Ohaguro
Ohaguro (Japanese: お歯黒; pronounced [ohaɡɯɾo], lit. 'black teeth') 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.