Fatigue and pH effects on the subcritical crack growth of a dental ceramic in wet medium

• Grant number: 11/23544-0
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): February 01, 2012
• Effective date (End): December 31, 2012
• Field of knowledge: Health Sciences - Dentistry
• Principal researcher: Antonio Olavo Cardoso Jorge
• Grantee: Nathália de Carvalho Ramos Ribeiro
• Home Institution: Faculdade de Odontologia (FOSJC). Universidade Estadual Paulista (UNESP). Campus de São José dos Campos. São José dos Campos , SP, Brazil

Abstract

The aim of the present work will be to evaluate the crack growth and strength of a dental ceramic. The effects of the wet medium and of the pH variation, associated to static and dynamic fatigue will be tested with biaxial flexural strength test. One hundred ceramic disks (15 mm diameter and 1,2 mm thick) will be made of a veneering ceramic (Vita VM7, Vita Zahnfabrik, Bad Sackingen, Alemanha). Ten specimens will be indented in a Vickers durometer and tested. Ten specimens will be polished and indented .The remaining disks will be indented and subjected to storage in distilled water (37° C) or for 28 d, under a static load of 9.8 N. These specimens will be subjected to the biaxial flexural strength test under 4 loading conditions (0.1; 1; 10 e 100 MPa/s), so that the subcritical crack growth parameters can be determined. The log-log correlation correlação log-log of the flexural strength and of the loading condition will be used to calculate the parameters. The data (MPa) will be statistically analysed. The analysis of the resistance data (MPa) will be carried out, initially, by means of an exploratory approach. Next, an inferential analysis. The most appropriate statistical test will follow a parametric approach (Anova 2-factors) if the residual values of the model provide an adequate fit, following a normal probability distribution. The level of significance adopted will be the conventional value of 5%. SEM analysis will be done to evaluate the fracture characteristics.