Fatigue resistance of an ultra-translucent zirconia (5Y-PSZ) glass infiltrated

• Grant number: 23/00898-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2023
• End date: December 31, 2023
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Larissa Marcia Martins Alves
• Grantee: Ana Clara Mota de Oliveira
• 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

Glass infiltration in polycrystalline ceramics improves optical, mechanical and adhesive properties. Despite the fact that such advantages have already been proven for 1st and 2nd generation zirconia, these materials are susceptible to low temperatures degradation (LTD), which motivated the central scope of JP #2012/19078-7 for the development of composites associating zirconia and alumina. Data from the JP grant reported to FAPESP and published by our team demonstrated the successful development of composites resistant to LTD, however due their opacity, the use of these systems is restricted for infrastructure only. Therefore, glass infiltration has been proposed in order to improve the optical and mechanical properties of these systems (FAPESP #2019/08693-1, #2020/12874-9, #2021/06730-7 and #2021/07440-2) . On the other hand, 3rd generation zirconia are resistant to LTD, since its microstructure contains mostly cubic phase and does not undergo phase transformation, which, on the other hand, restricts the toughening process and drastically reduces its mechanical performance. Thus, the development of a glass for the graded infiltration of 3rd generation zirconia, aiming at improving the mechanical, aesthetic and adhesive properties was proposed by our research group and is being carried out through the granting of a postdoctoral fellowship by the supervisor of this proposal (FAPESP #2021/07440-2). Preliminary results, presented on the project, demonstrated the effectiveness of the glass infiltration technique in 5Y-PSZ through the characterization of the microstructure and crystalline content by SEM and XRD, respectively. However, it is also necessary to investigate the performance of this material when subjected to cyclic loads and humidity. Therefore, this project proposes the evaluation of a 3rd generation zirconia glass infiltrated when subjected to fatigue. 5Y-PSZ discs will be made (n=46). Half of the specimens will be glass-infiltrated following the methodology proposed in FAPESP #2021/07440-2. The discs will be subjected to progressive accelerated fatigue testing in humidity until failure or suspension. The failure distribution will be used to determine the Weibull probability curves and the survival probability. The failure mode will be determined using a stereomicroscope.