Traditional dental crowns are made of porcelain fused to a metal base. New technology allows for a crown made entirely of porcelain. This allows for much better esthetics than traditional metal base crowns. Because as once gums recede, as they tend to do with age, the metal will start to show around the gum line. However, for an all porcelain crown there is no metal and thus eliminating the gray line. Also, there is a lower chance of a metal allergy for the patient.