Single unit prosthesis which fits on the prepared tooth to give it chewable and esthetic form and shape is called a crown, whereas, union of two or more crowns is called as a bridge.
Another best way to treat missing teeth is through fixed partial dentures. In this modality of treatment we take the support of adjacent teeth to replace the missing teeth. Number of adjacent teeth to be involved for support depends on number of missing teeth. The adjacent teeth have to be strong enough to give support to the bridge, otherwise more number of teeth have to be involved for more support.
Coming to the material aspect of crowns and bridges, the traditional way of replacing the missing teeth is through wrought metal crowns. It was followed by availability of metal ceramic crowns. In metal ceramic crowns the core component is made up of metal over which a layer of ceramic is coated, thereby it resembles natural tooth. The major disadvantage in metal ceramic crowns is that, the ceramic layer chips off leaving the metal exposed after using it for couple of years. As it has metal underneath, it doesn’t allow the light to pass through it thereby compromising the esthetics. So, these crowns are not primary choice for front teeth.
Full Ceramic/Zirconia crowns; these are completely made up of Ceramic/Zirconia. Different kinds/qualities of ceramic crowns are available, which depend on the quality of the crown. Ceramic crowns very much look alike natural tooth.
Many kinds of shades are available, to give the full ceramic crown similar natural look. The shade of white is selected though a shade guide. They are the most preferred crowns for those who seek quality because of its strength, appearance and longevity. They have a life span of 8-15 years or even more depending upon their quality and usage.