Black hairy tongue.

Black hairy tongue is a benign disorder characterized by hypertrophy of the filiform papillae of the tongue. A brownish-black discoloration of the papillae occurs. The etiology is unclear, but the disorder has been associated with numerous predisposing conditions. Although black hairy tongue is usually cured by removal of these factors, a variety of measures, particularly brushing of the tongue, may aid in resolution.