Long-time aging in 3mol.% yttria-stabilized tetragonal zirconia polycrystals at human body temperature

Long-term stability of an injection-molded zirconia bone-level implant: A testing protocol considering aging kinetics and dynamic fatigue

“…The observed penetration depth of 6-8 m after a hydrothermal treatment at 85 • C for 60 days is in accordance with extrapolated data from the nowadays available literature (Fig. 6, Table 2) [23,35]. However, some data (e.g.…”

“…However, some data (e.g. S = 0.5 m/y at 37 • C) observed for samples aged at body temperature indicate, that the performed aging procedure at 85 • C might not exactly correspond to 40 years of aging at 37 • C [35,36]. Finally, one has to consider that most of the available data were preferably measured on materials where a saturation level was reached in order to have a clear change from the monoclinic to the tetragonal phase [23].…”

Lifetime estimation of zirconia ceramics by linear ageing kinetics

“…Therefore, the flexural strength and toughness of Y-TZP ceramics can be strongly enhanced by this transformation toughening effect [1,2]. In the presence of water or humidity however, the transformation from tetragonal to monoclinic (t-m) zirconia can occur spontaneously, even at room temperature (low temperature degradation or hydrothermal ageing) [1,3]. This can lead to increased wear rates with the release of small zirconia particles in the surrounding environment, aesthetic deterioration, reduced mechanical properties and even catastrophic failure [1,[4][5][6].…”

Surface Degradation of Nanocrystalline Zirconia Dental Implants

“…The fact that we did not observe an increasing concentration of monoclinic phase after one year of clinical test could be understood within the framework of long-time aging studies of tetragonal 3Y-TZP at temperature of human body [25], [26]. The phenomenon of tetragonal to monoclinic transformation as detected by X-ray micro-diffraction and confirmed by SEM observations is considered being due to the surface exposed to humidity.…”