title: Surface and Mechanical Characterization of Dental Yttria-Stabilized Tetragonal Zirconia Polycrystals (3Y-TZP) After Different Aging Processes.
abstract: Yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) is a ceramic material used in indirect dental restorations. However, phase transformation at body temperature may compromise the material's mechanical properties, affecting the clinical performance of the restoration. The effect of mastication on 3Y-TZP aging has not been investigated. 3Y-TZP specimens (IPS E-max ZirCAD and Z5) were aged in three different modes (n=13): no aging (control), hydrothermal aging (HA), or chewing simulation (CS). Mechanical properties and surface topography were analyzed. Analysis of variance showed that neither aging protocol (p=0.692) nor material (p=0.283) or the interaction between them (p=0.216) had a significant effect on flexural strength, values ranged from 928.8 MPa (IPSHA) to 1,080.6 MPa (Z5HA). Nanoindentation analysis showed that material, aging protocol, and the interaction between them had a significant effect (p<0.001) on surface hardness and reduced Young's modulus. The compositional analysis revealed similar yttrium content for all the experimental conditions (aging: p=0.997; material: p=0.248; interaction material×aging: p=0.720). Atomic force microscopy showed an effect of aging protocols on phase transformation, with samples submitted to CS exhibiting features compatible with maximized phase transformation, such as increased volume of the material microstructure at the surface leading to an increase in surface roughness.
authors: 1Faculty of Dentistry,University of Toronto,Edward Street #352E,Toronto,ON,Canada,M5G 1G6.
authors: Palena A
authors: PA
authors: Pinto
authors: 2Department of Mechanical and Industrial Engineering,University of Toronto,5 King's College Road #MB115,Toronto,ON,Canada,M5S 3G8.
authors: Guillaume
authors: G
authors: Colas
authors: 2Department of Mechanical and Industrial Engineering,University of Toronto,5 King's College Road #MB115,Toronto,ON,Canada,M5S 3G8.
authors: Tobin
authors: T
authors: Filleter
authors: 1Faculty of Dentistry,University of Toronto,Edward Street #352E,Toronto,ON,Canada,M5G 1G6.
authors: Grace M
authors: GM
authors: De Souza
keywords: chewing simulator; dental materials; hydrothermal aging; low-temperature degradation; zirconia