IADR Abstract Archives
Effects of Colorants on Mechanical and Physical Properties of Zirconia
Objectives: To examine the effects of colorants on mechanical and physical properties of VITA YZ zirconia.
Methods: VITA In-Ceram YZ 40/15 zirconia blocks and two colorants, VITA YZ HT Shade Liquid 2M2 and 3M2, were used. Application of colorants onto zirconia were done by two methods: immersion (2 and 4 minutes) and coating (4, 8, and 12 coats). The study had eleven groups: two colorant levels crossing five treatment levels accounted for 10 groups, and a control group absent of colorants. Each group included eight specimens, with final dimensions of 4×2×12 mm bars.
Specimens were prepared by sectioning using Buehler IsoMet 5000 saw to the dimension of 5.3×2.7×15.9 mm to compensate sintering shrinkage. Sectioned bars were dried in a convection oven for 45 minutes at 115 degree Celcius and cleaned by VITA Vacumet using Cleaning Firing cycle. Specimens were dried again before sintering, which the specimens were placed in VITA ZYrcomatT furnace for a 7.5-hour firing cycle. Specimens were tested using 3-point bending test by Instron 5566A with a 10 mm support span fixture. Load to failure were calculated into flexural strength (MPa). Data were analyzed through ANOVA, TUKEY, and Weibull Analysis using JMP Pro. Additionally, specimens’ surfaces and cross-sections were examined under scanning electron microscope (Hitachi SU6600) and stereomicroscope for analysis of color infiltration and grain-size.
Results: Mean flexural strength and Weibull modulus are shown in Table 1. SEM analysis showed notable increase of debris and irregular grain shape for colorant treated groups compared to controls.
Conclusions: Although no significant difference in flexural strength was observed between the tested groups, the large decrease in Weibull modulus from control to colored specimens suggested the colorants influenced the reliability of the zirconia material. The decreased reliability possibly resulted from alterated microstructure of zirconia by the colorants.
Methods: VITA In-Ceram YZ 40/15 zirconia blocks and two colorants, VITA YZ HT Shade Liquid 2M2 and 3M2, were used. Application of colorants onto zirconia were done by two methods: immersion (2 and 4 minutes) and coating (4, 8, and 12 coats). The study had eleven groups: two colorant levels crossing five treatment levels accounted for 10 groups, and a control group absent of colorants. Each group included eight specimens, with final dimensions of 4×2×12 mm bars.
Specimens were prepared by sectioning using Buehler IsoMet 5000 saw to the dimension of 5.3×2.7×15.9 mm to compensate sintering shrinkage. Sectioned bars were dried in a convection oven for 45 minutes at 115 degree Celcius and cleaned by VITA Vacumet using Cleaning Firing cycle. Specimens were dried again before sintering, which the specimens were placed in VITA ZYrcomatT furnace for a 7.5-hour firing cycle. Specimens were tested using 3-point bending test by Instron 5566A with a 10 mm support span fixture. Load to failure were calculated into flexural strength (MPa). Data were analyzed through ANOVA, TUKEY, and Weibull Analysis using JMP Pro. Additionally, specimens’ surfaces and cross-sections were examined under scanning electron microscope (Hitachi SU6600) and stereomicroscope for analysis of color infiltration and grain-size.
Results: Mean flexural strength and Weibull modulus are shown in Table 1. SEM analysis showed notable increase of debris and irregular grain shape for colorant treated groups compared to controls.
Conclusions: Although no significant difference in flexural strength was observed between the tested groups, the large decrease in Weibull modulus from control to colored specimens suggested the colorants influenced the reliability of the zirconia material. The decreased reliability possibly resulted from alterated microstructure of zirconia by the colorants.