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Effects of mechanical and hydrothermal aging on microstructure, optical and mechanical properties of high translucency monolithic free-veneering zirconia

Grant number: 13/22539-9
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): September 01, 2014
Effective date (End): September 30, 2016
Field of knowledge:Health Sciences - Dentistry - Dental Materials
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal researcher:Gelson Luis Adabo
Grantee:Eduardo Mariscal Muñoz
Home Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Yttrium stabilized zirconium (Y-TZP) is indicated for metal free dental prosthesis and has better mechanical properties than any other dental ceramics. However, usually it needs to be veneered by feldspathic porcelain in order to obtain aesthetic results due to Y-TZP high opacity. Nevertheless, veneer ceramic represents the weakest part of this kind of prostheses since clinical chipping of porcelain veneering is quite common. Recently, high translucency monolithic Y-TZP has been introduced aiming to eliminate porcelain veneering. Nevertheless, since Y-TZP is known to be susceptible to hydrothermal degradation and/or accelerated aging that leads to premature fails when allocated in moist ambient, it is very important to explore possible significances of these processes in materials in oral environment. The aim of this study is to analyze aging induced in monolithic Y-TZP and possible consequences on microstructure, flexural strength, fatigue, optical properties and wear. Cylindrical specimens (15 mm of diameter and 1.2 mm of thickness) in two high translucency monolithic Y-TZP (Lava Plus High Translucency - 3M e Prettau Zirconia - Zirkhonzan) and two Y-TZP for frame (Lava Frame - 3M e Ice Zirkon Transluzent - Zirkhonzan) will be subject to 3 different degradation processes: mechanical cycling, hydro-thermal degradation and the association between both processes. The microstructure and superficial morphology analysis will be carried out by SEM (scanning electron microscopy), roughness (Ra) and grain size will be measured using AFM (atomic force microscopy) as well as crystalline phase composition using X-ray diffraction technique. Transmittance and reflectance optical properties analyses will be performed in 360 - 740 nm wave length and it will be obtained since mean transmittance, mean reflectance, opacity (%), translucency, opalescence and light dispersion summary values. Mechanical properties will be assessed by bi-axial resistance, fatigue limit and wear resistance assays. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MUNOZ, EDUARDO MARISCAL; LONGHINI, DIOGO; ANTONIO, SELMA GUTIERRES; ADABO, GELSON LUIS. The effects of mechanical and hydrothermal aging on microstructure and biaxial flexural strength of an anterior and a posterior monolithic zirconia. Journal of Dentistry, v. 63, p. 94-102, AUG 2017. Web of Science Citations: 15.
Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
MUÑOZ, Eduardo Mariscal. Efeito do envelhecimento mecânico e degradação hidrotérmica sobre a microestrutura, propriedades ópticas e mecânicas da zircônia monolítica indicada para próteses sem cobertura de porcelana. 2017. 76 f. Doctoral Thesis - Universidade Estadual Paulista "Júlio de Mesquita Filho" Faculdade de Odontologia (Campus de Araraquara)..

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