Blog | Camarillo Smiles | Dentist Camarillo CA

Camarillo Smiles blog has the latest in dental news and happenings. To learn more call (805) 388-5700. Your Dentist Camarillo CA.

When Good Crowns Go Bad

The Dreaded Black Line around a Crown


We have all seen smiles that you know have crowns in the front. You look at them and say to yourself that something is not natural. Many times, it is the dreaded black line, the dark rim of gum tissue that gives it away. The black rim of gum tissue does not occur around natural teeth, only around teeth that have been crowned.

What Causes the Dark Line?

The dark line is associated with an old porcelain crown. This style of crown is referred to as a porcelain fused-to-metal crown because it has tooth-colored porcelain baked onto metal. This had been done for strength for years. The dark line originates from the edge of the crown where the porcelain and the metal meet at a knife-edge at the gum line. At the knife-edge, a very thin amount of the metal always shows. One of the illusionary techniques dentists have used was to hide the thin dark line under the gum line. Over time, the gum tissue would recede and expose the dark line. In some patients the dark line would show through the gums and make it appear dark as well.

How Do You Get Rid of It?

The only way to eliminate the esthetic problem is to replace the crown. When replacing just one single crown in the front, you should expect that it might take more than one try-in of the new crown before it is permanently cemented into place. Because your central incisors are the most prominent teeth in the mouth, matching them is the most difficult esthetic challenge. Only the best dental technicians are able to mimic one central incisor tooth next to another.

What Are Some of the Replacement Crowns Like?

Some of the clever ways dentists and dental technicians have been able to mimic natural teeth is through the new advancements in dental materials. The all-tooth-colored ceramic crown is the latest technological advancement dentists have to recreate natural teeth. In comparison to a porcelain fused-to-metal crown, an all-ceramic crown does not contain any metal, thus no dark line can appear.

Some advantages of all-ceramic crowns are as follows:


  • High esthetics
  • Excellent fit
  • If gum recession occurs, there is no dark line

Crowns often need to be replaced after several years of service for esthetic or functional reasons. With the growing esthetic awareness of patients and the available ceramic technology, this type of re-treatment is becoming more common in the dental office.