Glass infiltrated multilayer zirconia: optical, mechanical and hydrothermic stability characterization

• Grant number: 23/08712-1
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2023
• Status: Discontinued
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Estevam Augusto Bonfante
• Grantee: Raphaelle Santos Monteiro de Sousa
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Associated research grant: 21/06730-7 - Towards sustainable zirconia recycled from milling waste and boosted by glass infiltration for restorative use, and of the development of strong, graded, and aging resistant multilayered zirconia blocks, AP.JP2
• Associated scholarship(s): 24/13770-3 - EFFECT OF HYDROTHERMAL AGING ON THE LIFETIME OF MULTILAYER ZIRCONIA, BE.EP.DR

Abstract

Multilayer zirconia with yttria functional gradient has been introduced in dentistry in order to combine the excellent mechanical properties of 3Y-TZP with the improved optical properties of new generations of dental zirconia (4Y- and 5Y-TZP). However, further analysis is needed regarding its behavior and characterization after interaction with the oral environment. The present proposal linked to the Young Researcher Aid-2 (JP2) #2021/06730-7 proposes the synthesis of multilayer zirconia (3Y-TZP+4Y-PSZ+5Y-PSZ) and the enhancement of its optical and mechanical properties through the process glass infiltration. The formation of a glass gradient structure has been shown to be effective in optimizing the mechanical properties of polycrystalline composites (FAPESP #19/08693-1) and second generation zirconia (FAPESP #21/07440-2), encouraging their application in zirconia multilayer. For this purpose, multilayer specimens will be processed by successive uniaxial pressing in the form of disks, which will be distributed in two groups: graduated (glass-infiltrated) and non-graded (not glass-infiltrated). After sintering and polishing, half of the specimens in each group will undergo accelerated aging at 134°C for 20 h at 2.2 bar in a hydrothermal reactor. All specimens will be characterized for analysis of microstructure and crystalline content by scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS) and X-ray diffraction (XRD) with Raman spectroscopy. The optical properties will be evaluated using reflectance tests to determine the translucency parameter and contrast ratio. The mechanical properties will be evaluated by biaxial flexural strength test with fractographic evaluation, Vickers hardness test and fracture toughness. The data obtained from optical and mechanical evaluations will be submitted to statistical analysis of variance and Tukey's test, as well as Weibull statistical analysis to evaluate characteristic strength and Weibull modulus. Additionally, material survival analysis in missions to relevant loads according to ISO:6872 will be calculated. (AU)