Black teeth were a sign of social status in Japan long ago, particularly among women. This practice, known as ohaguro, involved staining the teeth black, often using a mixture of iron filings, vinegar, and tannin-rich plant sources. Ohaguro was primarily seen as a symbol of beauty, maturity, and elegance, especially among aristocratic women and samurai wives. It also had practical benefits, as it protected the teeth from decay.

The practice dates back to at least the Heian period (794–1185) and continued in various forms until the late 19th century. When Japan opened to the West and modernization began, ohaguro fell out of favor, and white teeth became the new aesthetic standard.