Some dental crowns have a dark metal that is underneath the tooth colored porcelain . If the porcelain does not completely cover this dark metal, or the gums have receded and the metal is now exposed , then a dark ring will show. There are many ways to easily avoid this from happening . With the new materials that we now have available there's no longer a need to have any dark metal underneath the porcelain . In other cases, the edge of the crown, which is called a margin, can we placed just underneath the level of the gum line so that the margin will not show.
A dental crown, also called a cap, is a sheath that fits snugly over the entire visible surface of the tooth, essentially giving your tooth a new surface. This allows it not only to give the tooth an attractive appearance, but to add support and strength. Most importantly, the crown seals the damaged tooth, protecting it from harmful bacteria .All-porcelain crowns are slightly more attractive than PFM (porcelain fused to metal), crowns as they have a more natural luster, better color matching options, and will not show metal if your gums recede or if the crown experiences wear.