Addition of Yattria Partially Stabilized Zirconia for Reinforcement of Dental Porcelain

Effect of addition of Yttria partially stabilized Zirconia powder to dental porcelain was studied. The zirconium powder was incorporated in 3, 5 and 7-percent by weight to dental porcelain powder. The measured properties were flexural strength, modulus of elasticity, fracture toughness and hardness. Samples were prepared according to the manufacturers instructions. Zirconia powder was thoroughly mixed with the porcelain powder in the correct weight percent before use. Flexural strength, modulus of elasticity, and fracture toughness were measured using three-point bending test. The hardness was measured using a conventional microhardness tester. All data were collected and analyzed with one-way analysis of variance (ANOVA) and LSD test (p=0.05). The results indicated that the addition of 3 % and 5 % Yttria partially stabilized Zirconia to the conventional dental porcelain powder resulted in increased flexural strength and fracture toughness of the porcelain. On the contrary, 3 % and 5 % zirconia decreased both the modulus of elasticity and hardness. In addition, 7 % zirconium powder decreased the studied properties. X-ray examination showed that zirconia addition increased the radiopacity of the material. It was concluded that zirconia-modified dental porcelain was stronger and tougher than the conventional unmodified ceramic.