In order to fully exploit the advantages of our zirconium oxide-based restorative materials, we first need to understand the material and its manufacturing process, secondly, we need to recognize the importance of the shell design that supports the ceramic layer, and finally, the surface of the zirconium oxide must be treated to maintain its strength and achieve a good bond with the porcelain.
Material properties of zirconium oxide
Zirconium (Zr) is an independent element derived from the mineral zircon. Zirconium has extremely high corrosion and heat resistance and is often used in surgical instruments, crucibles and furnaces, mainly as a refractory material. Zirconium can also be cut into gemstones for jewelry, but most of the world's zircon is used in nuclear reactors.
Zirconium oxide is widely used in spacecraft components, certain abrasives and sandpaper due to its superior biocompatibility, especially in the field of dentistry, where its biocompatibility is better than that of titanium. The mineral form of zircon is mainly distributed in Brazil, India, Russia and the United States, but 80% of zircon comes from Australia and South Africa.
As a transition metal, zirconium oxide has excellent toughness and chemical resistance, making it an ideal material for dental restorations. In industry, zirconium oxide is called "ceramic steel" because its fracture resistance is similar to that of steel.
Zirconia's strength, biocompatibility, and light-transmitting properties make it a popular choice among the materials available to us.
Zirconia Manufacturing
Zirconium oxide can be made into a variety of shapes to suit different applications, with different grades of raw powder being used. For the dental industry, of course, medical grade materials are required. Purity, particle size, and uniformity all play a role in achieving the best light-transmitting zirconia base. If purity is compromised, impurities may appear in certain areas, which can affect the durability of the material.
On the left is a light-transmitting glass-ceramic crown, and on the right is a zirconia-based restoration with a more light-blocking framework.
All zirconia is not the same and compromises made by using lower grade powders, cheaper manufacturing operations and simpler pressing techniques are maybe risks we would not wish to take, as we construct more and more zirconia based work in our laboratories.
So (just to emphasise the point), if you want a more predictable zirconia with a homogenous density and a superior fired density, with even shrinkage then you will be looking for isostatically pressed material. It will save you time, money and heartache in the long run.
