There have been profound advances in the application of zirconia dental ceramics in restorative dentistry establishing it as material of choice for tooth-colored, all-ceramic systems suitable for crowns and bridges, root posts and implants. The success of the first generation zirconia, i.e., 3Y-TZP, lies in the ability to exert stress-induced (t-m) transformation toughening mechanism. However, the 3Y-TZP`s tetragonal phase metastability has a detrimental side since allowing spontaneous low-temperature degradation (LTD) or ageing of ceramics. Recently, new generations of high-translucent zirconia grades with superior aesthetics were launched to comply with the full-contour monolithic paradigm cancelling out the veneer overlaying. However, the increase in yttria content (i.e. 4 to 5 mol.%) leads to partially stabilized tetragonal crystal lattice, which in turn increases translucency and resistance towards LTD at the expense of decreased mechanical strength since the t-m transformation is restrained.
The present lecture will report on some translational research progress showing how this diverse microstructure-property relationship of the yttrium-doped dental zirconia family can govern its performance in vitro as well as in vivo, determining suitable processing methods and laboratory procedures, such as airborne-particle abrasion (APA) and regeneration firing, which all can have pronounced effect on the mechanical strength and reliability. Finally, the prospects and challenges of entering the field of additive manufacturing workflow for dental zirconia will be discussed with the ultimate goal of enabling the fabrication of custom-made prosthetic options with improved functional (aesthetics) and structural (strength, toughness) properties. In order to succeed, an alternative manufacturing and sintering workflow enabling fabrication of multimaterial defect- and stress-free nanoscale microstructures needs to be established.