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Silica deposition on zirconia via room-temperature atomic layer deposition (RT-ALD): effect on bond strength to veneering ceramic

Grant number: 18/24984-3
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): June 01, 2019
Effective date (End): April 30, 2020
Field of knowledge:Health Sciences - Dentistry
Principal Investigator:Aldiéris Alves Pesqueira
Grantee:Sandro Basso Bitencourt
Supervisor abroad: Benjamin Hatton
Home Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil
Local de pesquisa : University of Toronto (U of T), Canada  
Associated to the scholarship:17/13933-6 - Mechanical potential of the association of different treatments with plasma enchanced chemical deposition on zirconia surface, BP.DR

Abstract

Yttria-stabilized zirconia polycrystal (Y-TZP) can be used as an infrastructure of veneered restorations. However, the interface between Y-TZP and veneering ceramic is one of the weakest and most critical aspects of the prosthesis. In this way, surface treatments are applied to improve the bond strength between Y-TZP and veering layer. Y-TZP is susceptible to low temperature degradation (LTD), a spontaneous t-m transformation that occurs over time at low temperatures. This aging process can be accelerated using an autoclave and controlled protocols and the transformed surface layer presents roughening and microcracks. The nano-vacancies of the porous t-m transformed layer have potential to be infiltrated by films developed through a technique called atomic layer deposition (ALD). ALD can effectively deposit silica (SiO2) on the desired surfaces. A new way to perform the ALD treatment it based on the room-temperature of the ALD (RT-ALD), a simple method for thin films deposition that can create a silica layer using inexpensive benchtop lab equipment and in ambient conditions. Thus, the overall goal of this study is to develop a hybrid interface between Y-TZP porous t-m transformed layer and silica-based nanofilm using RT-ALD. The aging protocol will be optimized to obtain a porous surface without significant decrease in the mechanical properties. The RT-ALD will then be employed to generate a uniform silica film on the surface of Y-TZP. Mechanical properties of the aged samples, the quality of the silica film deposition and the bond strength between the experimental surfaces and veneering material will be assessed (Fringe Projection Phase Shifting, Scanning Electronic Microscopy and Energy-dispersive Spectroscopy, Atomic force microscopy, Surface profilometry and Surface-free energy). The bond strength will be assessed after application of a veneering ceramic and the mode of failure will be evaluated. The data obtained will be submitted to the normal curve adherence test, with the appropriate statistic test being applied for the comparison of mean values of the samples (±=0.05).

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