کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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791 | 63 | 2012 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Low-temperature degradation of different zirconia ceramics for dental applications Low-temperature degradation of different zirconia ceramics for dental applications](/preview/png/791.png)
The aim of this investigation was to determine the influence of simulated ageing on the tetragonal-to-monoclinic phase transformation and on the flexural strength of a 3Y-TZP ceramic, compared to alumina toughened zirconia (ATZ) and ceria-stabilized zirconia (12Ce-TZP). Standardized disc specimens of each material were hydrothermally aged in steam at 134 °C and 3 bar for 0, 16, 32, 64 or 128 h. The phase transformation was determined by X-ray diffraction (XRD) and atomic force microscopy. Scanning electron microscopy was performed to estimate the depth of the transformation zone. The flexural strength was investigated in a biaxial flexural test. XRD revealed a significant increase in the monoclinic phase content for 3Y-TZP and ATZ due to ageing, although this increase was less pronounced for ATZ. In contrast, the monoclinic phase content of 12Ce-TZP was not influenced. For 3Y-TZP and ATZ, a transformation zone was found of which the depth linearly correlated with ageing time, while for 12Ce-TZP no transformation zone could be observed. Changes in flexural strength after ageing were heterogeneous: while 3Y-TZP showed a significant decrease in strength – from 1740 to 1169 MPa – with ATZ there was a considerable increase – from 1093 to 1378 MPa. The flexural strength of 12Ce-TZP remained unaffected at the low level of about 500 MPa. These results indicate that both alumina and ceria, as stabilizing oxides, reduce the susceptibility of zirconia to hydrothermal degradation; the alternative use of these oxides may enhance the clinical long-term stability of dental zirconia restorations.
Journal: Acta Biomaterialia - Volume 8, Issue 3, March 2012, Pages 1213–1220