The Effect of Li2O and B2O3 on Thermal Properties and Chemical Solubility of Low-Fusing Dental Porcelain

Abstract

Alkali oxides were added to glass frit in order to lower the firing temperature of dental porcelain, and the effects of Li2O and B2O3 on the thermal properties and chemical solubility of low-fusing dental porcelain were investigated. The glass transition temperature(Tg) and softening temperature(Ts) of glass frits were decreased remarkably by adding Li2O, but the coefficient of thermal expansion(CTE) was increased with Li2O. In the case of adding B2O3, the thermal properties were unchanged. Tg of B0L4, B2L4 and B4L4 specimens were lower than 500°C and Ts were lower than 550°C. The chemical solubility of prepared low-fusing dental porcelain with these glass frits were 37.3, 43.9, and 49.2µg·cm-2 respectively. The chemical solubility was increased by adding Li2O and B2O3, but all the results were below 100µg·cm-2 and satisfactory to ISO Standards. Further, the chemical solubility of the commercial low-fusing dental porcelains were 52.6µg·cm-2 for Ceramco Finesse(Clear), 70.8µg·cm-2 for Duceram-LFC(TC) and that of conventional dental porcelain, CeraMax(T-C), was 34.8µg·cm-2.