Fatigue resistance of polycrystalline composites ATZ infiltrated by glass

• Grant number: 22/02470-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2022
• End date: December 31, 2022
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Estevam Augusto Bonfante
• Grantee: Fernanda Zanelatto de Castro Paiva
• 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

Abstract

Despite the excellent mechanical properties reported for 3Y-TZP, this material is susceptible to low-temperature degradation (DBT), which motivated the development of ceramic composites associating ZrO2 and Al2O3 in different proportions (ZTA and ATZ). Data from the present group report the development of polycrystalline ceramic composites with high flexural strength (780-1,000 MPa) and resistance to DBT. Hence, an approach with glass infiltration was proposed in order to provide a gradual transition in the properties of the systems, which allowed a more favorable stress distribution and, consequently, an increase in the flexural strength (300 MPa for the graded ATZ - FAPESP report #2019/08693-1). However, the performance of glass infiltrated polycrystalline composites when subjected to cyclic load and humidity still needs to be addressed. Therefore, this project (already evaluated positively under #2021/11797-3, having been denied due to the supervisor having had BEPE# 2021/08018-2 approved and at the moment we present the advances developed voluntarily by the student, as an exchange of guidance) aims to evaluate the biomechanical behavior of the glass infiltrated ATZ when subjected to fatigue before and after hydrothermal aging. Glass-infiltrated experimental ATZ discs will be fabricated according to a previously established methodology (FAPESP #2019/08693-1 and #2020/12874-9) (n=42). Half of the specimens will be subjected to hydrothermal aging (134°C, 2.2 bar, 20 hours). Pilot dices from the result of the candidate's voluntary activity in our laboratory will be presented at the end of the project, where the microstructure and crystalline content are being characterized by SEM and XRD, and Raman, respectively. The discs will be subjected to step stress accelerated-life fatigue testing in moisture until failure or suspension. The failure distribution will be used to determine the Weibull probability curves and the probability of survival. The failure mode will be determined using a stereomicroscope.(AU)