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Zirconia

What is Zirconia?

 

Material: 

Zirconium Dioxide (combined with a variety of other materials) was first used as a hip joint replacement material. However, in later years, research efforts converged more upon the development of zirconia-yittria ceramics combinations commonly known as Tetragonal Zirconia Polycrystals (TZP). In 1990s, Zirconium material was used as endodontic posts and as implant abutments. This heralded the use of Zirconium in to dentistry.

 

Aesthetics:

With a variety of translucencies in Zirconia it is possible to achieve life-like crowns which will match perfectly with your existing teeth. Even more enhancements can be achieved by adding porcelain to the Zirconia if required.

With pure white as a base colour (metal based crowns all have a grey metal undertone) Zirconia is the ideal material to build a crown on.

Zirconia crowns do not leave a black line along the gum-line like metal based  crowns do.

 

Biocompatibility:

Zirconia is currently the most inert dental material on the market. It has absolutely on interaction with the human body or bodily liquids.

Zirconia is not reactive in patients with metal sensitivities.

Studies have proved that there is less bacterial colonization around Zirconia prosthesis than metal or other material based crowns.

The cements used for bonding Zirconia to the tooth are less susceptible to triggering sensitivities in patients.

 

Strength:

Zirconia varies in strength according to the amount of Alumina in the raw product mix. Zirconium disks consist of the following, on average:

Zirconium oxide (ZrO2) + Hafnium oxide (HfO2)+ Yttrium oxide  (Y2O3) 99%

+

Aluminium oxide (Al2O3) in varying concentrations (Less than 0,25%). To achieve higher translucency less Al2O3 is included in the product mix. This however means that a certain amount of strength is sacrificed for this translucency. (The strength of the most translucent Zirconia is still many times stronger that the average human tooth.)

Zirconia crowns can be up to five times stronger that a porcelain fused to metal crowns.

Material Flexural Strength Comparison Chart

 

Thermal conductivity:

Zirconia has a very low thermal conductivity coefficient. This means that a Zirconia crown will not conduct heat or cold as easily as a metal based crown will, providing insulation for sensitive roots.

 

Radiopaque:

This characteristic of Zirconia enables your Dentist to examine a crown under X-ray or CBCT scan and to determine if there are problems with the underlying root/tooth.

 

Practicalities:

Because of the strength of Zirconia, less tooth surface needs to be removed to provide space for the crown.

The majority of Zirconia crowns are manufactured using CAD CAM systems. This makes the design and manufacturing of these crowns much more accurate and if placed properly, with less chance of failure over the long term.

The durability of the material and the accuracy of CAD/CAM manufacture makes Zirconia the ideal crown material for implant based prostheses.

 

Affordability:

In days gone by zirconia crowns would have been significantly more expensive than metal based crowns.

This is no longer the case. A full Zirconia crown should not be more expensive than a porcelain fused to metal crown.

The number of Zirconia manufacturers has increased significantly in recent years thereby increasing competition in the supply chain and reducing raw material prices significantly.

 

Origin of Zirconia:

It is important that you try and establish the country of origin of the original Zirconia disks. Metal Free Dental only uses Zirconia manufactured in Germany as, in our experience, material originating from other countries has proven to fail over a period of 18 months +.

 

Disadvantages:

Hardness: Zirconia, as stated above is several times harder than a human tooth. While this has many advantages, it is vital that the crown is prepared properly prior to fitment. The crown must be glazed prior to fitting as this will prevent undue ware of the opposing tooth.

 

Standard Zirconia

Indications: Full strength, limited translucency, 35%, suitable for cases where dentine or underlying material is dark and needs to be hidden. Single cronws and up to 16 unit bridges.

 

High Translucent Zirconia

Indications: Full strength, 40% translucency, suitable for single crowns and up to 16 unit bridges, cutbacks for porcelain application for higher aesthetics, full anatomical restorations.

 

CubeX2

Indications: 75% strength, ultra high translucency 49%, suitable for single up to 3 unit bridges, anterior application, full anatomical.

 

Material comparison chart

 

 

Bending strength chart

 

Material Flexural Strength Comparison (Mpa)

Zirconia Highlighted (approximate) 

 

 

 

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