A crown is a restoration that covers, or "caps," a tooth to restore it to its normal shape and size, strengthening and improving the appearance of a tooth. Crowns are necessary when a tooth is generally broken down and fillings won't solve the problem. If a tooth is cracked, a crown holds the tooth together to seal the cracks so the damage doesn't get worse. Crowns are also used to restore a tooth when there isn't enough of the tooth remaining to provide support for a large filling, attach a bridge, protect weak teeth from fracturing, restore fractured teeth or cover badly shaped or discolored teeth.
  
  To prepare the tooth for a crown, it is reduced so the crown can fit over it. An impression of the teeth and gums is made and sent to the lab for the crown fabrication. A temporary crown is fitted over the tooth until the permanent crown is made. On the next visit, the dentist removes the temporary crown and cements the permanent crown onto the tooth.