A crown is a gold, all porcelain, or porcelain and metal cap that is cemented or bonded to a core of tooth structure. The three types all have their place and advantages. Gold crowns are usually reserved for posterior teeth. They are very long lasting, very compatible with your gums and tissues, and don't break. Porcelain fused to a metal alloy crowns are very long lasting and durable, however they do have the potential to fracture. Hey should blend with your other teeth much better than a gold crown. All porcelain crowns have the best esthetics, however they also have the highest fracture rate. The material used should be chosen on an individual basis.
Crowns are typically used to restore a tooth's function and appearance after trauma, a root canal, after severe decay, or to prevent a crack from progressing. They also are used for strictly cosmetic purposes. A crown is also used as the final restoration over an implant.
Bridges are used to replace missing teeth. They can be either fixed or removable. A fixed bridge will use crowns to cement to teeth adjacent to the missing tooth and teeth. The goal is esthetics and function. They are cemented in, and act like real teeth. A removable bridge or partial can replace many or most teeth and is supported by adjacent teeth and the gums. Partials are usually less expensive than a bridge, the main fault being that they are not as secure.
A tooth must be reduced to accommodate a crown or several crowns for a bridge. Minor modifications must usually be made for a partial. An impression of the reduced area is made and sent to a lab with instructions for size, shape, color and material. A temporary crown is cemented, and acts as a natural tooth while the crown is being made. With proper care, including brushing and flossing, crowns and bridges are both esthetic and should provide very good chewing function.