Zirconia Crowns and Bridges .
What are Zirconia Crowns?
Zirconia has been used in orthopedic surgery for years, and has proved to be highly bio-compatible. In Europe, Zirconia implants have been used for years to provide the ultimate in bio-compatability. Although titanium is incredibly strong and resilient, and has a good history of bio-compatability, it is not completely inert. With many millions of titanium implants a small minority of patients have suffered side effects of metal in the body . 
Titanium constantly releases metal ions into your body, and this constant exposure in certain individual sometimes triggers side effects which may include soreness, inflammation, allergies, and even autoimmune disease. Metal in the mouth also creates a battery effect - the saliva conducts the flow of electricity from one metal pole to another.
Now, the Zirconia manufacturers have worked on new crowns that are custom milled from solid blocks of Zirconia and baked at extremely high temperatures so that the completed crown is pretty near unbreakable. Zirconia is 100% biocompatible. It is inert, and the body does not reject zirconia so you don’t have to worry about allergies or adverse reactions.
Zirconia Crowns have several advantages of both traditional Gold Crowns and Porcelain.
Although Gold Crowns are well tolerated, last long and are a good technical choice, many consumers much prefer to have a natural effect that blends into the overall smile. Many also don't want metal in their mouths.
Cosmetic: Have you ever seen people with a large unsightly black line above their gums? Up until recently most crowns are Porcelain which is Fused to a Metal base. Over time, the metal begins to show more and more and the restoration can look opaque and monochromatic, with the tell tale dark grey line at the crown join.
The Zirconia Crowns not only look more translucent, but are much stronger than the Porcelain fused to the Metal posts. The Zirconia crowns can be up to five times stronger than a porcelain / metal fuse.
Less tooth Removal: In cases where their is not much room for porcelain build up - for example if an tooth abutment is already quite bulky, a Zirconia Crown can be used because if provides more strength in less volume than a porcelain crown.
Eventhough its more expensive , "you get what you pay for" .
