Mechanical and optical properties evaluation of rapid sintered dental zirconia

The purpose of this study was to compare the effects of conventional sintering (CS) and rapid sintering (RS) on the mechanical and optical properties of different generations of dental zirconia ceramics. Five commercial zirconia ceramics were used for the CS and RS processes. The microstructure, phase composition, biaxial strength, 3-point bending strength, and Vickers microhardness of the zirconia after different sintering processes were studied. Weibull analysis was also used to check the structural reliability of the zirconia. The translucency parameter (TP) and the color difference (ΔE) were determined from the L*, a*, and b* values. The surface morphology of each specimen was dense, with no obvious pores or microcracks. The grain size of the RS group was smaller than that of the CS group. Between the two sintering processes, the same characteristic peaks were detected in the X-ray diffraction (XRD) patterns. There was no statistically significant difference (p > 0.05) in the biaxial strength, 3-point bending strength, or Vickers microhardness in terms of the sintering process. After RS, the Weibull modulus of the materials ranged from 9.3 to 19.3. It seems that the RS process affected the TP and ΔE values to some degree and depended on the zirconia generation. The RS process had no impact on the mechanical properties and produced smaller grain sizes than the CS process. The effect of the RS process on the optical properties depended on the type of material used. These findings should assist the production of dental zirconia restorations through the RS process, which saves time and energy.