A crown, commonly referred to as a cap, is a dental restoration that completely covers a tooth. The crown is permanently cemented to the tooth with a dental cement or adhesive. It is used primarily to protect a tooth that has had significant damage, but can be used in other situations.
Indications for a crown:

Crack or fracture of the tooth
Large area of decay that destroys significant tooth structure
Large, failed existing filling
Teeth with a history of root canal therapy
Esthetic enhancement

Crowns can be metal, porcelain, or a combination of both. Most crowns today are porcelain, but there are occasions when metal (gold) crowns are indicated.

The crown procedure is a two visit procedure. During the first visit, the tooth is prepared, an impression is made that will be sent to the laboratory for fabrication, and a temporary crown is fabricated. The temporary crown is typically a custom made acrylic crown that is cemented to the prepared tooth using a temporary cement. Temporary crowns can come off, but are easily put back on, most often this can be done at home. Because temporary crowns are made of acrylic they can break as well. In these cases we simply make a new temporary crown. The second visit is usually very short. The temporary is removed, the tooth is cleaned, and the final crown is tried on and then cemented in place.

Crowns can last for many years, some over 25 years. On average a crown lasts between 5 and 15 years. This range is influenced by the patient’s hygiene, normal wear and tear, and any habits (clenching/grinding, ice chewing, etc.) a patient may have. Crowns are not permanent and may need to be replaced in the future.