Study of colored on the microwave sintering behavior of dental zirconia ceramics

The aim of this work is to study the physical, chemical, and mechanical properties of 3 mol% Yttria-stabilized Tetragonal Zirconia Polycrystalline (3Y-TZP) materials doped with varying amounts of iron oxide (0, 400, 800, and 1000 ppm). We carried out full dense consolidation using two different sintering methods: fast-microwave technology at 1200°C and 1300°C, and conventional furnace at 1400°C. It was observed an improvement in density and hardness values, as well as great fracture toughness, and more intense color was achieved resulting in more natural color, similar to that of human teeth, using the microwave technique at 1300°C compared to the conventional method. However, the microwave-sintered specimens exhibited an increase in zirconia grains size and high color intensity along with iron oxide content when compared to conventional process, where the grain size does not vary with the coloring agent content. The results obtained in this work suggest that microwave technology can produce an increase in sintering activity due to the different dielectric properties of 3Y-TZP materials doped with Fe2O3. Another interesting confirmed result is that the addition of Fe2O3 presents a high resistance to low temperature hydrothermal degradation producing a delay in the aging process.