Low Temperature Degradation of Dental Zirconia Ceramics In Vivo

The biomedical grade 3 mol.% yttria partially stabilized zirconia polycrystalline (3Y-TZP)ceramics has established as a material of choice for all-ceramic dental restorations. This isdue to 3Y-TZP`s superior mechanical properties, chemical stability and aesthetics, as comparedto glass-based dental ceramics and metals. In addition, since demonstrating long-termmechanical stability and reliable osseointegration into the jawbone, 3Y-TZTP implants arenowadays increasingly gaining attention and hold significant potential for clinical andindustrial success. 3Y-TZP’s high strength and fracture toughness are governed by the stress-induced transformation (t−m) toughening mechanism, where under applied stress themetastable tetragonal phase transforms to monoclinic. However, 3Y-TZP’s tetragonal phasemetastability also has a well-documented, deleterious aspect known as low-temperaturedegradation (LTD) or ageing. The seminar will discuss the clinical relevancy of in vivo ageing of3Y-TZP in the oral environment, as compared to artificially accelerated in vitro hydrothermalaging extrapolations at 37 °C.