Flexural Strength of Two Multilayered and Monochromatic High Yttria Containing Zirconia Materials Following Different Sintering Parameters

Sintering parameters influence the properties of zirconia. This study examined the effect of altering sintering temperature and time of monochrome and multilayer 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) on flexural strength. Three hundred specimens (width × length × thickness = 10 × 20 × 2 mm) were prepared from monolayer (Z ) and multilayer (Z ) 5Y-PSZ and randomly sintered at decreasing (T : 1,450°C), regular (T : 1,500°C), and increasing (T : 1,550°C) sintering temperature, with extremely short (H : 10 minutes), ultrashort (H : 15 minutes), short (H : 30 minutes), and regular (H : 135 minutes) sintering time ( = 15/group). The precrack was induced on the tension side before testing for flexural strength ( ). Analysis of variance and Tukey's test were used for significant differences of at 0.05). Sintering zirconia at T or H indicated significantly higher than sintering at T or T or with H , H , or H for both Z and Z ( 0.05). SEM indicated intergranular and transgranular fractures. XRD revealed predominately c- and t-phases and minor amounts of m-phase. Increasing sintered temperature with decreasing time offers acceptable strength to regular sintering. Raising sintering temperature with decreasing time is suggested to facilitate chairside restorative reconstruction.