What is "amalgam tattoo"

n. A flat, bluish-gray lesion of the oral mucosa that results from amalgam particles going into the soft tissue.

Amalgam tattoo (also termed localized argyrosis, or focal argyrosis) is a grey, blue or black area of discoloration on the mucous membranes of the mouth, typically on the gums of the lower jaw. It is an iatrogenic lesion, caused by entry of dental amalgam into the soft tissues. It is common, painless, and benign, but it can be mistaken for melanoma.