Quantitative phase analysis from X-ray diffraction in Y-TZP dental ceramics: A critical evaluation

Autor(es)

Arata, A. ^{[1, 2]} ; Campos, T. M. B. ^[3] ; Machado, J. P. B. ^[4] ; Lazar, D. R. R. ^[1] ; Ussui, V. ^[1] ; Lima, N. B. ^[1] ; Tango, R. N. ^[2]

Afiliação do(s) autor(es)

^[1] Natl Nucl Energy Commiss IPEN CNEN SP, Nucl & Energy Res Inst, Mat Sci & Technol Ctr CCTM, BR-05508000 Sao Paulo - Brazil

^[2] Univ Estadual Paulista, Inst Sci & Technol, Sao Paulo - Brazil

^[3] Inst Tecnol Aeronaut, Sao Paulo - Brazil

^[4] Natl Inst Space Res INPE, Associated Lab Sensors & Mat, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Dentistry; v. 42, n. 11, p. 1487-1494, NOV 2014.
• Citações Web of Science: 10

Resumo

The dentistry literature shows consensus to use the Garvie and Nicholson equation modified by Toraya to quantify the Y-TZP phase transformation. However, this method does not include the possibility of cubic phase transformation and crystallographic texture after artificial ageing, and in this case, it is possible to observe errors of quantification. Objectives: The aim of this study was to evaluate a dental Y-TZP ageing kinetic of phase transformation under pressure and hydrothermal conditions (130 degrees C, 2 bar) and to compare the methods of quantification by the equation of Garvie and Nicholson modified by Toraya and the Rietveld refinement method. Methods: Discs of Y-TZP (12 mm empty set x 1.2 mm in height) were divided into groups (n = 4) according to the ageing times (in the range of 6 and 138 h). The superficial characterisation was made using SEM and the XDR for crystallographic analysis. Results: An aggressive superficial degradation process at the beginning of phase transformation in 6-10 h of ageing was observed by SEM. The phase transformation quantification showed differences between the methods. It was observed the increase and stabilisation of monoclinic phase until 80% at 40 h of ageing by the Garvie and Nicholson modified by Toraya equation, compared to 60% of monoclinic phase and approximately 30% of cubic phase observed by the Rietveld method. Conclusion: The Toraya equation showed an overestimated result of monoclinic quantification compared to the Rietveld method. Clinical significance: The overestimated result of monoclinic phase could lead to different interpretation about the dental Y-TZP ageing process. (C) 2014 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 10/13951-5 - Efeito do envelhecimento in vitro e in situ na transformação de fase cristalina da região de transmucoso de pilar de conexão cone morse de zircônia estabilizada por ítria (Y-TZP
• Beneficiário: Anelyse Arata
• Modalidade de apoio: Bolsas no Brasil - Mestrado