Why Does My Crown Have a Gray Line at the Gum Line?

Why is there a gray line at the edge of my dental crown? Why does the tooth that has a crown not look natural in photographs? These are questions that patients ask from time to time. These types of questions come from patients that have received porcelain fused to metal crowns, also known as a PFM crown.

Porcelain fused to metal crowns have been a standard in dentistry for a very long time. When done well, they can look great and last a very long time. It is a quality dental restoration for sure. In the last several years, though, the technology for all ceramic and zirconia crowns has improved dramatically. The strength, esthetics, and durability has gotten to the point where they are superior to porcelain fused to metal crowns in almost every way. Patients and dentists alike are satisfied with the look and fit of the crowns.

One of the great things about the zirconia crowns and all ceramic crowns is there is no dark metal substructure. The crown is white like a tooth through and through. When you look at the crown in your mouth, it looks like a tooth. Some patients experience recession in their gums as they age. If the gums recede around a ceramic or zirconia crown, or if toothbrush abrasion wears some of the porcelain away at the gum line, there is no danger of a gray line appearing at the gum line because there is no metal in the crown.

The no metal substructure thing solves another problem: photographs. When you see a tooth with a PFM crown in a photo, typically the light isn’t very forgiving and it appears unnatural. With the ceramic and zirconia crowns, light bounces off them in a much more natural way, and they appear like real teeth.

Porcelain fused to metal crowns are still great, but they will likely not be a part of the future in dentistry as more and more dentists become familiar with the materials and techniques involved in the world of zirconia and ceramic all-white crowns. Personally, I haven’t made one for a patient in several years, but they still have a place in dentistry. Depending on the clinical situation, I typically choose an IPS e.max (porcelain) or Bruxzir (zirconia) crown. If you have a crown in an esthetic area that has a metal margin showing that bothers you, talk to your dentist about your treatment options. There are many options to make your smile look the best that it can be!

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