Surface Microhardness and Flexural Strength of Colored Zirconia

The surface microhardness and flexural strength of colored zirconia were examined. Two groups of zirconia disks (1mm thick, 20mm in diameter) within 5 disks each were shading with the same coloring liquids IL2 (Vita Classic-scale) when another group of 5 disks measured in no color. The shading time of one group was 3s and that of the other group was prolonged to 30s. The mechanical properties were tested after sintering at 1500C. Data were evaluated using ANOVA analysis. Disks of shading 30s showed a lower strength 712  53 MPa. The value of 3s was 853  46 MPa. There were no significant difference on microhardness between the two shading time. Prolonged the shading time lowered the biaxial flexural strength of zirconia ceramic, but shading time did no effect on surface microhardness.