Black Lines at the Base of Your Dental Crowns?

Do you have an old dental crown? If so, you could have noticed a thin black line near the gum line. Is that dark gumline decay? Plaque? Tartar? Before you worry that your tooth may be in danger, continue reading to learn what this dark line is, and how to remove it for a more aesthetic smile.

If you are unhappy with a dental crown that doesn’t match your natural smile, Lake Forest Dental Arts can help. As one of Chicago’s top cosmetic dentists, Dr. Fondriest helps patients from all over the greater Chicago area, and across the country, create a smile they love. We offer unique “artistic smile design” which crafts smiles not just for function, but aesthetics. If you’d like more information, or would like to schedule a cosmetic consultation, call us at 847-234-0517.

Types of Dental Crowns

First, let’s discuss the types of dental crowns that are available. Depending on the dentist, the location of the crowned tooth, and the other issues surrounding the restorative process, your dental crown could be fabricated from any one of these materials:

Metal: metal crowns are usually immediately obvious, as they are fabricated from gold, nickel, or other metals and metallic alloys, appearing in stark contrast to the natural color of your teeth. While metal crowns are not very aesthetically pleasing, they are incredibly durable and long-lasting — they very rarely break or chip.

Porcelain-Fused-to-Metal: using the strength of metal with the aesthetics of porcelain, porcelain-fused-to-metal crowns are a popular alternative to metal crowns. However, the porcelain exterior is more prone to chips or breaks than an all-metal crown.

Ceramic or Porcelain: the most natural-looking option, and a good choice for highly-visible teeth, porcelain and/or ceramic crowns very closely mimic the coloring and appearance of natural, glossy white enamel. However, depending on how they are made may be less durable and must be replaced more frequently than metal based crowns.

Resin: resin crowns are usually only used as a temporary cap for a tooth that has recently undergone restoration. Resin caps are temporarily placed until a final crown, created with one of the above materials, is complete. Resin crowns are extremely susceptible to breaks, cracks, or chips, but can be colored to closely match a natural tooth color.

black line at gumline

A black line will form on a crown when a crown leaks at the margin. This black line can also occur in a low quality crown when the underlying metal isn’t concealed.

The Thin Black Line | Dark Gumline

Surprisingly, the thin black line is actually a part of your dental crown. Porcelain-fused-to-metal (PFM) crowns have long been a standard in cosmetic dentistry. Before all-ceramic and zirconia crowns were available, PFM crowns were the only alternative to a very obvious metal crown. On front teeth, metal crowns stand out, so dentists found a solution for helping the crown blend in with the rest of the smile; thus, the porcelain-fused-to-metal crown was born. Over time, as gums recede from a result of aging, periodontal disease, or aggressive brushing, a dark or black line is revealed at the base of the crowned tooth, right on the gum line. When the dark line develops, the previously “seamless” look of your PFM crown is gone.

Good or Bad: Porcelain-Fused-to-Metal Crowns

Today, some patients have heard that PFM crowns are not good for their teeth. Many patients will ask whether they should have them removed and replaced with a non-metal porcelain crown. The short answer, is not necessarily: PFM crowns are not bad for your health. Aside from their possible aesthetic issues, if a porcelain-fused-to-metal crown is strong, comfortable and properly functioning, it does not need to be removed. And while some PFM crowns will display a thin black line, others that have what is called a porcelain “margin” do not reveal metal even after gum recession occurs. This is because special precautions were made when fabricating the crown, to ensure that the black line never develops (and is the sign of a well-made PFM crown).

For some patients with metal-margined PFM crowns in the back of their mouth, a visible thin black line may not be bothersome; for the most part, the thin black line may be indistinguishable when speaking or eating. However, for patients who received a PFM crown for a front tooth and now have a highly visible black line, replacing a PFM crown with a newer, higher-quality PFM crown or an all-porcelain crown can help achieve the more natural-looking restoration. By replacing old or poorly made PFM crowns, you can hide any evidence that your crown isn’t natural enamel.

Not All Crowns are Made Equal

The truth is, the quality of your PFM crown depends on how it’s made. Dentists pay from $35 to $155 for a PFM crown from the dental lab. For just $60 more, the crown can have a porcelain butt-joint-margin, which means, if your gums recede, a metal margin (that black line) won’t be revealed. Instead, the tooth will look completely white. This black line can also occur in a low quality crown when the underlying metal isn’t properly concealed with porcelain.

Another consideration is the metal material used. An inexpensive alloy will not cast well (part of the fabrication process), so the crown won’t fit as well as it would if a better metal were used. Also, biocompatibility (the body accepting the crown material) may be a problem. With inexpensive crowns, the ceramic baked over the metal may be more opaque – less natural looking. Your best option is a 14+ karat gold crown under veneering ceramic, with a butt-joint-margin. With a full gold underlay, your receiving tooth will require less preparation, as well.

On the other hand, all-porcelain crowns are often the most natural-looking option for front teeth. The porcelain material can resemble enamel much more closely than PFM crowns. Sometimes, a PFM crown can appear flat or stark white, because of the dense, dark-colored metal underneath the porcelain. If you are concerned about the aesthetics of your smile, and not only want to remove an unsightly black line but also improve the overall look, tone, and color of your crown, porcelain could be the best option.

Contact Lake Forest Dental Arts

If you have developed a thin black line on a crowned tooth, especially one that is near the front of your smile, Dr. James Fondriest can help! Call Lake Forest Dental Arts to schedule a consultation with Dr. Fondriest and discover your options for attaining a more natural-looking dental crown.

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