<unk> , also known as the<unk>  line or<unk> ian line, is a clinical sign found in patients with chronic lead poisoning. It is a very thin, black-blue line visible along the margin of the gums, at the base of the teeth. The sign was described in 1840 by Henry<unk> : A similar line, the "bismuth line", occurs in people who have ingested bismuth compounds; bismuth, however, is of very low toxicity.
Burton's line
Blumensaat's line
Schwalbe's line
Hampton's line
Hilgenreiner's line
Beau's lines
Klein's line
McBurney's point