A crown (some people call it a "cap") is used to restore a tooth that would otherwise be in danger of breaking. It covers and protects the entire tooth. A dental bridge is used when there is a tooth missing. It usually involves putting a crown on each tooth on either side of the missing tooth, and then a false tooth or teeth is suspended between the crowns. With a CEREC onlay or crown the procedure is done in a single appointment, start to finish.