Effect of re-sintering and grinding methods on the flexural fatigue limit of zirconia Y-TZP: analysis of the phase transformation by X-ray diffraction

• Grant number: 11/20860-9
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2013
• End date: January 31, 2015
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: José Maurício dos Santos Nunes Reis
• Grantee: José Maurício dos Santos Nunes Reis
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Associated researchers: Renata Garcia Fonseca

Abstract

This study will evaluate the effect of re-sintering and grinding methods on the fatigue limit of a Y-TZP zirconia. Furthermore, after the different treatments proposed, the phase transformation by means of X-ray diffraction (XRD) will be performed. For this, Y-TZP bars (LavaTM, 3M-ESPE) with 25 x 5.0 x 1.50 mm and 25 x 5.0 x 1.90 mm will be sintered (n=150) for 8.0 h at 1500 ºC. The dimensions of the bars after sintering will be 20 x 4.0 x 1.20 mm and 20 x 4.0 x 1.50mm. The samples with 1.20 mm in height (Control) will be submitted to fatigue limit testing before and after re-sintering procedures (1000 °C, 30 min). The samples with 1.50 mm in height will be submitted to simulated grinding. For this, the bars will be placed in a stainless steel mould for the standardization of the grinding of 0.30 mm in height. The grinding will be made by diamond burs or specific diamond-impregnated silicone points for zirconia in the presence or absence of irrigation. Half of the samples will be subject to re-sintering. For each experimental group, 15 specimens will be evaluated following the staircase method, being the initial load established at 60% of the ultimate load obtained in monotonic bending tests. The specimens will be mounted in four-point flexural devices inside artificial saliva at 37 °C, and subjected to 500,000 cycles with a frequency of 10 Hz in a mechanical testing machine MTS 810. Data analysis will be performed following the design proposed by Dixon and Mood. To verify the changes in phase of Y-TZP subjected to grinding and re-sintering, all specimens will be analyzed by XRD. In addition, three samples from each group will be subjected to scanning electron microscopy (20 and 100X) in order to verify the mode and origin of fracture and the topographic changes induced by the treatments. The results will be submitted to normality test and the most appropriate statistical method will be selected to evaluate the influence of the variation factors. (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)

POLLI, GABRIELA SCATIMBURGO; HATANAKA, GABRIEL RODRIGUES; ABI-RACHED, FILIPE DE OLIVEIRA; GOES, MARCIO DE SOUSA; DOS SANTOS NUNES REIS, JOSE MAURICIO. Fatigue behavior and surface characterization of a Y-TZP after laboratory grinding and regeneration firing. JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, v. 88, p. 305-312, DEC 2018. (11/20860-9)