Zirconium Oxide Crowns
Symbol for Zirconium is Zr
Under room conditions (25°C 298 K):
Silver like white colored,
solid Metal d-block element
Zirconium metal was first invented by Martin Heinrich Klaproth in 1789. In 1824, it was isolated by Jons Jakob Berzelius.
Known minerals of zirconium are zircon (ZrSiO4) and baddeleyite (ZrO2).
Zirconium output is obtained by reduction of ZrCl4 compound by magnesium and calcium. Zirconium material whose chemical characteristics and historical background is mentioned above is used routinely in the dental sector focusing on sense of aesthetics.
Zirconium became more preferred choice especially in front teeth restorations where both aesthetics and endurance are desired.
What are the characteristic of Zirconium Oxide Crowns
Color Match and Transulance:
Porcelain is a delicate material when used alone. It should contain a resistant material at its bottom part. In another words, a material other than porcelain should be included to the porcelain crown teeth.
When this material is metal, it appears to be matte and especially causes purple appearance of gums. The structure of natural teeth consists of enamel, dentin and dental pulp. Every layer has different color characteristics. When we wear a white blouse, it looks white as it reflects the light as white. It is also valid for the teeth. Different layers inside the teeth have differing luminous transmittance characteristics. The picture above shows the same teeth from different sections. It is hard to believe all pictures shows the same teeth.
Colors and layers seemed so different from each other. Some parts of the painted sections look white while other parts look blue. However, when we look to the whole of tooth, we see only one color. The layer on the cut teeth forms the base for the porcelain. This layer forms a light-proof, matte and gray barrier as it consists of metal. In Zirconium Oxide Crowns, this layer has more matching appearance as this layer is white and often closer to the original teeth.
Adaptation to teeth:
Can be prepared as a very thin layer as it is has a light resistance. Fully adaptable to teeth and gum. This prevents micro-leakage.
Zirconium is three times harder than iron in the table of chemical elements. It can easily be used at the back group teeth as its resistant enough for chewing pressure. It is especially suitable for full mouth crown. It is tolerant to occlusal force during function. Of course, it is needless to say that, patients should not crack nuts with these teeth.
Adaptation to Gum:
Unwanted purple gum appearance does not exist in zirconium oxide crowns when compared with metal supported crowns due to its full adaptation to gums as well as its luminous transmittance. Thin black line which appears due to reflection of metals at the margins that emerges due to wear of crowns does not occur in zirconium oxide crowns.
Use in the bridges:
Crowns that does not contain metals were used in the bridges due to their aesthetic advantages in the past however these attempts were not successful.
Using zirconium in the precision attachment dentures provide advantage in maintaining a hookless and natural appearance and smile in the patience giving important to frontal aesthetics.
It is a hygienic and non-allergenic material:
It is used comfortably especially to the patients with poor oral hygiene. Its adaptation provides easiness in maintaining hygiene.
I believe that zirconium currently having price disadvantage due to the fact that it is a new technology will become a routine procedure in time. When it was first used, metal backed porcelain application was an expensive procedure. However, its price became more reasonable in time.