Crowns are full coverage restorations that are used to cover a tooth that is too broken down to be restored with a filling. They are most commonly done after root canal treatment, or when a large filling wears out. The larger the hole made by a cavity, the more likely a crown may be needed. Keep in mind that the jaw muscles are some of the strongest in the human body and teeth are subjected to tremendous pressures. When teeth are weakened due to cavities or cracking, a crown can cover the weakened tooth, providing strength and protecting the tooth against breakage. A broken or cracked tooth is a far more serious matter and much more difficult to treat. Crowns prevent this, as well as providing an esthetic result.
It takes two appointments to restore a tooth with a crown. In the first, any decay is removed from the tooth and it is shaped to accept the crown. Then an impression is made of the tooth for use in fabricating the crown. Between the two visits the crown is made by a dental laboratory, usually of high-strength porcelain over gold alloy, all ceramic material, or gold. During this time a temporary crown is worn. At the second visit the temporary is removed and the permanent crown is cemented in place.