You can think of a dental crown as a heavy-duty filling. A dental crown holds the whole tooth together when a simple filling wouldn't be enough. A crown is usually 2mm thick and can be either full porcelain, porcelain fused to a metal allow, or a full metal alloy crown.
Having a dental crown applied is a more invasive process than veneers, as more of the tooth needs to be ground down in preparation. But crowns do provide more protection to the tooth and are used when the damage is more severe. In the case of heavily decayed teeth, the tooth may need to be built up first before the dental crown is applied.
Because the dental crown holds the entire tooth together like a heavy-duty filling, dental crowns are often used in the case of root canals, and very heavily filled teeth.
