Dark Line at the Gumline | Cosmetic Dentistry

Question:

I am told that dental crowns, including Procera and IPS Empress used on front teeth will eventually develop a dark line near the gumline. Is this true?

—Gloria from Connecticut

Gloria,

Porcelain fused to metal crowns especially will eventually have a dark line at the gumline. It can even be a black line. This is from the metal showing through. Procera crowns can also develop a dark line, but it isn’t as noticeable, because there is no metal in a Procera crown. Empress crowns won’t, because they are bonded, and because the material is translucent. Empress can be done so that it blends nicely into the tooth with an invisible margin.See the pictures on the right to have this illustrated. The top picture shows two porcelain fused to metal crowns on a patient’s lateral incisors. There is a prominent dark line, even a black line, at the gumline. It is very noticeable and is in stark contrast to the white opaquer that shows just below that line, at the base of these crowns.

Another example of dark line at gum line

On the lower picture, those crowns have been replaced with all-porcelain crowns, as part of a complete smile makeover that this woman had. There is no more dark line at the gumline.

With porcelain fused to metal, the line is black, very noticeable and ugly. Often, laboratory technicians will cut back the metal at the gumline. This makes the line less noticeable, but because of the opaquer that has to still be used, it is very difficult to get the invisible color transition that is fairly easy to get with bonded porcelain. With Procera, depending on how it is done, it may be more like a dark line, maybe a gray line, and it will be more subtle—it won’t be so noticeable.

For a porcelain crown on a front tooth, I recommend an all-porcelain crown such as feldspathic porcelain or Empress, or the newer all-ceramic crowns such as zirconia or e.max crowns.

Dentists who are serious about cosmetic dentistry will have a strong aversion to doing porcelain fused to metal crowns on front teeth. My advice, though, if you’re concerned about the possibility of this dark line at the gumline, is not to ask your dentist to do an all-porcelain crown unless you are offered that as one of your choices. Dentists who know how to do these more esthetic crowns will strongly prefer them, and if you are not given that as an option, it’s an indication that your dentist doesn’t know how to do them well. If it’s important to you, look for a dentist on our referral list who knows how to do these. That’s the best way to avoid the dark line at the gumline.

—Dr. David Hall

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