Impact of deglazing on biaxial flexural strength of high translucent zirconia: effect of hydrothermal aging, pH-cycling, and load-cycling

Abstract

Background: To compare the effect of deglazing and aging on biaxial flexural strength (FS) of high translucent (HT) zirconia. Methods: 40 disc-shaped specimens (12 × 1.2 mm) of HT zirconia (3Y-PSZ, Upcera HT) were sintered after milling, glazed(G) and randomly assigned equally into 4 experimental groups: G) glazing; G-A) glazing, aging; DG-A) deglazing, aging; and NG-A) non-glazing, aging. A sequence of three methods was used for aging; hydrothermal, pH-cycling, and load cycling. FS(flexural strength) of all specimens was measured and one specimen from each group underwent X-ray diffraction (XRD) for assessment of phase transformation (t-m). Distribution of data was evaluated using the Kolmogorov -Smirnov test, and with respect to the confidence interval of 95%, data were analyzed using 1-way ANOVA with statistical software (IBM SPSS Statisticsv20.0) to compare the mean flexural strength values among the 4 groups. When significant differences were found, the mean values were compared using Tukey’s honest significant difference (HSD) test (α = 0.05). Results: FS of glazed specimens (1092.78 ± 175.40 MPaa) did not decrease after aging (1141.11 ± 117.43 MPa, P = 0.872a). FS of DG-A (1338.22 ± 175.13 MPab) and NG-A (1320.44 ± 77.44 MPab) groups was significantly higher than that of G and GA groups (P < 0.005). XRD revealed monoclinic phase in DG-A (4.23%) and NG-A (7.63%) groups. Conclusion: Loss of glaze layer and no glazing had no significant effect on FS of high translucent Y-PSZ after aging.