Low temperature degradation of a Y-TZP dental ceramic.

Cattani-Lorente M; Scherrer SS; Ammann P; Jobin M; Wiskott HW

doi:10.1016/j.actbio.2010.09.020

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Journal article

Low temperature degradation of a Y-TZP dental ceramic.

Cattani-Lorente M Laboratory of Biomaterials, School of Dentistry, University of Geneva, 19 rue Barthélémy-Menn, CH 1205 Geneva, Switzerland.
Scherrer SS
Ammann P
Jobin M
Wiskott HW

2010-09-22

Published in:

Acta biomaterialia. - 2011

Microscopy, Electron, Scanning

English Bars of Y-TZP ceramic for dental restorations were subjected to hydrothermal degradation via in vitro exposure to water steam at 140°C for 7 days. X-ray diffraction, atomic force microscopy and scanning electron microscopy techniques were applied to observe and quantify the tetragonal-monoclinic (t-m) phase transformation associated with the process. Nanoindentation was used to assess the ceramic's mechanical properties before and after hydrothermal degradation. Texture associated with martensitic t-m transformation was observed at the grain surface. The t-m transformation followed nucleation-and-growth kinetics, with predominance of the nucleation process. The transformation occurred within a layer of 6 μm below the surface. Mechanical properties deteriorated with hydrothermal degradation, resulting in a 30% reduction of Young's modulus and hardness. A strong correlation was found between the increasing monoclinic fraction and the decline in mechanical response. It was thus concluded that the emergence of the monoclinic phase and the associated microcracking were the most likely causes for the degradation of mechanical properties.

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