A tooth that has old mercury fillings requires some upgrades in order to get the tooth to last.
Through the years, the definitive treatment on an old mercury-filled tooth has been to crown or “cap” the tooth. These days, because porcelain has come so far, and techniques so advanced, we are oftentimes able to restore the tooth with more conservative restorations that save more of the natural tooth. These are called onlays. I like to think of an onlay as a “mini-crown.”
The process of replacing amalgam fillings with porcelain onlays includes first removing the old filling and any cracks or decayed areas. (It is surprising how often we find decay under those old amalgam fillings.) Then we make a solid all-porcelain piece to fit the space and bond it into the tooth.
Of course, some teeth with mercury fillings are a little too far gone to fix with onlays, but we can generally save the tooth using a crown.
Here is a recent case where we were able to save a cracked tooth using a crown. The tooth directly in front of the one with the crown would be perfect for an onlay, primarily because it hasn’t developed any symptoms. A tooth that has already developed sensitivity to either cold or chewing can be difficult to bring back to “the land of the living.”
Don’t confuse porcelain with the lesser material called composite, which is a fancy word for plastic. Composite can be a great material, but generally should only be used in front teeth doing light duty or for very small fillings on back teeth.