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Dental crowns

Dental crowns are permanent tooth covers that are cemented to chipped, cracked or broken teeth to improve their appearance and function.

Are the dental crowns supposed to turn black at the top of a crown and if this is expected, what can I do to get the black off?

Elisa Mello (New York, NY) on Sep 26, 2011
if your dental crown appears black after it was placed it may indicate that the crowns that were used have a metal as a base and are layered with porcelain on top. It could also happen with all-porcelain crowns under two circumstances. 1) there is a large gap between the porcelain and the tooth which has slowly attracted stains and, possibly, decay. 2) the tooth that is supporting the crown has slowly changed color, most likely as a result of a longstanding root canal. in order to take the black off, more than likely the crown needs replacing.
Steven Glassman (New York, NY) on Aug 29, 2011
This is a great question! When we see a black line near the pink gum line surrounding the crown, this is a metal collar that is part of the existing crown. This type of crown is called a 'porcelain fused to metal crown.’ The only way to remove this is to redo the crown with an all porcelain material that will be very cosmetically pleasing, matching the existing natural teeth and 'disappearing' in your smile. This way, it will really look like you were born with that tooth.
Michael Apa (New York, NY) on Aug 29, 2011
The black is from either the metal of the crown showing through or your tooth turning black underneath. In either case, no, this is not supposed to happen. If it is happening, the crown usually has to be replaced.
Christopher Baer (Aurora, CO) on Aug 29, 2011
They are not expected to turn black. A few different things could be going on here. It is difficult to diagnose without seeing you, but I would recommend you see a dentist to determine what is going on. If it is a metal-based crown, it could be the metal showing. If it is a metal-free crown, then it could be from something else used during the preparation portion of the tooth. It could also potentially be tooth decay.
Steven Bader (Newton Centre, MA) on Aug 29, 2011
It sounds like your current crowns have a metal base under the porcelain. This is very common. The black line you are seeing is most likely that metal edge. Usually there is little you can do to hide and uncovered metal margin. Many crowns are now made without metal, using only porcelain. Look for a dentist who has experience in cosmetic crowns. He or she should be able to guide you to the best solution. Good luck!
Marlen Martirossian (River Edge, NJ) on Aug 29, 2011
if the base of the crown is metal, gum recession exposes the gray margin of the crown. You can redo the crown with a metal-free capper.
Amanda Seay (Mount Pleasant, SC) on Aug 29, 2011
Crowns, in themselves, do not turn black. It is important to understand the differences in the types of crowns a dentist may place in your mouth. There are, generally speaking, two types of crowns. One is a porcelain fused to metal(PFM) crown which consists of a metal core overlayed with porcelain. These types of crowns will often have a metal margin that presents as a dark gray or black line. When they are first placed in the mouth the dentist will usually hide the margin by placing it slightly beneath the gum tissue. As the tissue receeds then the dark margin becomes exposed and thus you see a "black" line. The other type of crown is an all porcelain crown which has no metal at all. There are many variations of all porcelain crowns but they will eliminate the dark gray margin that you often see with porcelain fused to metal crowns. A talented lab technician and skilled dentist can make beautiful crowns whether they use a PFM or an all porcelain. The lab/dentist team will often discuss the esthetic goals of the case to determine the best choice of material.
Kamini Talati (Port Saint Lucie, FL) on Aug 29, 2011
If the crown is porcelain fused to metal then the black line you see is the metal margin. There is nothing you can do to change that. Get a new crown that is metal-free.
Leonard Tau (Philadelphia, PA) on Aug 29, 2011
The black at the top of a crown is typically the metal under the porcelain. It could also be a dark root, if the tooth has a root canal. The only way to get rid of it is to have an all-porcelain crown placed on the tooth.
Carolyn Van Buskirk (New York, NY) on Aug 29, 2011
No, crowns are not supposed to turn black at the gumline, and if treatment is planned and coordinated properly this should not happen. We have several aesthetic and strong porcelain materials available that allow us to make all-porcelain crowns that do not have a metal core or understructure that can show through at the gumline area. Sometimes where porcelain-metal crowns are recommended instead of all porcelain crowns, as in cases where the patient grinds his or her teeth, a porcelain-gold crown can be the ideal type of crown to use. Also, before starting work on a crown, the gums should be evaluated. In some cases the gum needs to be "augmented" with a connective tissue graft to prevent further recession, (areas with recession can appear darker than the crown) and to provide the proper "frame" for a crown. Unfortunately, if a crown appears dark or black at the gumline, this "blackness" can not be removed, and can only be corrected with a new crown. Patients should be sure their dentist performs a thorough exam before starting a crown, and should ask to see before and after pictures showing the doctor's work. In my office I offer complimentary consultations where new patients can review photo albums of my work, and I can make recommendations for the optimal treatment approach.
Les Latner (Los Angeles, CA) on Aug 29, 2011
Crowns that have metal or gold underneath the porcelain may show a black line at the margin (the line where the crown ends and the tooth continues under the gums). Usually this is covered by the gums when the crown is initially placed, but over time, the gums may recede and expose this margin. The black cannot be removed. The only way to remove the black is to replace the crown. With today's techniques, in many cases, an all-porcelain crown can be used and this black line will not appear.
Inna Shimanovsky (Oregon City, OR) on Aug 29, 2011
Crowns do not supposed to turn dark if they are made out of porcelain. If it is a composite crown it may get stained and it that case it would need to be repolished.
Brian Gray (Washington, DC) on Aug 29, 2011
Hi. Crowns turn dark at the margin (top) usually due to receding gums. The dark color is generally attributed to the metal substructure located at the cervical margin (edge) of the crown. It also can be due to a dark root surface that is exposed. The root can often turn dark associated with the nerve "dying" - in need of or after a root canal treatment. You generally cannot polish off the dark area. This dark area is often addressed nowadays via all-ceramic crowns. These non-metallic crowns blend better with the root and do not have any dark material.