Influence of low temperature degradation on the wear resistance of recycled translucent zirconia

• Grant number: 23/07289-8
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Effective date (Start): January 18, 2024
• Effective date (End): January 17, 2025
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Estevam Augusto Bonfante
• Grantee: Larissa Marcia Martins Alves
• Supervisor: Yu Zhang
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Research place: University of Pennsylvania, United States
• Associated to the scholarship: 21/07440-2 - Graduated glass infiltration in an ultra-translucent zirconia (5Y-PSZ): synthesis, processing and characterization of physical and mechanical properties, BP.PD

Abstract

The CAD/CAM subtractive process generates 80% waste of the puck original bulk during an indirect restoration milling, where 30% becomes powder and up to 50% non-milled parts. In line with the circular economy (CE) concept, which stimulates a sustainable approach by promoting the use of recycled materials as a substitute for primary resources, the Young Investigator Grant FAPESP Phase 2 #2021/06730-7, under responsibility of the supervisor of this proposal, proposed a methodology to recycle translucent zirconia. However, the wear resistance of such material even hydrothermally aged to simulate low temperature degradation has not yet been studied. Thus, the current BEPE proposal aims to assess the wear resistance of recycled 3Y-TZP, associated with hydrothermal aging, and compare them with commercial materials. For that, in-house recycled translucent zirconia powder (3Y) will be obtained. Twenty four discs-shaped specimens (Ø= 12 mm and 1.2 mm thick) of the material will be obtained through uniaxial pressing. As control, discs of commercial materials 3Y and 5Y (Ceramill Zi and Ceramill Zolid FX, Amanngirrbach GmbH, respectively) will be also obtained. Half of the specimens from each group will be submitted to the hydrothermal aging protocol in a hydrothermal reactor at 134ºC during 20h at 2.2 bar at 3 different times to evaluate the impact of wear associated with artificial hydrothermal aging performed at 3 times during the test (1: Baseline; 2: at 400k cycles, 3: at 800k cycles). Then, all specimens will be submitted to sliding wear test against a spherical zirconia antagonist (r = 3.15 mm), with 100 N load at 1.5 Hz for 1.200,000 cycles in water. The following analyses would be performed at baseline and at each 400k cycles interval: 1) 3D laser scanner for quantitative wear analyses; 2) Crystalline content and microstructure will be evaluated using X-ray diffraction (XRD); and 3) scanning electron microscopy (SEM), respectively. Optical properties will be analyzed before and after wear test. Volume loss, wear depth data and optical properties data will be analyzed by appropriated statistical test. (AU)