Glass Transition Temperatures of Dental Porcelains Determined by DSC Measurement

The differential scanning calorimetry (DSC) curves for three commercial dentin and incisal porcelains fused-to metal were measured using high-temperature DSC. The glass transition temperatures (Tg) were determined from the DSC curves at heating rates of 7-20°C/min, and the activation energy was derived from an Arrhenius plot of negative reciprocal Tg vs. logarithm of heating rate. The Tg of the dental porcelains depended on the content of aluminum oxide, whereas the activation energy depended on the content of sodium oxide. The ultra-low fusing type porcelains had a low activation energy due to the higher content of sodium oxide than the other porcelains.