Dental porcelain (or ceramic) is safe for 'most' people, but the experts disagree on how to measure the toxicity of porcelain. One also has to take into consideration the the 'glue' used to bond the porcelain to the tooth, since it may contain fluoride or cytotoxic components. Excessive tooth reduction is required in order to fit porcelain.  Porcelain is therefore not suitable for thin restorations or for people who would like to retain as much as possible of their healthy teeth structure. 

 

Porcelain by itself is not hard enough to provide a chewable surface - therefore dental porcelain is strengthened with metals such as aluminum, zirconium or lithium disilicate (Li2Si2O5).  Although porcelains are inert, some components are released over time due to erosion. Disagreement exist regarding the toxicity of eroded components.

 

Lithium disilicate is a popular choice but research has shown that lithium disilicates are not biologically inert and that  lithium-disilicate materials exhibited cytotoxicity that would not be deemed biologically acceptable on the basis of prevailing empirical standards for dental alloys and composites.  Lithium disilicate crowns are composed of quartz, lithium dioxide, phosphor oxide, alumina, potassium oxide, silicon and other components.

 

Long term exposure to lithium causes thyroid and kidney function abnormalities.  Phosphor is extremely toxic and long term exposure to small quatities may cause liver and kidney damage.  Silicone causes Raynaud's syndrome and autoimmune reactions in people with certain HLA types.

 

Both aluminium and zirconium may cause auto-immune disease in the long run, just like any other metal. If a person has an immune response to aluminum, Biocomp laboratories will treat all aluminum as toxic, including porcelain strengthened with aluminum.  Clifford Consulting regards insoluble aluminum compounds such as aluminum oxide and aluminum silicate, used in many types of porcelain, as safe for all people. 

 

Porcelain can be used to fill cavities (for people sensitive to resin) as inlays, onlays or overlays.  The disadvantage of this approach is that excessive healthy tooth structure needs to be removed.

 

Porcelain is an indirect method of restoration.  An indirect restoration requires at least two steps:

• making the restoration

• fixing it in place with dental cement or bonding agent.  The toxicity of the agent also needs to be considered since toxins can be absorbed in the blood stream through the teeth.

 

Pure Porcelain

The restoration can be completed in one office visit using CAD/CAM systems, but can also be completed in more than one office visit when the inlay or onlay must be fabricated in a lab.

 

Porcelain Fused to Metal

To provide stability and strength to the crown, porcelain is sometimes fused to metal. PFM crowns are nothing but a hybrid between porcelain and metal crowns.

 

The framework of a ceramic restoration can be made from metal or another form of ceramic. The metal is usually an alloy of gold, platinum, palladium and silver, although stainless stell and other metals are often used. Most people are sensitive to palladium and silver. Many people are sensitive to platinum.

 

Sources:

http://www.biocomplaboratories.com/biocompatibility-Testing-Dental-Toxicity.html

http://www.ccrlab.com/