Why Do Dental Crown Edges Turn Black? And How to Fix It

Why Do Crown Edges Turn Black?

If the edge of your dental crown turns black, it’s usually because your gums have receded or the metal in the crown has leaked and stained the area. Receding gums are a serious oral health issue that needs to be fixed right away; staining from metal is just a cosmetic problem and can be handled depending on how bad it is.

Receding gums: When gums recede, they pull back from the crown, exposing the metal inside porcelain-fused-to-metal (PFM) crowns—that’s what makes the edge look black. Gums recede because of gum disease, incorrect brushing habits, or if you were born with naturally thin gums.

Wrong crown material: If your crown is made of a material that doesn’t work well with your body (poor biocompatibility), it can irritate your gums and surrounding tissues. This can lead to allergies, corrosion, and metal leakage, which may cause gum inflammation, bad breath, and those unsightly black lines along the gum line.

Cheaper PFM crowns are very common in China because they’re affordable. But they have downsides: they don’t fit as well around the gums, and they don’t work well with the body. After wearing them for a while, some people get black lines on their gums, and some even have allergic reactions.

Most PFM crowns start having problems after 3 to 5 years—like chipped porcelain, weird color, falling off, weak chewing, bleeding gums, or gum disease. Blackened edges are one of the most common issues, and it’s best to get them fixed quickly to avoid more damage.

What to Do in an Emergency？

1. Save the tooth root

If your crowned tooth is loose or painful/inflamed, go to the dentist right away for an X-ray to check if the root is healthy.

2. Get rid of black lines and stop gums from receding

The most important thing about a good crown is how well it fits your gums. If it doesn’t fit tightly, bacteria can get inside, causing inflammation, receding gums, and blackening.

3. Replace the crown material

Choose a mid-range to higher-priced crown that’s safe and works well with your body. All-ceramic or bionic crowns are good options—they’re less likely to cause problems.

4. Take care of your gums

If your crown has failed, your gums are probably unhealthy too. The dentist will first treat your gums to make sure your mouth is healthy before doing anything else.