کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1420477 | 1508929 | 2014 | 11 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Effect of in vitro aging on the flexural strength and probability to fracture of Y-TZP zirconia ceramics for all-ceramic restorations Effect of in vitro aging on the flexural strength and probability to fracture of Y-TZP zirconia ceramics for all-ceramic restorations](/preview/png/1420477.png)
ObjectivesDental zirconia restorations should present long-term clinical survival and be in service within the oral environment for many years. However, low temperature degradation could affect their mechanical properties and survival. The aim of this study was to investigate the effect of in vitro aging on the flexural strength of yttrium-stabilized (Y-TZP) zirconia ceramics for ceramic restorations.MethodsOne hundred twenty bar-shaped specimens were prepared from two ceramics (ZENO Zr (WI) and IPS e.max® ZirCAD (IV)), and loaded until fracture according to ISO 6872. The specimens from each ceramic (nx = 60) were divided in three groups (control, aged for 5 h, aged for 10 h). One-way ANOVA was used to assess statistically significant differences among flexural strength values (P < 0.05). The variability of the flexural strength values was analyzed using the two-parameter Weibull distribution function, which was applied for the estimation of Weibull modulus (m) and characteristic strength (σ0). The crystalline phase polymorphs of the materials (tetragonal, t, and monoclinic, m, zirconia) were investigated by X-ray diffraction (XRD) analysis, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy.ResultsA slight increase of the flexural strength after 5 h, and a decrease after 10 h of aging, was recorded for both ceramics, however statistically significant was for the WI group (P < 0.05). Both ceramics presented a t → m phase transformation, with the m-phase increasing from 4 to 5% at 5 h to around 15% after 10 h.SignificanceThe significant reduction of the flexural strength after 10 h of in vitro aging, suggests high fracture probability for one of the zirconia ceramics tested.
Journal: Dental Materials - Volume 30, Issue 12, December 2014, Pages e306–e316