In the case of a broken tooth, or one that is very badly decayed, it is sometimes necessary to replace the whole crown of the tooth.
One way is to first trim away all the decayed parts leaving only a tapered stump. An impression of this stump is made and from this a model is produced, on which the new crown, known as a jacket crown, is constructed. Porcelain is used to make crowns and the result can be indistinguisable from a natural tooth.
Alternatively, if the tooth is dead, a crown can be built up on a post of stainless steel or gold set into the hollowed stump. This is known as a post-crown.