mouth and dental disorders
Dental Appliances
Bridges, Crowns, and Implants
The replacement for an extracted tooth may be a bridge or an implant. Severely damaged teeth may have a crown placed over them. Abridgeis a fixed partial denture in which teeth on either side of the missing tooth are covered with crowns. A bridge is made up of false teeth that are fused together and then attached to a crown that is cemented to natural teeth. A bridge is permanently attached and cannot be removed. More than one bridge can be used to replace missing teeth. Acrownis a cap (restoration) that fits over a tooth. Getting a properly shaped crown usually takes two visits to the dentist, although sometimes more visits are needed. On the first visit, dentists prepare the tooth by tapering it slightly, take an impression of the prepared tooth, and put a temporary crown on it. A permanent crown is then made in a dental prosthetics laboratory, using the impression. On the next visit, the temporary crown is removed, and the final crown is permanently cemented onto the prepared tooth. Many dentists now use digital scanners and crown-milling devices that help them design and mill a crown for same-day placement. Usually, crowns are made of gold, ceramic, or porcelain fused to a metal structure. The porcelain coating can be used to mask the color of the metal. Although porcelain is harder and more abrasive than tooth enamel and may cause wear on the opposing tooth, newer ceramics are less apt to do so. Crowns made entirely of porcelain or similar material have a slightly greater tendency to break than do those made entirely of metal. Implantsmay be used to replace missing teeth. If people do not have sufficient healthy bone in their jaw, bone grafts can be done to create an adequate bed for the implants. Implants are metal fixtures inserted into the jawbone. The metal is a special alloy to which bone cells can attach. After a period of time, usually 2 to 6 months, the implant becomes solid with the bone, and a post is attached. Then an artificial tooth (crown) or teeth (from a partial to a complete set of dentures) are attached to the post. The resulting tooth or teeth can handle the force of normal chewing. Implants are considered more desirable now because they do not decay and they offer a fixed solution to removable partial dentures. People must keep the area around the implant very clean to prevent infection. 