Crowns are metal (gold) or porcelain (white) artificial covers for teeth. They are usually done to restore tooth function and esthetics of badly broken down, cracked or root canal treated teeth. They are also used to restore implants, as attachments for bridges or to cover discolored or stained teeth.
Bridges are appliances usually attached to teeth or implants on either side of a space created by a missing tooth of teeth. They consist of two or more crowns with a false tooth or teeth connected between. They are cemented in place and restore function and esthetics. The procedure is very similar to that of a single crown.
With proper care including flossing regular a crown can last five years or more. Jaw clenching or bruxism (teeth grinding) can shorten the life of the crown.