Crowns are tooth-colored caps that enclose an entire tooth. Dentists often use them to reinforce a weak structure or restore function to a tooth that is severely damaged by decay or trauma. Crowns are also used to hide discoloration and imperfections, lengthen a short tooth, close minor gaps between teeth, cover dental implants, replace large fillings, keep a bridge in place and restore a tooth after a root canal.
Crowns are made of porcelain, metal, composite resin or a combination of these materials. Metal and alloys make the strongest and most durable crowns, so they are often used for back teeth. However, all-metal crowns stand out. A good compromise is porcelain-fused-to-metal crowns, where the metal is covered by tooth-colored porcelain.
A bridge is a fixed device used to replace a single tooth. It is composed of abutment teeth (teeth on either side of the gap) and a pontic or artificial tooth in the middle. The dentist first prepares the abutment teeth by grounding them down to make room for the crowns. The crowns are then used to anchor the artificial tooth. Another type of bridge called a cantilever bridge is used when there are teeth only on one side of the gap. A Maryland bridge or resin-bonded bridge is attached by metal wings on either side of the pontic instead of crowns.