A crown (sometimes called a cap) is usually needed when the damage to the tooth is too great to be repaired with a filling.
The crown essentially replaces the outer layer of tooth. The tooth is prepared by removing the outer layer of tooth structure from the sides and top of the tooth. A mold of the tooth is made, a temporary crown is fabricated and cemented in place, and a shade is chosen for the permanent crown.
There are several reasons why your dentist may recommend a crown.
1. A large cavity
When there is a very large cavity in the tooth, after the decay has been properly cleaned out, the remaining tooth structure can be very thin. Normal chewing may cause the tooth to fracture, so a crown is needed to protect the tooth.
2. A cracked or chipped tooth
If your tooth cracks or chips, a crown may be needed to replace the missing tooth structure. If an internal crack is suspected, the dentist may recommend a crown to prevent additional damage to the tooth.
3. Root canal treated tooth.
A tooth that needs a root canal usually meets conditions 1 or 2. Even if it does not, the access through the tooth necessary to perform the procedure will usually weaken the tooth, requiring a crown both for structural integrity and to seal off the tooth from infection.
After your temporary and permanent crowns have been cemented in place, you should not eat for 30 minutes to allow the cement to set. While the temporary is in your mouth, avoid eating sticky foods, as they may pull off the temporary crown. If the crown does come out, please save it and contact your dentist.