Zirconia is another name for zirconium dioxide (ZrO2), an oxide of the metal zirconium. Zirconia blocks and discs are used by dental laboratories to mill zirconia copings, frameworks or full contour zirconia crowns and bridges. These blocks are formed under pressure from zirconium oxide powder stabilized with yttria, plus additional additives for bonding and translucency. This amazingly strong and biocompatible space-age material has been in use for nearlytwo dozen years in some of the and other industrial and medical applications.
Zirconia restorations offer function, esthetics, longevity, and gingival health, and the restoration of choice for nearly all cosmetic dentists today because they are metal free, esthetically translucent, and stronger than ANY other restoration material. A zirconia restoration is metal free. Some patients prefer not to put any metals into their bodies, which tend to *leach off* from some metal restorations and enter surrounding tissues and the blood stream.
How is zirconia block made ?
The first operation is the axial pressing of the zirconia. Products are manufactured in standard shapes like discs, cylinders and blocks according to market requirements. It is however possible to comply with our customer's specific requirements and produce customized product shapes and dimensions.
Isostatic pressing method:
After axial pressing, during which the semi-finished parts are given their necessary consistency, an isostatic pressing process is performed on all the products. The isostatic pressing process ensures all parts have a homogenous density and shrinkage distribution. This guarantees that during and after the sintering process, the products will always have extremely constant material characteristics.
Mechanical processing method:
Following the isostatic pressing process, the semi-finished parts can be shaped or machined to achieve the preferred geometry in accordance with product specifications.
During this process, the semi-finished parts are sintered at a specific temperature that optimizes the subsequent processing stages. Specific, computer controlled kilns are used for the heating up, dwell and cooling down phases.
The shrinkage factor of each production batch is carefully determined in our laboratory. The use of this shrinkage factor ensures that during final sintering, finished parts will have the dimensions required.
Why use zirconia – is this clinician driven or manufacturer driven?
The use of zirconia copings is driven by improved esthetics, biocompatibility, and durability as compared to PFM.