Hilton Riquieri1, Jaiane Bandoli Monteiro2, Diogo Cabecinha Viegas3, Tiago Moreira Bastos Campos4, Renata Marques de Melo5, Guilherme de Siqueira Ferreira Anzaloni Saavedra6. 1. Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José dos Campos, SP, Brazil. Electronic address: hilton.riquieri@terra.com.br. 2. Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José dos Campos, SP, Brazil. Electronic address: jaiane.monteiro@ict.unesp.br. 3. Faculty of Dental Medicine, Lisbon University, 1649-003, Lisbon, Portugal. Electronic address: diogo.pviegas@gmail.com. 4. Aeronautics Technological Institute (ITA), 50 Praça Marechal Eduardo Gomes, 12228-900, São José dos Campos, São Paulo State, Brazil. Electronic address: moreiratiago22@gmail.com. 5. Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José dos Campos, SP, Brazil. Electronic address: renata.marinho@fosjc.unesp.br. 6. Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José dos Campos, SP, Brazil. Electronic address: saavedra@ict.unesp.br.
Abstract
OBJECTIVES: The aim of this study was to characterize the microstructure of two zirconia-reinforced lithium silicate (ZLS) glass-ceramics and evaluate their mechanical properties before and after the crystallization firing process (CFP). METHODS: Field emission-scanning electron microscope (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed for microstructural characterization. To evaluate the pattern of crystallization and the molecular composition of ZLS glass-ceramics, was used X-ray diffraction (XRD). Vickers hardness, fracture toughness by the indentation method, and biaxial flexural strength were also measured. One hundred and forty ceramic discs were produced (diameter=12mm; thickness=1.2mm) and allocated among four groups (n=30): Sfir, Sunf-ZLS Vita Suprinity; and Cfir and Cunf-ZLS Celtra Duo; fired and unfired, respectively. Statistical analysis was performed and Weibull failure probabilities were calculated. RESULTS: Cfir showed the highest characteristic strength (251.25MPa) and hardness (693.333±10.85GPa). Conversely, Sunf presented the lowest characteristic strength (106.95MPa) and significantly lowest hardness (597.533±33.97GPa). According to Weibull analysis, Sunf had the highest structural reliability (m=7.07), while Sfir presented the lowest (m=5.38). The CFP was necessary to crystallize zirconia in the partially crystallized ZLS glass-ceramics. Sfir had a lower percentage of crystallized zirconia than did Cfir. Fractographic analyses showed that all failures initiated from an inherent critical defect in Sunf and from processing defects in the remaining groups. SIGNIFICANCE: The CFP had a direct influence on the flexural strength and microstructural characteristics of both ZLS materials.
OBJECTIVES: The aim of this study was to characterize the microstructure of two zirconia-reinforced lithium silicate (ZLS) glass-ceramics and evaluate their mechanical properties before and after the crystallization firing process (CFP). METHODS: Field emission-scanning electron microscope (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed for microstructural characterization. To evaluate the pattern of crystallization and the molecular composition of ZLS glass-ceramics, was used X-ray diffraction (XRD). Vickers hardness, fracture toughness by the indentation method, and biaxial flexural strength were also measured. One hundred and forty ceramic discs were produced (diameter=12mm; thickness=1.2mm) and allocated among four groups (n=30): Sfir, Sunf-ZLS Vita Suprinity; and Cfir and Cunf-ZLS Celtra Duo; fired and unfired, respectively. Statistical analysis was performed and Weibull failure probabilities were calculated. RESULTS: Cfir showed the highest characteristic strength (251.25MPa) and hardness (693.333±10.85GPa). Conversely, Sunf presented the lowest characteristic strength (106.95MPa) and significantly lowest hardness (597.533±33.97GPa). According to Weibull analysis, Sunf had the highest structural reliability (m=7.07), while Sfir presented the lowest (m=5.38). The CFP was necessary to crystallize zirconia in the partially crystallized ZLS glass-ceramics. Sfir had a lower percentage of crystallized zirconia than did Cfir. Fractographic analyses showed that all failures initiated from an inherent critical defect in Sunf and from processing defects in the remaining groups. SIGNIFICANCE: The CFP had a direct influence on the flexural strength and microstructural characteristics of both ZLS materials.
Authors: Hafiz A Adawi; Mohammed M Al Mialeem; Nasser M Al Ahmari; Mansoor Shariff; Mohammed A Qahhar; Sultan M H Muharraq; Nabiel A Alghazali Journal: Med Sci Monit Date: 2021-10-03