Grinding the intaglio surface of yttria partially- and fully-stabilized zirconia polycrystals restorations: Effect on their fatigue behavior

Nanoparticles and Their Application in Prosthetic Dentistry

“…When unstabilized zirconia is heated above the phase transition temperature and cooled at room temperature, its crystal structure changes from the tetragonal phase to the monoclinic phase. Zirconia does not have sufficient mechanical strength in the monoclinic phase, so stabilizing oxides such as Calcium Oxide (CaO), Magnesium Oxide (MgO) and Yttrium Oxide (Y2O3) are added to its composition in order to keep it partially stabilized in the tetragonal phase at room temperature (79,80).…”

“…This increase in volume can provide high mechanical strength to the material by forming a compressive stress layer that absorbs energy and stops crack formation and propagation. However, the increase in stimuli can also create a negative effect by causing excessive cracks and a decrease in the strength of the material (79)(80)(81). Compared to the first and second generations, the third generation zirconias, which contain up to 53% cubic phase ratio, have lower hardness and strength than the previous generations due to the reduction of the tetragonal-monoclinic phase transformation ratio that occurs with stress in the zirconia (86).…”