Dental crowns are designed to give your tooth an entirely new surface, covering up all visible parts of the tooth with a sheath of advanced ceramic material. This material looks like tooth enamel, but it’s not vulnerable to the acids produced by oral bacteria, so it doesn’t develop cavities. It’s also really smooth, so it’s hard for bacteria to hold on, and easy to clean.
But does that mean that a crowned tooth is invulnerable to decay? Ideally, yes, but, practically, no.
Poorly Placed Crowns Increase Risk
One way that you can get decay in a crowned tooth is if the crown itself is poorly fitted. If the crown creates a substantial shelf where food and plaque can accumulate, you are more likely to get decay at the edge of the crown, even if you clean carefully and thoroughly.
It’s even worse if the crown doesn’t make a tight seal with your natural tooth. The area between the crown and the tooth can be colonized by oral bacteria, which can cause decay underneath the crown.
Crowns Can Fail
A properly placed crown will do a good job of preventing decay until it fails. There are several ways crowns can fail. They can develop cracks, and older crowns can even wear through.
When the integrity of the crown is compromised, oral bacteria can find their way into your natural tooth, causing decay.
Roots Are Still Vulnerable
Although crowns cover the top of the tooth, the entire root of the tooth remains exposed. Ideally, this should be covered by your gums and even your jawbone, but if you have receding gums due to gum disease or other causes, parts of the tooth that shouldn’t be exposed can become exposed. This can be a cosmetic problem if you have porcelain-fused-to-metal crowns, which have a metal margin, but it can also lead to bad cavities because the tooth root is especially vulnerable to decay. It’s made of cementum, not enamel, and oral bacteria can break down cementum easily.
You can also develop decay or infection from inside the jaw if one or more nearby teeth are infected. The bacteria travels through the jawbone and enters the crowned tooth through the root canal.
Treating Decay in Crowned Teeth
If your crowned tooth has developed decay, something will have to be done. If the crown is in good shape and the decay isn’t too extensive, we can treat decay with a regular tooth-colored filling. This isn’t always an ideal solution, though, because it can create a poor seal with the dental crown that will need to be monitored closely for future problems.
If the problem is related to a poorly fitted or failed crown, we may have to remove the crown to remove decay. After all the decay has been removed, we will design and fit a new dental crown. It may be advisable to perform a root canal treatment on the tooth if it hasn’t been done already. Once a tooth has been prepared for a crown, it has less natural material to protect the interior chamber of the tooth, and any new decay is likely approaching that central chamber. It’s best to head off potential infection by removing the tooth pulp and filling its chamber.
Decay or damage to the tooth root can be more serious. If the root of a tooth is damaged, we may have to extract it and replace it with a dental implant. Dental implants are completely invulnerable to cavities. However, they can still develop a form of gum disease called peri-implantitis. This is the leading cause of failure for implants that have successfully integrated with your bone. Careful implant maintenance can help you avoid this problem.