Why Are Black Lines Forming Around My Dental Crowns?

You’ve just finished brushing, and you pause to admire your smile in the bathroom mirror. Your teeth are white and resplendent, and your gums are vibrantly pink—but a dental crown covering one of your molars catches your attention. Something seems off, and upon further inspection, you notice that a thin black line has formed around the bottom of your crown. You check your other crowns and notice the same imperfection. You have no earthly idea what these lines are or why they’re there, and you begin to feel a little anxious. But there’s nothing to worry about; here’s what’s going on.

What Exactly Are These Black Lines?

Although it might seem like someone has taken a pen and outlined the bottom of your crown, this is not the case. These black lines are usually caused by one of two things: the metal from an existing crown becoming visible, or in rarer cases, the crown itself casting a shadow onto the tooth.

Older dental crowns contain porcelain that is fused to a layer of metal, usually gold alloy (they’re called PFM crowns). The metal provides a framework for the delicate porcelain and is hidden under the gum line when the crown is fitted. But as you age, your gum line gradually recedes, and this metal part eventually becomes exposed and appears as a dark line.

Sometimes the black is merely an optical illusion created by a poorly fitted dental crown casting a shadow over the surrounding area. However, these lines are often less prominent than the ones caused by the exposed metal of a crown.

What Should I Do About Them?

If you want to get rid of those unattractive dark lines, you will need to replace your existing PFM crowns with modern ones made of zirconium oxide or porcelain. These newer crowns do not require any metal framework, and they’ll fit better than the originals—meaning there’s no different material which can become exposed and no room for a shadow to be cast.

It is important to maintain good oral hygiene, especially if you’ve received dental crowns—keeping gum recession at bay will help to ensure your crowns continue to look natural for many years to come. Keeping your mouth clean will also help to prevent decay from forming around the edges.

It might be alarming to open your mouth and see black lines forming around your dental crowns; they are supposed to be helping your smile, not hurting it! However, it’s ultimately a minor issue that can easily be corrected by visiting your dentist.

About the Practice

Edgewood Dental proudly serves families in the Michigan City Community and is led by the elite trio of Dr. Valerie Haughtington, Dr. Vidas Noreika, and Dr. Caleb Havlin. They strive to offer the best available care in preventive, restorative, and cosmetic dentistry, and are committed to providing a positive and informative experience for all their patients. If you have any questions about dental crowns or would like to contact one of the doctors at Edgewood Dental, they can be reached via their website or (219) 898-4545.