Caracterização microestrutural e crescimento subcrítico de trincas em cerâmicas odontológicas

• Ano de defesa: 2014
• Autor(a) principal: Ramos, Nathália de Carvalho [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Cerâmicas odontológicas; Resistencia de materiais; Materiais dentários; Dental materials
• Link de acesso: http://hdl.handle.net/11449/127635; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/01-09-2015/000843256.pdf

The aim of this study was to characterize the microstructure of four dental CAD-CAM ceramics and evaluate their susceptibility to stress corrosion. SEM and EDS were performed for microstructural characterization. For evaluation of the pattern of crystallization of the ceramics and the molecular composition, XRD and FTIR, respectively, were used. Elastic modulus, Poisson's ratio, density and fracture toughness were also measured. The specimens were subjected to biaxial flexure under 5 stress rates (0.006, 0.06, 0.6, 6 and 60 MPa/s) to determine the subcritical crack growth parameters (n and D). Twenty five specimens were further tested in mineral oil for determination of Weibull parameters. Two hundred forty ceramic discs (12 mm diameter and 1.2 mm thick) were made of four ceramics: feldspathic ceramic - FEL (Vita Mark II, Vita Zahnfabrik), ceramic-infiltrated polymer- PIC (Vita Enamic, Vita Zahnfabrik), lithium disilicate - LD (IPS e.max CAD, Ivoclar Vivadent) and zirconia-reinforced lithium silicate- LS (Vita Suprinity, Vita Zahnfabrik). PIC was characterized as a geopolymer reinforced by polymers. It presented organic and inorganic phases (n = 29.1 ± 7.7) and Weibull modulus (m) of 8.96. The FEL showed n = 36.6 ± 6.8 and m = 8.02. The LD showed a structure with needle-like disilicate grains in a glassy matrix and had the lowest value of n (8.4 ± 0.8) and m= 6.19. The ZLS showed similar rod-like grains, n = 11.2 ± 1.4 and m= 9.98. The FEL showed the lowest susceptibility to SCG corrosion, where as LD and ZLS presented the highest. The PIC presented the lowest elastic modulus and no crystals in its composition. ZLS presented tetragonal zirconia in its composition and showed the highest Weibull modulus among the materials studied