Influence of the particle and air-abrasion moment on the flexural strength and phase transformation of an Y-TZP ceramic

• Grant number: 14/05429-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2014
• End date: November 30, 2015
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Renata Garcia Fonseca
• Grantee: Cláudia Carolina Jordão
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

In order to have high longevity of the indirect restorations, a strong and stable bond at the cement/restoration interface should exist. For this, since the zirconia surface is inert, surface treatments are performed to provide micromechanical retention and chemical bond. Airborne-particle abrasion is one of the most applied methods because it is simple and functional. However, this procedure may create surface flaws on the zirconia surface, which can propagate towards the bulk of the material, resulting in a decrease of its strength. On the other hand, the configuration of the air-abrasion regarding particle size, pressure, time of application and even the moment in which it is performed varies, determining the severity of the procedure and consequently its effect on the strength of the zirconia. Such problem justifies the necessity of evaluating the influence of the particle and the air-abrasion moment on the strength and phase transformation of a Y-TZP ceramic. For the flexural strength tests (20.0 × 4.0 × 1.2 mm) (n=15) and phase transformation (n=1), zirconia specimens will be obtained and: 1) will not receive any surface treatment (control group) or will be air-abraded with: 2) 50 ¼m alumina particles; 3) 120 ¼m alumina particles; 4) 30 ¼m silica-coated alumina particles (Rocatec Soft); 5) 110 ¼m silica-coated alumina particles (Rocatec Plus) and 6) 120 ¼m alumina particles followed by Rocatec Plus in one of the three air-abrasion moments: 1) after zirconia sintering (AS control group); 2) before zirconia sintering (BS) and 3) before and after zirconia sintering (BAS). Specimens will be thermocycled (10,000 cycles 5°C and 55°C for 30s). The phase transformation will be assessed by X-ray diffraction (XRD). The flexural strength test will be performed in a mechanical testing machine (EMIC DL 2000) and the data (MPa) will be statistically analyzed according to normality and homogeneity of variance tests (±=.05), considering particle and air-abrasion moment as independent variables. (AU)