Preparation and characterization of new dental porcelains, using K-feldspar and quartz raw materials. Effect of B2O3 additions on sintering and mechanical properties

The aim of this work was to determine the effect of temperature and boric oxide (B2O3) addition on sintering and mechanical properties of a newly developed dental porcelain (DP) prepared from local Algerian raw materials. Based on a preliminary work, the new selected composition was 75 wt.% feldspar, 20 wt.% quartz and 5 wt.% kaolin. It was prepared by sintering the mixture at different temperatures (1100-1250 °C). The optimum sintering conditions gave a relatively higher density (2.47 g/cm3) and excellent mechanical properties. The three point flexural strength (3PFS) and Martens micro-hardness of dental porcelains were 149 MPa and 2600 MPa, respectively. This obtained 3PFS value is more than four times greater than that of hydroxyapatite (HA) value (about 37 MPa) sintered under the same conditions. However, the sintering temperature was lowered by about 25 and 50 °C for 3 and 5 wt.% B2O3 additions, respectively. But, it did not improve furthermore the samples density and their mechanical properties. It has also been found that B2O3 additions provoke a glass matrix composition variation which delays the leucite formation during sintering.