A crown (often called a cap) is a restoration that covers the entire tooth above the gum line. Most teeth that need crowns have previously had large fillings and decay, and may even be badly broken. Most teeth that are treated with a root canal will also need a crown to seal the root canal. Sometimes crowns are made simply for aesthetic purposes. Crowns are made of porcelain, metal, or a combination of both. Porcelain crowns will be fabricated in a shade, or color, that matches your other teeth so it blends in nicely.
To prepare a tooth for a crown, a 2-2.5 mm layer of tooth structure is removed from the top and every side of the tooth. If there is an old filling or decay in the tooth, it is usually replaced with a filling called a “build up”. Once the tooth is the right shape for the crown, an impression will be taken to send to the lab. This way, the lab knows what shape to make the crown.
You will have a temporary crown on your tooth for the 2-3 weeks it takes the lab to fabricate your permanent crown. This means it takes two visits to make a crown: one to prepare the tooth and take the impression, and one to deliver and cement the permanent crown.