Pigmentation in the oral cavity can result from numerous causes (Table). Thus, a careful history is important. Ask the patient about occupational exposures, medications ingested, and familial disorders. Intrinsic substances deposited include melanin, which is the most common, and hemosiderin; extrinsic material consists primarily of heavy metals, such as lead, mercury, bismuth, and silver.
In all persons except albinos, the basal layer of the oral epithelium normally contains melanocytes. Among African-Americans and others who are dark-skinned, areas of increased pigmentation may not be abnormal.