Many patients have this complaint. Until recently, crowns were done one of two ways: gold, or "porcelain fused to metal." The porcelain fused to metal crowns have been the standard way to make a white, or tooth colored crown, for many years. The porcelain is baked onto a metal substructure. The metal was necessary for strength. Unfortunately, it is difficult to mask out the dark color of the metal. This results in porcelain that looks opaque or chalky. The margin of the crown (where the crown meets the tooth) has to be in metal. This is what causes "dark line at the gum look." Dentists would often try to hide this metal margin underneath the gum line. This results in the gum appearing dark in this area. Or even worse, if the gum recedes, the metal is exposed creating a very unattractive appearance.