<unk>  usually occurs on the mandibular gingiva, often in an area in which an apicoectomy ("root-end filling") with<unk>  was carried out. After the gingiva, the alveolar mucosa and the buccal mucosa are the next most common sites, although any mucosal site in the mouth is possible. It is painless, and appears as a blue-black or grey discolored macule on the surface of the mucosa. The borders of the tattoo are variable, and may be well defined, irregular or diffuse.
Amalgam tattoo
Soot tattoo
Debulking
Circumcision
Cigarette burns
Tincture of benzoin
Scorpion sting
Indoor tanning