Porcelain fused to metal crowns (or PFM crowns) can be referred to as full-cast crowns which has porcelain fused on most or all parts of the tooth. Metal alloys with a high melting temperature are used to fuse porcelain to the surface and preventing the metal from melting. This ensures the porcelain to bond without changing its color. When the tooth is prepared for such crowns, a large part of the tooth tissue gets removed making space for porcelain as well as the metal.