What is Zirconia?
Zirconium dioxide (ZrO2), also known as “Zirconia” or “white steel,” is a white crystalline oxide of Zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the rare mineral baddeleyite. The high temperature cubic crystalline form is rarely found in nature as mineral tazheranite (Zr,Ti,Ca)O2 (and a doubtful mineral arkelite). This form, also called cubic Zirconia, is synthesized in various colours for use as a gemstone and a diamond simulant.
Thanks to its propeties, this ceramic material is used to create substructures in cosmetic dentistry to give crowns and bridges a whiter brighter more translucent quality. Zirconia is preferred for various medical applications including strong long-lasting artificial hip joints and, in case you’re wondering, it is 100% biocompatible, so you can rest assured in this regard.
Zirconia’s history in dental medicine
Since the 90s, Zirconia is considered one of the best ceramic products on the market for dental reconstructions. Keep in mind that this material is increasingly used in the field of dentistry since the beggining and it is estimated that between 15,000 and 20,000 Zirconia structures are made each day worldwide, this confirming its quality.
Why is Zirconium oxide one of the best choices in terms of dental restoration? The answer is very simple: because is esthetic, strong, pure, biocompatible and capable of being used for single and long span dental bridgework.
Zirconia’s characteristics in terms of dental restoration:
- Excellent biological compatibility: absolutely bio-inert.
- Outstanding physical and mechanical qualities:
- Hardness (Vickers) 1200 HV
- Compressive Strength 2000 MPa
- Bending Strength 1000 MPa
- Modulus of Elasticity 210 GPa
- Tensile Strength 7 Mpavm
- Wear characteristics (Ring on disc) <0.002 mm 3/h
- Absolute corrosion resistance: Ringer's solution 370C <0.01mg/m2x24h
- Very small particle size: <0.6ym
- No glass phase for particle binding
- Extremely high density
- Porosity: 0%
- Purity (Zr/Hf/Y): 99.9%
- Translucence of the framework material makes excellent cosmetic results possible
- Equivalent fit to precision gold castings: edge opening 20-50 ym. Precludes the need to use adhesive cements.
- Zirconium oxide is manufactured and optimized industrially so that the material qualities remain unchanged through the complete production chain.
- Optimal material for crowns: tasteless, radiopaque, no pulp irritation because there is no need to use adhesive cements and minimal invasive preparation by dentist.
In wich way is Zirconia useful in dental medicine?
The dentists around the world choose this material, placing an implant of Zirconium oxide rather than a metal one because Zirconia implants are more stable from a mechanical point of view, besides that have opened the possibility of a new generation of color dental implants.
Zirconium oxide can be used in many ways, but the most common application of it is to develop dental veneers, crowns, inlays, though today prosthesis can be made of 14 pieces.
Forming the core of each crown, this material provides the cross-link that bridges the gap of missing teeth. Thanks to the extreme accuracy of the crown fit, the crowns can be cemented with biocompatible dental luting material, this way avoiding the use of an invasive procedure of etching the tooth with acid and injuring the pulp or nerve of the tooth. This latter procedure often times results in the pulp dying and necessitating root canal therapy.
Comparation with the competition
OK, Zirconia might be one of the best choices, but it is the best compared with other full ceramics?
This unique ceramic material primarily stands out due to its high crack resistance. As you migh guess, crack resistance is the resistance with which the material counteracts the spreading of cracks. Well, the unusual feature of Zirconia in comparison with other ceramics is that at the appearance of a high-tension area a transformation of the crystal structure can take place.
In addition to that, Zirconium oxide stands out again regarding the characteristic of bending strengths, considering that while conventional glass ceramics show results of 100-200 Mpa and aluminum oxide ceramics lie in the area of 400-600 Mpa, Zirconia reaches a bending strength of over 1000 Mpa.
On the other hand, there are also some risks including radioactivity, considering that Zirconium may contain a certain number of radioactive isotopes, the activity of which may lead to an increased chance of various oral cancers.
However, this shouldn’t be a concern, because the Zirconia used in implants has extremely low radiation emission levels, and manufacturers of these are required to produce a declaration of radioactivity for their Zirconium based dental products.