Zirconium and zirconium oxide ceramics in modern dentistry

Various types of ceramics are widely used in dental prosthetics. One of them is zirconium oxide ceramics. Currently, it is the strongest white material used in dentistry which is characterised by good aesthetic properties and excellent biocompatibility.

Zirconium is a metal represented by the symbol Zr in the periodic table of elements and located next to titanium (Ti). It belongs to the titanium metal family (titanium, zirconium, hafnium). It is not found in its pure form in nature. It is extracted from the minerals zircon (ZrSiO4) and baddeleyite (ZrO8). Most of these minerals, about 80%, are mined in Australia, South Africa and the USA. It is also found in Brazil, Russia and China. Baddeleyite contains particularly high levels of zirconium oxide but is quite rare and is mainly found in Brazil and Florida (USA). Zirconium ceramics are obtained through the Kroll metallurgical process. At the end of the process, white zirconium oxide powder is obtained (which is no longer a metal, but a ceramic). Zirconium oxide is used in various fields: in the manufacture of aircraft, engines, paints, electronics, etc. In jewellery, it is used to make artificial diamonds. Various metal alloys (chromium-cobalt, nickel-chromium, gold-platinum-palladium, etc.) have long been used in the manufacture of dental prostheses.

Dental prostheses in the mouth are in constant contact with saliva and are exposed to acids and temperature changes. This leads to corrosion, i.e. the decay of metals, and the ions of these metals enter the digestive system. Once in the human body, they can form various compounds and influence biochemical processes. This is particularly emphasised in homeopathy. Therefore, when performing dental prosthetics, it is recommended to avoid using different types of metals in the mouth. Zirconium, like titanium, from which dental implants are made, is a highly biocompatible and corrosion-resistant material. Zirconium oxide ceramics are particularly suitable for people with allergies and those looking for healthier alternatives.

Complex milling machines mill dental prostheses from zirconium oxide which are then subjected to high temperatures and become very strong. Zirconium oxide products have a fracture resistance of up to 1,500 MPa and are at least three times stronger than prostheses made from other types of ceramics.

Dental prostheses can be manufactured using only zirconium oxide or by coating it with a more transparent, more aesthetic but also weaker type of ceramic (feldspar or glass ceramic).

Natural teeth are loose in the bone because they are surrounded by ligaments that act as shock absorbers. Dental implants fuse directly with the bone and are almost immobile, prostheses made of weaker ceramics (e.g. metal ceramics) are therefore more likely to break. Such complications are extremely rare with zirconium oxide crowns. Zirconium oxide ceramics are also a more practical choice for fabricating dentures when people grind their teeth due to stress.

Since no metal prosthesis framework is used (as in the case of metal-ceramic prostheses), zirconium oxide ceramics allow more light to pass through, depending on their thickness. This makes artificial teeth look much more natural. With the right thickness, zirconium oxide crowns perfectly mask even very dark teeth or metal pins.