Crowns are full coverage restorations that are used to cover a tooth that is likely to break or is too broken down to be restored with a filling. They are most commonly done after a root canal treatment or when a large gilling wears out. The larger the hole made by a cavity that must be treated, the more likely a crown will be needed. Even after a filing is put in a large cavity a tooth is more likely to break. Keep in mind that the jaw muscles are the strongest in the human body. Teeth are subjected to tremendous pressures. Crows ride over 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 making for a nice smile.
It takes two appointments to restore a tooth with a crown. At the first appointment, 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 a crown. Between the two visits, the crown is made, usually of high-strength porcelain over gold alloy, all ceramic material or gold. During this time a temporary crown is worn and then removed at the second visit. Then the permanent crown is adjusted a needed, cemented in a polished for a beautiful new tooth.