Teeth beleefs [sic]

In Western folklore, the Tooth Fairy is a gentle, magical being who rewards children (usually with money) for losing their baby teeth. This encourages children not to be afraid of losing teeth, and serves as a rite of passage, marking the child's growth.

Japan has its own unique traditions for baby teeth, but they don’t involve mythical beings.

It goes like this:

  • If a lower tooth falls out, the child throws it onto the roof.
  • If an upper tooth falls out, they throw it under the floor.
  • While doing this, they often say something like: "May the upper teeth grow straight to the ground and the lower teeth to the roof." In other words, may their teeth grow vertically, and not stick out or be crooked.

Then when they get older (particularly girls) a recent fad has been to change their teeth to appear much younger than they are. In the West, such 'snaggleteeth' (八重歯, yaeba) would be something to rectify, but in Japan, yaeba is considered cute.

Another canine superstition relates to dreaming about teeth falling out. According to a survey reported by Nippon TV, dreams of teeth falling out (歯が抜ける夢 ha ga nukeru yume) are among the most frequently searched dream interpretations in Japan. (ref: ntv.co.jp/mindofjapanese/articles/3770c0tlqt1hcp1pct8b.html)

These interpretations include ageing or physical decline, appearance or losing face, communication or relationships, health or death. Having such a dream is a bad omen that such calamities will happen soon.

Verity:

There's absolutely no scientific evidence that tossing a baby tooth in any direction affects how the new one grows. Tooth alignment is determined by genetics, jaw size, and habits such as thumb-sucking. And anyway, it's unlikely that a child could successfully throw a tooth under the floor of a house, since most are built on concrete these days. And also unlikely they could throw it onto the roof, especially if they live in a high-rise apartment block.

As for yaeba, crooked canines mean you'll be unable to chew properly, be more susceptible to cavities and periodontal disease because you'll be unable to brush your teeth properly.

And having dreams about teeth falling out ignores basic psychology and common sense. The content of a dream is subjective and influenced by personal thoughts, experiences and stress; not by supernatural forces. Dreams reflect the mind, not the future. Multiple studies suggest that teeth-falling-out dreams are common in people under stress. The dreams are a response to stress, not a harbinger of doom.

More Japanese superstitions