Ohaguro

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.

[4] Due to a phonological process called rendaku, the "k" in kuro voices to become a "g" sound, and the compound term is pronounced ohaguro, not *ohakuro.

The reasons for the invention of ohaguro are still unclear:[1] simple dental care has been proposed, as well as the differentiation between humans and demons depicted with large white fangs,[8] just as in other Southeast Asian cultures; the fact that teeth are the only visible part of the skeleton, which links them to death and makes them taboo;[9] or the Japanese and other Far Eastern cultures holding a preference for concealing the public display of feelings with the combination of oshiroi (white makeup), the complete plucking of the eyebrows, and their repainting – a practice known as hikimayu (引眉, hikimayu) – and the dyeing of teeth creating a masklike appearance.

[b] When a samurai dyed his teeth black, it reflected his decision not to serve another lord for the rest of his life,[12] and, from the time of the shikken or regents of the shōgun, the nobles applied it with similar regard for loyalty.

[17] In the particular case of samurai and members of the nobility of these periods it was customary to dye their teeth for the first time upon passing their genpuku or initiation ceremony, at the age of fifteen or sixteen.

[7] In the celebration of marriages, those relatives of the bride who were responsible for assisting her in the process and introducing her to others were given the name kaneoya (鉄漿親) or kanetsuke-oya, literally "godmother" of kanetsuke (blackening of teeth).

[25] In 1870 the government banned the practice of ohaguro on men,[26] and the tradition gradually became obsolete, especially from 1873 among married and noblewomen, when the Empress Shōken decided to appear in public with white teeth.

[30][32][33] Alcock surmised that its purpose would be chastity by intentionally making women unattractive,[30] which would prevent potential extramarital affairs[34] and his view of this custom hardly changed during his three-year stay in Japan:[d] Once they have renewed the black varnish on their teeth and plucked every last hair from their eyebrows, Japanese married women could assert their unparalleled preeminence in artificial ugliness over the rest of their sex.

[36] Bertram Freeman-Mitford transcribed in his Tales of Ancient Japan a recipe which he claimed had been described to him by a reputable apothecary in Yedo: Take three pints of water and, having heated it, add half a cup of wine (sake).

Then the teeth are painted with the liquid by means of a soft feather brush with more iron and gall powder and after a few applications, the desired color will be obtained.

In kabuki theatrical performances, actors painted their teeth black whenever they played married women, courtesans, and with some noblemen,[38] for which they traditionally used a mixture of brown sugar and pine resin.

[39] The mixture used in kabuki was given the name hayagane,[38] and in more complex formulations could include wax, pine resin, carbon black, red pigment, rice honey, and lamp oil, all softened over a flame.

[2] In China there has been knowledge of the custom of teeth blackening throughout history, although it was not practiced in the domains of the Middle Kingdom, nor did the majority of its ethnic groups.

[6] As early as the 4th century BC's Shan Hai Jing, the description of a 'black-toothed country' or Hei-chi-guo (黒歯国) appears, which some associate with Japan itself[3] and most others with the Southeast Asian area due to its extent in the region and greater antiquity.

[10] It was also a demonstration of civilization, as there was an idea that white teeth belonged to animals, savages, and evil spirits,[10] especially because of the presence of large protruding canines in all of them.