It almost looks like you might have black gums above your crown. But the hygienist says that you have healthy gums and certainly no gum disease. So if your oral health is good, then what could that darkness at the gumline be? Are your crowns older than 9 years? If so, you may have noticed a thin black line at base of the crown?
Is that darkness at the gumline decay or an amalgam tattoo? Plaque? Tartar? Before you worry that you have a medical condition such as oral cancer, continue reading to learn what this dark line is.
The Thin Black Line at the base of a crown | Darkness at Gumline
That darkness at the gumline is not unhealthy tissue. 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, Porcelain-on-metal crowns were the only alternative to a very obvious metal crown.
On front teeth, metal crowns would stand out. Dentists eventually found a solution for helping a crown to blend in with the rest of the smile. This is how the porcelain-fused-to-metal crown was born. Unfortunately over time, the gum tissues will recede from a result of aging, periodontal disease, or aggressive brushing. Eventually 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.
Not all crowns are made equal and many have darkness at the gumline
The truth is, the quality of your PFM crown depends on how it’s made. Dentists pay a ceramist from $35 to $1700 to make a PFM crown. For just $60 more, the crown can have a porcelain butt joint margin to conceal the metal base. If your gums recede, no metal (that black line) will be revealed. Instead, the tooth will look completely white. If your crown is supported by a dental implant, the metal abutment may become exposed.
This darkness at the gumline is more likely to occur with a low quality crown. With cheaper versions, the underlying metal isn’t properly concealed with porcelain. If a world class technician creates your crown, it will be difficult to tell it isn’t real.
Sensitivity to some types of metal used in your restorative dentistry
Another consideration is the metal material used. An inexpensive alloy will not cast as well (part of the fabrication process). A poorly fitted crown won’t fit as well as it would if a better precious metal were used. Also, biocompatibility may be a problem. If the body reacts negatively to the non-precious metal alloy, it could cause receding gums.
With inexpensive crowns, the ceramic baked over the metal may be more opaque and 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, The crown will fit better and match better. If you get the butt joint margin, it is less likely to have a darkness at the gumline.
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.
It is normal to be concerned about the aesthetics of your smile. Do you want to get rid of the darkness at the gumline? If you want to improve the overall look of your old crown, a porcelain only cap could be the best option.
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.
If a porcelain-fused-to-metal crown is strong, comfortable and properly functioning, it does not need to be removed. While some cheaper or significantly older PFM crowns will display a darkness at the gumline, others will not. If it has what is called a porcelain “margin”, it will not reveal metal even after gum recession occurs. This is because special precautions were made when making the better version crown, to ensure that the black line never develops.
For some patients an exposed metal margin in the back of the mouth may not be bothersome. The thin black line may be indistinguishable when speaking or eating. However, if this is present on a front tooth, most will look for a crown replacement. A new higher quality PFM or a new porcelain crown. By replacing old or poorly made PFM crowns, you can hide any evidence that your crown isn’t natural enamel.
Does poor oral hygiene cause darkness at the gumline?
Poor oral hygiene can cause the appearance of a dark gum. Inflamed and bleeding gums have a deep red appearance and can visually appear as dark spots. Certainly unhealthy gums can lead to the loss of a natural tooth. Brushing your teeth and gums is highly recommended.
Learn more about fixing the black line at the base of your crown
Have you have developed a thin black line at the base of a crown? Especially one that is near the front of your smile. Would you like to replace your old dentistry with life-like crowns?
Dr Fondriest is a nationally recognized and highly sought after cosmetic dentist. He serves clients from throughout the United States