Microstructure characterization and SCG of newly engineered dental ceramics

Author(s)

Ramosa, Nathalia de Carvalho ^[1] ; Bastos Campos, Tiago Moreira ^[2] ; de la Paza, Igor Siqueira ^[1] ; Barros Machado, Joao Paulo ^[3] ; Bottino, Marco Antonio ^[1] ; Cesar, Paulo Francisco ^[4] ; de Melo, Renata Marques ^[1]

Affiliation

^[1] Sao Paulo State Univ UNESP, Inst Sci & Technol, Dept Dent Mat & Prosthodont, 777 Engn Francisco Jose Longo Ave, BR-12245000 Sao Jose Dos Campos, SP - Brazil

^[2] ITA, 50 Praca Marechal Eduardo Gomes, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[3] Natl Inst Space Res, Associated Lab Sensors & Mat, 1758 Astronautas Ave, BR-12217010 Sao Jose Dos Campos, SP - Brazil

^[4] Univ Sao Paulo, Sch Dent, Dept Biomat & Oral Biol, 2227 Prof Lineu Prestes Ave, BR-05508000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Dental Materials; v. 32, n. 7, p. 870-878, JUL 2016.
• Web of Science Citations: 40

Abstract

Objectives. The aim of this study was to characterize the microstructure of four dental CAD-CAM ceramics and evaluate their susceptibility to stress corrosion. Methods. 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 five 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 from 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). Results. PIC discs presented organic and inorganic phases (n = 29.1 +/- 7.7) and Weibull modulus (m) of 8.96. The FEL discs showed n = 36.6 +/- 6.8 and m = 8.02. The LD discs 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 discs showed similar rod-like grains, n =11.2 +/- 1.4 and m = 9.98. Significance. The FEL and PIC discs showed the lowest susceptibility to slow crack growth (SCG), whereas the LD and ZLS discs presented the highest. PIC presented the lowest elastic modulus and no crystals in its composition, while ZLS presented tetragonal zirconia. The overall strength and SCG of the new materials did not benefit from the additional phase or microconstituents present in them. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/15541-7 - Microstructure characterization and subcritical crack growth of dental ceramics
• Grantee: Nathália de Carvalho Ramos Ribeiro
• Support Opportunities: Scholarships in Brazil - Master