If the content of yttrium oxide as stabilizer is appropriately increased (5 mol %) in zirconia ceramics, the cubic phase zirconia crystal becomes the main crystal phase of the zirconia material, so the semi-permeability is very good, so it is called "super permeable oxide". zirconium". At the same time, due to its low content of tetragonal zirconia crystals, lack of phase transformation toughening mechanism, low strength and toughness, less phase transformation occurs in the entire temperature range of sintering and cooling, and the material has almost no volume change. It is called "fully stabilized zirconia".
The ultra-transparent zirconia all-ceramic material launched in 2015 uses 5 mol% (9~12 wt%) yttria as a stabilizer (5Y-TZP), and the alumina content is less than 0.05 wt%, or almost no addition, and cubic phase oxidation The content of zirconium crystal is more than 70%, the content of tetragonal phase is less than 30%, the semi-permeability of the material is very high, and the super-transparent performance is achieved (studies show that the TP value of ultra-transparent zirconia with a thickness of 1.0 mm reaches more than 35), and the general bending strength About 500~600 MPa, fracture toughness 2.2~2.7 MPa.m1/2.
The semi-permeability of the fourth-generation zirconia all-ceramic material is almost close to that of lithium disilicate glass ceramics, and its aesthetics are very good, but its strength is better than that of glass ceramics. It is mostly used for single crown and veneer restoration of anterior teeth.