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 root canal treatment, or when a large filling wears out. The larger the hole made by a cavity that has to be treated, the more likely a crown will be needed. Teeth are subjected to tremendous pressures. Crowns cover the weakened tooth, providing strength and protecting the tooth against breakage.
Restoring a tooth with a crown requires two separate appointments. During the first of these two appointments, any decay is removed from the tooth and it is shaped to accept the crown. Impressions are made. Finally, a temporary crown is placed to protect the tooth while the permanent crown is made. Between the two appointments, the crown will be made by the lab. They are typically made of either ceramic material, gold alloy, or high-strength porcelain over gold alloy. During the second appointment, the temporary crown will be removed and the permanent crown will be adjusted as needed and cemented in place.
This is an option for filling the space created by a missing tooth. Dental bridges create a spacer tooth, which is formed to fill the space by utilizing the teeth on either side of it for support, hence the name "bridge".