A dental crown is a customized tooth-shaped "cap" that is placed over a tooth - covering the tooth to restore its shape and size, strength, and/or to improve its appearance. The crown can (i) protect a weak tooth from breaking; (ii) restore tooth that has been severely worn down; (iii) cover misshapened or severely discolored teeth. Preparing a tooth for a crown usually requires two visits to the dentist -- the first step involves examining and preparing the tooth and the second visit involves placement of the permanent crown.