[The effect of heat application on microhardness of glass ionomer cement and on pulp temperature]

To examine the effect of energy application on microhardness of Glass ionomer cement (GIC), and the effect of the temperature applied on pulp temperature, in vitro.

Discs of EQUIA (GC Co. Japan) were examined for microhardness using Vickers indentations after heat application of 50 or 60°C for 30 or 60 seconds using light curing devices or a specific heating device, and compared to self setting GIG. The measurements were performed after 30, 60 minutes and after 5 days. Heat was applied to GIC occlusal restorations in deciduous and permanent teeth in vitro and the effect on pulp temperature was measured using a thermo-coupling device. The best microhardness results were observed using a specific heating device at 50°C for 30 or 60 seconds, and the differences to self setting material after 60 minutes were statistically significant. After 5 days the differences in microhardness were non- significant. Temperature of 60°C caused the pulp temperature to rise with more than the accepted 5.5°C and may cause irreversible damage to the pulp. The application of heat energy to GIC using a heating device improved the surface microhardness significantly during the first 60 minutes. The temperature to be used is around 50°C for 30 seconds in order not to cause irreversible damage to the pulp.