to evaluate the effect of two heat sources on the surface microhardness of a glass ionomer cement. An in vitro experimental design was used, in which 60 specimens of glass ionomer cement (GC Equia Forte) were allocated into three groups: no heat application (n = 20), heating in tempered water (n = 20), and heating with a light-emitting diode (LED) lamp (n = 20). All samples were stored in distilled water at 37 °C, and Vickers microhardness was measured after 24 hours. The results showed a significant increase in microhardness following heat application with the LED lamp compared with both the con- trol group (p = 0.000) and the tempered-water group (p = 0.000). In contrast, no statistically significant difference was found between the tempered-water group and the control group (p = 0.915). It was concluded that heat application using an LED lamp significantly enhanced the microhardness of the glass ionomer cement, whereas preheating in tempered water did not produce any changes in the material.

KEY WORDS: Glass ionomer cement, microhardness, radiant heat, temperature.