ohaguro

thumb|Teeth blackening. by Kunisada|Utagawa Kunisada, 1820, from the series Mirrors of the modern boudoir.

is the name given in Japan to the custom of blackening one's teeth with a solution of iron filings and vinegar. It was especially popular between the Heian and Edo periods, from the 10th century until the late 19th century, but the opening of the country to Western customs during the Meiji period led to its gradual disappearance. It was a tradition practiced mainly by married women and some men, almost always members of the aristocracy and samurai. In addition to Japanese society's preference for black teeth, it was also considered beneficial to health, as it prevented tooth decay by acting as a dental sealant. The practice of dyeing one's teeth black was also a known and widespread practice in southeastern China and Southeast Asia, although with different recipes.