• low-temperature degradation of different zirconia ceramics for dental applications

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    جزئیات بیشتر مقاله
    • تاریخ ارائه: 1392/01/01
    • تاریخ انتشار در تی پی بین: 1392/01/01
    • تعداد بازدید: 750
    • تعداد پرسش و پاسخ ها: 0
    • شماره تماس دبیرخانه رویداد: -
     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.

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