Burton's line in lead poisoning.

Lead poisoning in both its acute and chronic forms has been recognised since the second century BCE. Lead colic, anaemia, renal tubulopathies and motor neuropathies are well recognised. This paper sketches the early history and remembers the important contribution of Henry Burton, who described the gums to be bordered by a narrow leaden-blue line, about the one-twentieth part of an inch in width, whilst the substance of the gum apparently retained its ordinary colour and condition. The sign though inconstant, is still a valuable clinical clue.