Role of 3Y-TZP grain boundaries in glazing and layering.

Objectives: Monolithic 3 mol% Yttria-stabilized tetragonal zirconia polycrystal or 3Y-TZP exhibits transformation toughening phenomena which is suitable for dental restorations with minimizing the risk of fracture and to decrease reduction of natural tooth. However, the staining/glazing or layering is required to achieve of a match with the optical properties of natural dentition. The hypothesis under examination is that the physical, chemical, and structural aspects of the 3Y-TZP grain boundaries after the staining/glazing or layering.

Methods: The three sintering temperatures of 1400 °C, 1500 °C, and 1600 °C were considered followed by vacuum annealed at 750 °C for 1 min; and air post-annealed at 750 °C for 1 min RESULTS: The initial sintering step in the fabrication of zirconia restorations plays a critical role in the outcomes of the subsequent stages of glazing and layering.

Significance: The current study revealed for first time the advantage of vacuum annealing by the presence of ferroelastic domain switching toughening mechanism.