Surface and mechanical properties of recycled zirconia boosted by glass infiltration submitted to different etching protocols and its influence on the bond strength to Ti-6Al-4V using luting agents containing antimicrobial multi-acrylamide monomers

• Grant number: 23/13318-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: April 15, 2024
• End date: April 14, 2025
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Estevam Augusto Bonfante
• Grantee: Henrico Badaoui Strazzi Sahyon
• Supervisor: Carmem Silvia Costa Pfeifer
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Institution abroad: Oregon Health & Science University, United States
• Associated to the scholarship: 22/12118-5 - Development of the recycling process of 3Y-TZP and application in the production of composites with elastic module gradients, BP.PD

Abstract

The CAD/CAM subtractive process generates up to 80% waste of the original puck during the milling step, in the form of powder or non-milled remains. The Young Investigator Award FAPESP Phase 2 #2021/06730-7 aims to develop a methodology to successfully recycle zirconia (3Y-TZP), in line with the circular economy concept. One additional difficulty with conventional zirconia is that its high crystalline content hampers adhesion with existing cements. There is mounting evidence that glass infiltration might help overcome this issue. Finally, the success of restorations also depends on the stability of the luting material being used, with antimicrobial formulations showing promise in increasing longevity of bonded crowns. Therefore, the aim of this in vitro study is to evaluate the effect of different etching protocols on the surface and mechanical properties of recycled 3Y-TZP boosted by glass infiltration and its bond strength to a titanium alloy (Ti-6Al-4V) using luting agents containing antimicrobial multi-acrylamide monomers. Three hundred and six discs of recycled 3Y-TZP will be fabricated by uniaxial pressing and will be sorted into 3 experimental groups according to the etching protocols (tribochemical silica-coating of the zirconia; zirconia + glass infiltration + tribochemical silica-coating; and zirconia + glass infiltration + hydrofluoric acid 40% - 6 min). Ceramic surface characterization will be performed through X-ray diffraction (XRD; n=2), roughness surface (Ra and Rz) by confocal optical microscopy (n=6), scanning electron microscopy (SEM; n=2), and atomic force microscopy (AFM; n=2). Mechanical properties will be assessed by biaxial flexural strength test (ISO 6872-2015; n=30), and fractographic analysis made by SEM. Firstly, shear bond strength to Ti-6Al-4V and scanning electron micrographs will be performed using resin cement without antimicrobial activity and no aging for the three etching protocol groups (n=30). Subsequently, the experimental group that exhibits superior surface characteristics, mechanical properties, and initial shear bond strength will be submitted to a mechanical and bacteriological aging. Additionally, this experimental group will be evaluated before and after aging using resin cement containing antimicrobial properties (n=30). The data will be subjected to statistical normality tests and specific tests to verify the significance between means (± =0.05). (AU)