Patients often ask us, “Doc, what’s this black line around my dental crown? Is it dirt?” The black line isn’t a sign of dirt or age, but it could mean three things: receding gums, the material of the crown or crown fit problems. Let’s explore these causes in greater detail.
Receding gums are a condition where your gums pull back from the tooth surface, exposing the root surface of your tooth and causing your tooth to look long. It is a form of gum disease and is often caused by poor oral hygiene, vigorous tooth brushing, teeth grinding or shifting teeth. If you have receding gums, you may experience sensitivity to hot and cold food and notice some space between your teeth.
If your gums start to recede when you have a dental crown on, that black line may actually be a part of your natural tooth structure, especially if you’ve had a root canal or traumatic injury prior. Please note that regardless of material, all dental crowns are susceptible to receding gums, so it’s important to practice good oral hygiene and visit your dentist regularly even with a crown on.
Material of the crown
This is actually one of the most common reasons behind a black line around a dental crown. Prior to mainstream use of porcelain crowns, dental crowns were commonly made of porcelain fused to metal. This means that the crown is made of a metal base with a porcelain cover. The black line is the junction where the tooth and crown meet — if this margin occurs near the gum line, then a dark line shows.
In the past, porcelain fused to metal crowns were the standard for crowns due to their strength and natural appearance. Today, all porcelain crowns and ceramic crowns can provide the same support and aesthetics minus the risk of the black line. At Dental Designs, we use metal-free dental crowns made entirely of modern ceramic materials. This allows us to conserve more tooth volume as well.
Porcelain crowns are typically more expensive than porcelain fused to metal crowns, but they produce better results and are worth the investment in the long run.
Crown fit problems
You can limit or stop tooth decay and gum recession with good oral hygiene — but if your crown doesn’t fit properly in the first place, all your efforts might go to waste. When a crown is not placed properly, it can make cleaning very difficult. Over time, this lack of proper cleaning can lead to tooth decay, gum disease and subsequently gum recession.
Yes, although a crown protects natural tooth structure, decay is still possible without adequate oral hygiene. To prevent a poorly fitted crown, pick a dentist who has a good track record with dental restorations and schedule regular dental checkups.
How do I get rid of the black line around my crown?
The only way to get rid of the black line around your crown is to replace your crown entirely. The good news is that it is not a difficult process and takes just a few hours of your time.
Here’s how it’s done:
- Your dentist will make a slit through your crown (just to the point of tooth contact) and pop the crown off using a special tool. This breaks the bonding seal and removes the crown without damaging your underlying tooth.
- A new impression of your teeth is taken to create your new crown. With us, this process includes using a 3D CEREC scanner to create a 3D model of your teeth, using the CEREC software to create the shape of your new crown, milling your crown in our in-house lab and finally hand painting it so it looks realistic. Everything is done on the same day.
- You might experience some gum tenderness and soreness after the procedure, but this is normal and should resolve in 2 weeks.
Many patients find that with their new crown, they look a lot younger and healthier. Your teeth play a huge role in your smile and appearance; if you don’t like the way your crowns look or are looking for a smile makeover, we can help!
- Chowdhuri, M. A., Xia, Z., & Yu, D. (2011). A study on optimal bonding angles of bi-material interfaces in dental crowns with porcelain fused to metal. Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine, 225(7), 657–668. https://doi.org/10.1177/0954411911401781
- Bluma, E., Vidzis, A., & Zigurs, G. (2016). The influence of fixed prostheses on periodontal health. Stomatologija, 18(4), 112–121.