Dermatol Online J. Oct 16;21(10). pii: /qt0z57p9xr. Graphite oral tattoo: case report. Moraes RM(1), Gouvêa Lima Gde M, Guilhermino M, Vieira MS. 6 Aug Oral tattoos and piercings seem cool, but can they actually affect your dental and overall health? Read on!. Amalgam tattoo 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.