Crowns are used to restore badly decayed or fractured teeth.
A crown (often called a cap) covers the tooth and restores it to its original shape and size. Decay is removed and cleaned from the tooth and a highly accurate impression or mold is made of the prepared surface. This mold is used to create a model of the tooth which is then sent to a special laboratory that will create a gold or porcelain (tooth colored) crown. The crown is then cemented onto the prepared surface of the tooth.
Crowns are incredibly strong due to the fact that they are created in a laboratory. Crowns protect and strengthen the remaining tooth structure. In the hands of a skilled dentist, a crown will fit almost perfectly onto the prepared surface of the tooth, reducing the size of the seam between the crown and the tooth. This helps keep decay from eventually occurring under the crown.
Crowns should be placed before the tooth is so decayed that it may fracture. This can often help prevent the expense of root canal therapy in the future. It can also prevent the possibility that a fractured tooth may need to be removed, requiring the expense of a bridge or implant to replace the missing tooth.
Crowns are excellent restorations and have few disadvantages. They are highly durable, but they will eventually need to be re-cemented or replaced due to normal wear. Occasionally, a tooth may still need root canal therapy after being crowned. However, this indicates that the interior of the tooth was already sick (infected) and would have eventually needed root canal therapy anyway. A patient must still maintain proper oral hygiene to ensure the long term success of the crown. In the event that a tooth is so decayed or fractured that it needs to be removed, the best alternatives to a crown are bridges and implants that replace the missing tooth.