Pigmentation by exogenous deposit

Many drugs or molecules (including amiodarone, ketoconazolo, tetracycline and chlorhexidine) have been associated with the presence of pigmented lesion in the oral cavity. From a pathogenetic point of view, the mechanisms by which this lesion can co-exist varies: 1) a direct depositing on the oral surface; 2) a peripheral accumulation after systemic absorption; 3) by stimulating the metabolic processes which lead to an increase in the production and depositing of melanin or catabolic bacteria. With the aim of excluding malignant pathologies, a pigmented lesion necessitates biopsy and histopathological examination. Pigmentation can involve the tongue highlighting the clinical features of black hairy tongue. Black hairy tongue is a developmental change to the upper side of the tongue where a thick, blackish coating (patch or plaque) presents with hypertrophic filiform papillae, which are lengthened in appearance. The coating can be removed, being composed of bacterial cells, exfoliated epithelial cells and residual food products. Colouration is due to the production of dark pigments by various species of bacteria or the consumption of tobacco, or the use of various products containing chlorhexidine (e.g. mouthwash), or an imbalance in the oral ecosystem, the latter which is secondary to prolonged antibiotic use. Black hairy tongue is not a pathological condition but it can be associated with marked halitosis. When there is a burning symptomatology (not always present) a swab is useful to ascertain the presence of a fungal superinfection (the examination should be made at least 7 days after the mouthwash or related product is no longer used). And this is in addition to effective tongue hygiene, the cessation of smoking and use of colouring agents.