Q. I have a crown on my front tooth with a black line around the top. My friend told me that her front tooth is a crown, but it doesn’t have the black line. What is the difference?
A. You have an old style, porcelain fused to metal crown. The line you see is the edge of the metal. Years ago this was the best technology, but things have definitely improved in dentistry. Today crowns can be made metal-free. Without the metal, light is able to pass through a crown as it does a tooth, and the ability to layer the porcelain allows the translucent edges of teeth to be mimicked. Not only is the dark line eliminated but also the monotone opaque look of the crown. They can be made of all porcelain or porcelain over a zirconium substructure. The all-porcelain crown may not be as strong as porcelain fused to metal, but on a front tooth it is as strong as it needs to be. The ability to build and replace teeth without metal is not limited to aesthetics. In studies, up to 80 percent of women are allergic to nickel. There are different grades of metal used in dentistry, but many of them do include nickel. It is nice to be able to eliminate this risk.
Ellen McOmie, D.M.D.
McOmie Family Dentistry
5999 Shallowford Road
Chattanooga, TN 37421