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Mouth Diseases

Dark Spot Under Tongue



I have a large black spot on the bottom of my mouth. What type of doctor should I see? What would cause this?


The most common reason for a black spot under the tongue is the result of having an old silver filling (amalgam) removed or replaced from one of your nearby teeth or having a tooth with a big silver filling prepared for a crown. The dentist's hand piece (AKA the drill) can throw off small pieces of the filling at such a high speed that they pass right through the thin skin under the tongue and lodge in the underlying connective tissue. The end result is a form of tattoo (amalgam tattoo). They are harmless and require no treatment. It is possible that this has been present for some time before you noticed it.

Unfortunately, very rarely a dark spot in the mouth can be caused by a form of cancer known as oral melanoma. This serious disease is usually seen on the skin and the rare mouth (intraoral) cases typically occur on the roof of the mouth (hard palate) or on the gums (gingiva). However, it is possible for them to occur anywhere in the mouth.

To be safe, you should see your dentist or a dental specialist such as an oral surgeon or an oral pathologist. If there is any question about the diagnosis, a biopsy of the dark spot may be recommended so you and your doctor will know if any other treatment is needed. Good luck!

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Response by:

John R Kalmar, DMD, PhD John R Kalmar, DMD, PhD
Clinical Professor of Pathology
College of Dentistry
The Ohio State University