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Development of pre-sintered ZTA 80% Al2O3/20% ZrO2 composite blocks for milling in CAD/CAM system

Grant number: 19/14798-0
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): October 01, 2019
Effective date (End): April 30, 2023
Field of knowledge:Health Sciences - Dentistry
Principal Investigator:Estevam Augusto Bonfante
Grantee:Adolfo Coelho de Oliveira Lopes
Home Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
Associated research grant:12/19078-7 - Development and processing of Al2O3-ZrO2 translucent composite for CAD/CAM monolithic prostheses: the effect of aging on biaxial flexural strength, AP.JP

Abstract

Yttria-stabilized Tetragonal Zirconia Polycrystal (Y-TZP) is widely used in prosthodontics but shows hydrothermal instability at low temperatures due to the transformation from the metastable tetragonal phase to the monoclinic phase, which can lead to Low-Temperature Degradation (LTD), compromising the longevity of rehabilitation treatments.The present project aims to innovate with the synthesis of polycrystalline composites in the form of pre-sintered blocks of zirconia-reinforced alumina (ZTA - Zirconia-Toughened Alumina) for CAD/CAM systems used in dentistry. Such composites highlight the best characteristics of both alumina and zirconia, offering materials with improved mechanical resistance in relation to alumina and resistant to LTD. The motivation for the development of blocks arises from the data found by the candidate during his masters supported by FAPESP 2016/17793-1 BEPE - 2017/19362-0 where ZTA composite formulated at proportion 80% Al2O3 - 20% ZrO2 presented not only resistance to LTD, but also maintenance of mechanical and optical properties after aging. Thus, the present study seeks to innovate in the next step that is to develop a method to produce pre-sintered blocks of the same ZTA composite to be milled in a CAD/CAM system. The 80% Al2O3 - 20% ZrO2 ZTA will be synthesized in custom made matrices to generate CAD/CAM blocks able to be milled. The experiment is divided into two stages: 1.1) milling of 14 mm x 1mm discs (ISO 6872: 2015) to be characterized by Energy Dispersive X-ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), density and optical properties; 1.2) Milling of discs for mechanical evaluation including biaxial flexural strength, Vickers indentation, fracture toughness and fractographic analysis. (AU)