Dark gums and a black line around a crown: causes and solutions
One of the most common complaints with crowns made years ago is a grey-black line where the crown meets the gum, or gum that looks purple-grey. Usually it's the metal framework of a metal-ceramic crown showing at the edge, or being exposed as the gum recedes. A darkened root in a root-filled tooth, gum inflammation and metal stains left from old amalgam fillings can look similar. Depending on the cause, gum treatment, replacing the crown with a metal-free one or gum aesthetic procedures may be needed.
Causes of the black line and dark gums
| Cause | What it looks like |
|---|---|
| Metal-ceramic crown | A thin grey-black line at the crown edge; light can't pass through metal, so the gum looks shadowed |
| Gum recession | The crown edge and root surface that were under the gum become visible |
| Darkened root | The root of a root-filled or dead tooth shows dark through thin gum |
| Metal post | Metal inside the root gives thin gum a grey shadow |
| Gum inflammation | Red, purple, bleeding gum at an ill-fitting crown edge |
| Amalgam tattoo | A permanent, flat, blue-grey patch on the gum (metal particles from old fillings or root canal work) |
Natural pigmentation of the gum and brown patches in smokers also occur; these have nothing to do with the crown. See smoking and your gums.
Gum health first
If a crown edge overhangs, has a gap or is rough, plaque builds up and the gum becomes inflamed: red, purple, swollen and bleeding. This spoils the appearance and sets the stage for decay under the crown. The inflammation is treated first with gum treatment; then we look at whether the crown needs replacing. See gum treatment, pain and odour under a crown.
Solutions
- Replacing with a metal-free crown: Zirconia or all-ceramic crowns let light through, so there's no metal line at the edge. See zirconia or porcelain, types of dental crowns.
- Masking a darkened root: An opaque framework, internal whitening of the root, or a fibre post instead of a metal one.
- Gum graft: To thicken thin gum and cover a receded area. See gum grafts.
- Correct placement of the crown edge: The new crown's margin is planned so it doesn't harm the gum.
- Amalgam tattoo: Harmless; if needed for appearance, it can be corrected with a minor surgical procedure or a graft.
What to watch for when a crown is replaced
- Once the old crown is off, the tooth and root are checked for decay and the root canal filling is assessed.
- A temporary crown may be worn for a while to let the gum heal.
- The shade is chosen with the neighbouring teeth, in daylight.
- The new crown's fit at the edge and its contacts are checked. See sensitivity after a crown.
For how long zirconia crowns last, see how long zirconia crowns last.
Assessment in Beylikdüzü
At Dent32 we find the cause of darkening at a crown edge with an examination and X-ray, and explain the options — gum treatment, a new crown or gum aesthetics — in writing. For zirconia crowns in Beylikdüzü, see zirconia crowns.
Dent32 Ağız ve Diş Sağlığı Polikliniği (Dent32 Dental Polyclinic) is at Barış Mah., Ginza Lavinya, E-5 Yanyolu No:30 D:179, 34520 Beylikdüzü, Istanbul and is open seven days a week. To book, call or WhatsApp +90 555 011 33 68, or use our contact page. At the examination we share the findings, the options and the approximate cost in writing; you are under no obligation to start treatment afterwards.
For clinic details, our dentists and the full list of treatments, visit Dent32, dental clinic in Beylikdüzü.
Frequently asked questions
What causes the black line at the base of a crown?
Most often it's the metal edge of a metal-ceramic crown showing, or exposed as the gum recedes. A darkened root and gum inflammation can look similar.
Will dark gums go away?
If the cause is gum inflammation, it improves with treatment. If it's metal or a darkened root, it won't go away unless the crown is replaced with a metal-free one or the root is masked.
Can zirconia crowns show a black line?
Zirconia has no metal framework, so there's no metal line. However, if the gum recedes the root surface can show, or a darkened root can cast a shadow through thin gum.
