Do you have a bad taste or metallic taste from a tooth that has a crown on it? The cause of this is usually a leaking crown.
Crowns leak because of breakdown of the cement that holds the crown in place, tooth decay or a poor fitting crown.
When you have a leaking crown, get it looked at by a dentist ASAP. It means that saliva and bacteria are seeping in between the crown and the tooth, which will lead to decay of the tooth. By the time you have this metallic taste, it is likely the decay is severe, which could mean the tooth must be extracted. The longer you leave it, the worse the situation will become.
If the crown is part of a bridge, this complicates matters much more. A problem with one tooth affects the entire bridge, making you effectively losing multiple teeth.
When you see your dentist, they will start off by taking an x-ray. Unfortunately, the x-ray cannot see through the crown, especially in older style crowns with metal inside. To accurately assess the tooth, it will need to be removed. Removal of a crown is one of the most tiresome things to do in dentistry. The porcelain is difficult to drill through and we also need to be careful not to drill your real tooth.
After the crown is removed, then the dentist will be able to see the condition of the tooth and advise whether a new crown is appropriate. A root canal and post may be required before the new crown is made.