Zirconia is a polymeric material made up of 3 crystalline phases 1) Monoclinic 2) Tetragonal and 3) Cubic.
Zirconia is a ceramic material used for permanent prosthesis such as crowns and bridges. It has a good chemical properties, high mechanical strength, dimensional stability and toughness. Hence, it becomes a material of choice for posterior prosthesis and in patients having insufficient interocclusal space. Although there maybe certain disadvantages such as increased load on the jaw joint, and damage to the natural tooth.
Zirconia prosthesis are available from many countries and many brands. But essentially they are available based on the flexural strength and translucency. Higher the strength lower is the translucency. So as a clinician, we need to communicate the need for strength and aesthetics. The highest translucency is with 450 mpa of strength and the most opaque are around 1450 mpa strength.
Rules for Zirconia Crown
As a rule to remember in case of single unit upto 5 unit in aesthetic zone, 450 mpa monolith zirconia would give the highest aesthetics or the other option would be to have a zirconia coping with ceramic layering. Although this increases the changes of chipping.
For a full mouth case, where more than 10 units are required, a 1250 mpa monolith zirconia would give good aesthetics but excellent strength. To give a better aesthetics, a back cut on the incisal 1/3rd of the anterior teeth can be given and a ceramic build-up done. This gives high aesthetics and high strength but takes more time and hence is more expensive.
As a clinician more than the brand it is the technical sheet which we need to be aware of and communicate with the laboratory regarding this. For more information visit indentlaboratory.com
|Translucency vs Strength||Indian||European||Chinese|
|Opaque||1200 mpa||1450 mpa||1100 mpa|
|Translucent||1100 mpa||870 mpa||1100 mpa|
|Extremely Translucent||600 mpa||750 mpa||450 mpa|
Comparative Analysis of Zirconia Crown in various Countries.