Technical reminder :

Zirconium: white metalZirconia: zirconium dioxideCeramic: polycrystalline structure resulting of a sintering. Yttrium: oxide Y2O3 (yttria)Zirconia frames are made from blocks partially stabilised:Y-TZP,under 2 state, CIP presintered, and HIP denseZirconia Y-TZPyttria tetragonal Zirconia polycristalCIP Zirconia : cold isostatic pressure, partially sintered, cold green zirconia, condensed by sintering after milling with a retraction of 20 to 30%Hip zirconia: hot isostatic pressure, hard zirconia condensed by heat.

Advantages :

Very good resistance to corrosion; no chemical reaction observed; no toxicity or allergy known; no bimetallism possible; no problems of dental plaque; no retention possible; very good gingival tissue tolerance thus the zirconia prosthesis looks very natural, emerging from a pink and healthy gingiva which let the light through; translucence close to the natural teeth; zirconia has been used for more than 20 years in orthopaedics.

Exploitation

Zirconia is the common word of the zirconium dioxide (Zr02). Zirconia is technical porcelain. Zirconia is found in natural state as ZrSi04 silicate (Alvit sand) or oxide ( baddeleyit or brasilit). Zirconia powder is purified by chemical reaction of solution flit. The minimal rate of zirconium oxide must be of 93,6%. In order to have a good stability yttrium oxide has to be added at an ideal rate of 5,15%. Zirconium dioxide crystals organise themselves in a crystalline structure. This structure can have a cubic shape with a scare side, this is the cubic stage. A shape of a prism with rectangular sides is the tetragonal stage. A deformed prism with plane-parallel sides is the monocline stage.

Only the tetragonal phase gives right mecanical property to the porcelain.