Kátia Vieira Cardoso1, Gelson Luis Adabo2, Eduardo Mariscal-Muñoz3, Selma Gutierres Antonio4, João Neudenir Arioli Filho5. 1. Doctoral student, Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil. Electronic address: katiavcardoso@hotmail.com. 2. Professor of Dental Materials, Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil. 3. Associate Professor, Department of Dental Clinics, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico. 4. Postdoctoral research associate, Department of Physical Chemistry, Araraquara Institute of Chemistry, São Paulo State University (UNESP), Araraquara, Brazil. 5. Adjunct Professor of Complete Prosthodontics, Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil.
Abstract
STATEMENT OF PROBLEM: Fully stabilized monolithic zirconia (FSZ) has been developed as an alternative to zirconia veneered with porcelain. However, how sintering conditions might affect its microstructure and optical and mechanical properties is unclear. PURPOSE: The purpose of this in vitro study was to determine the effect of different sintering temperatures on the microstructure and optical and mechanical properties of FSZ. MATERIAL AND METHODS: Bar-shaped FSZ specimens were prepared and divided into 2 groups (n=15) according to final sintering temperatures (1450 °C and 1600 °C). The average reflectance, opacity, translucency parameter, and sum of light absorption-scattering values were obtained by using a spectrophotometer, and ΔE00 was calculated. The 3-point bend test was performed in a universal testing machine. Scanning electron microscopy (SEM) was conducted for microstructure analysis. Crystalline phase quantification was obtained by X-ray diffraction (XRD). Data were analyzed by using D'Agostino-Pearson and Student t tests (α=.05). RESULTS: A significant difference was detected in the reflectance and sum of light absorption-scattering values between the 2 groups. The translucency parameter, opacity, and flexural strength showed no statistical differences. ΔE00 was 0.98. XRD indicated cubic (47.41% for 1450 °C; 46.04% for 1600 °C) and tetragonal content (52.59% for 1450 °C; 53.96% for 1600 °C). No monoclinic content was found. SEM images showed more definite grain boundaries in the 1600-°C group. Mean grain size was 0.49 μm for the 1450-°C group and 1.99 μm for the 1600-°C group. CONCLUSIONS: Higher sintering temperatures increased the grain size but did not change the crystal phase concentration. A significant difference was found in the reflectance and sum of light absorption-scattering, but no differences were found among the translucency parameter, opacity, or flexural strength.
STATEMENT OF PROBLEM: Fully stabilized monolithic zirconia (FSZ) has been developed as an alternative to zirconia veneered with porcelain. However, how sintering conditions might affect its microstructure and optical and mechanical properties is unclear. PURPOSE: The purpose of this in vitro study was to determine the effect of different sintering temperatures on the microstructure and optical and mechanical properties of FSZ. MATERIAL AND METHODS: Bar-shaped FSZ specimens were prepared and divided into 2 groups (n=15) according to final sintering temperatures (1450 °C and 1600 °C). The average reflectance, opacity, translucency parameter, and sum of light absorption-scattering values were obtained by using a spectrophotometer, and ΔE00 was calculated. The 3-point bend test was performed in a universal testing machine. Scanning electron microscopy (SEM) was conducted for microstructure analysis. Crystalline phase quantification was obtained by X-ray diffraction (XRD). Data were analyzed by using D'Agostino-Pearson and Student t tests (α=.05). RESULTS: A significant difference was detected in the reflectance and sum of light absorption-scattering values between the 2 groups. The translucency parameter, opacity, and flexural strength showed no statistical differences. ΔE00 was 0.98. XRD indicated cubic (47.41% for 1450 °C; 46.04% for 1600 °C) and tetragonal content (52.59% for 1450 °C; 53.96% for 1600 °C). No monoclinic content was found. SEM images showed more definite grain boundaries in the 1600-°C group. Mean grain size was 0.49 μm for the 1450-°C group and 1.99 μm for the 1600-°C group. CONCLUSIONS: Higher sintering temperatures increased the grain size but did not change the crystal phase concentration. A significant difference was found in the reflectance and sum of light absorption-scattering, but no differences were found among the translucency parameter, opacity, or flexural strength.