Dental crowns are classified under Fixed Partial Dentures. They can either be single crowns or bridges. Single crowns are cap like structures designed to create an outer coverage for clinically reduced teeth. They are used to cover teeth with large cavities, root canal treated teeth or esthetically unappealing teeth.
Bridges on the other hand are designed to replace single to short span areas of missing teeth. They are done by reducing teeth next to areas of missing teeth. The reduced teeth are then caped to support false teeth made to replace and the missing teeth.
Both crowns are bridges are often made out of metal with an outer coverage of porcelain aka Procelain Fused to Metal (PFM). With the development of dental materials, more esthetically pleasing materials like zirconia and millable ceramics can be used for crown and bridge fabrication.
Fixed Partial Denture Crown
Fixed Partial Denture Bridge