This is a colloquial term for teeth that are arranged in a twisted or overlapping manner, or for the teeth themselves. It is derived from the resemblance of a spike being driven into the teeth in an out of order manner. It is mainly used when it is seen in the front teeth of the lower or upper jaw, but it can also be applied to molars. The first cause is that the jaw in which they are arranged is too small compared to the size of the teeth. The second cause is that the replacement of baby teeth with permanent teeth does not proceed properly, either because baby teeth remain for too long, or, conversely, because baby teeth fall out early due to cavities or other reasons, and the permanent teeth are not given the proper space to grow in. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
歯がねじれたり重なり合って並んだ歯並び,あるいはそれらの歯をさし,歯の叢生の俗称である。ちょうど杙が列を乱して打ち込まれている状態に似ていることに由来する。下あごの前歯や上あごの前歯にみられるときおもに用いられるが,臼歯にもあてはめることがある。原因の第1は,歯の大きさに対して,それらが並ぶあごの大きさが小さすぎることである。第2は,乳歯から永久歯への生えかわりがうまく進まなかったためで,乳歯が長く残りすぎたり,逆に乳歯が虫歯などで早く抜け,永久歯が生える場が正しく与えられなかったことによる。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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