Mercury sensitisation: review, relevance and a clinical report.

Eczematous eruptions may be produced through topical contact with mercury and by systemic absorption in mercury sensitive individuals. Mercury is considered a weak sensitiser and contact with mercury salts such as chloride or ammonium chloride may cause hypersensitivity leading to contact dermatitis or Coomb's Type IV hypersensitivity reactions. The typical manifestation is an urticarial or erythematous rash, and pruritus on the face and flexural aspects of limbs, followed by progression to dermatitis. True allergy to mercury is rare but is more common in females. Exposure to mercury vapour produced in operating rooms is the main concern for dentists. Every effort should be made to avoid contact with mercury vapour if possible by using barrier techniques, reducing the temperature of the operating room and of the amalgam restoration. Air conditioning and proper ventilation of the operating room, the use of coolant sprays, good suction and proper handling of amalgam waste is recommended. Various reports show the use of MELISA (memory lymphocyte immunostimulation assay) and patch tests in determining mercury sensitivity. Topical application of glucocorticoids and dimethisone is helpful.