Fillings can be made from various materials. The materials generally used for fillings are "silver" or composite resins ("tooth" colored fillings.) Fillings are good for fixing small to medium sections of a tooth where a cavity has occurred. They are not good for repairing cracks, broken cusps, extensive decay or severely damaged old fillings. There has to be enough of the natural tooth remaining to support a filling. If insufficient natural tooth remains, a crown is typically the only answer.
I have a defective filling and have been told I need a crown. My tooth does not hurt. Why should I have a crown done now?
Often times, it is tempting to leave well enough alone when you are told that you have a condition that needs attention and you feel just fine. Leaving well enough alone can be a mistake when you are taking about your health and your teeth. Here's why:
A tooth that has a defective filling is a tooth that has bacteria and fluids seeing into it. Acids produced from the bacteria can eat away at the natural tooth that surrounds the filling. It can eat away the tooth under the filling, eventually reaching the nerve and blood supply. Once the nerve and blood supply is contaminated by the bacteria, the nerve will begin to fester, drain toxins out the end of the tooth and eventually produce an abscess. Often times, this is painful. Once an abscess has formed, a root canal must be done to remove the bacteria. The abscess is drained, and the nerve and blood supply inside the tooth are removed. A tooth that has had a root canal becomes dried out and brittle (think of a dried out twig, that snaps in two if you try and bend it) and requires a crown.
So, when a crown is recommended it is a good idea to have it done before root canal therapy is needed too. It can save you time, pain and money in the long run.