Characterization of a New 3.5 mol% Yttria Stabilized Zirconia

Objectives: To evaluate the density, phase content, grain size, translucency, and flexural strength of a new 3.5 mol% yttria-stabilized zirconia (3.5YSZ), and to compare its properties with those of commercially available dental 3YSZ and 4YSZ.
Methods: Sixty disc-shaped samples (Ø18 x 3 mm) were prepared from the 3.5YSZ powder, using the cold-isostatic pressing method (250 MPa). The samples (n = 10) were conventionally sintered with different temperatures (1300°C, 1350°C, 1400°C, 1450°C, 1500°C, and 1550°C). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied for phase content and microstructure analyses. Density, biaxial flexural strength, and translucency were also measured.
Results: The 3.5YSZ samples were densified (>99.8%) when the sintering temperature reached 1450 °C. The cubic phase content and grain size increased with the increase of the sintering temperature. The optimal values for translucency parameter (TP) and biaxial flexural strength (S), 33.76±0.74% and 1064±90 MPa, respectively, were reached at 1500°C.
Conclusions: 3.5YSZ could achieve higher TP values and similar flexural S relative to 3YSZ while achieving similar TP values and higher flexural S compared with 4YSZ. 3.5YSZ collectively possesses the high strength of 3YZS and similar translucency of 4YSZ, demonstrating an excellent balance between strength and translucency, and a potential application in restorative dentistry.