A crown is a type of dental restoration that completely caps a tooth or dental implants. Crowns are used when a large cavity threatens a tooth's ongoing health. The crowns is usually affixed with adental cement. Crowns can be used to also improve the strength or appearance of teeth. Crowns are often used to for the following reasons:

• Dental Implants
• Endodontically treated teeth: protects teeth with root canals from fracturing.
• Abutment teeth for removable partial dentures
• Aesthetics (aesthetic dentistry)

Treatment

Crown preparation involves permanently removing much of the tooth's original structure, including some healthy and sound portions of the tooth. If there is not enough of the structure left for a crown, the tooth will need to built-up using resin or other materials. If the cost for build up is too pohibitive, the tooth might be extracted and replaced with an implant. A dentist prepares to crown a tooth by making an impression of a prepared tooth. Patients are then asked to return for a second appointment for the fitting. The crown is then fabricated, using a variety of possible materials:

• Gold
• Porcelain
• Porcelain fused with metal
• Leucite reinforced porcelain
• Alumina
• Zirconia

3/4 and 7/8 Crowns

The crowns fall roughly between an only and a full crown. Generally used for molars, these crowns preserve as much of the natural tooth structure as possible, giving the tooth added strength.

Prognosis

The average lifespan of a crown is 10 years, but they can last up t life of the patient with proper care.