IADR Abstract Archives
Flexural Strength of Multilayer Zirconia Depending on Sintering and Aging
Objectives: The aim was to evaluate the biaxial flexural strength of composition-gradient multilayer zirconia depending on sintering program and aging by thermocycling.
Methods: In total, 96 specimens divided into 12 groups (n=8) depending on material, layer content, sintering program, and aging were produced. Sixty-four specimens from the composition-gradient KATANA™ Zirconia YML were milled from two different positions in the disc, including the layers Enamel-Body 1 (E) and Body 2-Body 3 (B), and 32 specimens from the color-gradient KATANA™ Zirconia UTML, as external control groups (C). The specimens were designed according to ISO:6872 with a diameter of 14 mm and thickness of 1.2 mm. Half of the groups were speed sintered and half conventionally sintered. The specimens were polished in pre-sintered and fully sintered stage. Half of the groups of each sintering group were thermocycled for 10,000 cycles in distilled water between two baths with temperatures of 5±2°C and 55±5°C. The biaxial flexural strength was measured with the piston-on-three-ball method and the results analyzed with three-way ANOVA, the factors layers/material, sintering program and aging and a significance level of α = 0.05.
Results: There was a statistically significant difference between all the layers/material groups; the B groups showing significantly higher flexural strength than the E groups followed by the external control C groups. Thermocycling resulted in significantly higher flexural strength compared to no aging. There were no statistically significant interactions between the three factors.
Conclusions: The biaxial flexural strength of multilayer zirconia is more dependent on material composition, position in the disc, and aging than sintering program. Aging by thermocycling (10,000 cycles) increases the biaxial flexural strength. Conventional and speed sintering result in similar biaxial flexural strength.
Methods: In total, 96 specimens divided into 12 groups (n=8) depending on material, layer content, sintering program, and aging were produced. Sixty-four specimens from the composition-gradient KATANA™ Zirconia YML were milled from two different positions in the disc, including the layers Enamel-Body 1 (E) and Body 2-Body 3 (B), and 32 specimens from the color-gradient KATANA™ Zirconia UTML, as external control groups (C). The specimens were designed according to ISO:6872 with a diameter of 14 mm and thickness of 1.2 mm. Half of the groups were speed sintered and half conventionally sintered. The specimens were polished in pre-sintered and fully sintered stage. Half of the groups of each sintering group were thermocycled for 10,000 cycles in distilled water between two baths with temperatures of 5±2°C and 55±5°C. The biaxial flexural strength was measured with the piston-on-three-ball method and the results analyzed with three-way ANOVA, the factors layers/material, sintering program and aging and a significance level of α = 0.05.
Results: There was a statistically significant difference between all the layers/material groups; the B groups showing significantly higher flexural strength than the E groups followed by the external control C groups. Thermocycling resulted in significantly higher flexural strength compared to no aging. There were no statistically significant interactions between the three factors.
Conclusions: The biaxial flexural strength of multilayer zirconia is more dependent on material composition, position in the disc, and aging than sintering program. Aging by thermocycling (10,000 cycles) increases the biaxial flexural strength. Conventional and speed sintering result in similar biaxial flexural strength.