乳歯

1. Origins, structure, and basic meaning

• Structure: 乳歯 is a noun read にゅうし, meaning a baby tooth that appears in childhood and is later replaced by a permanent tooth.
• Basic usage: It can describe a younger brother losing one baby tooth or baby teeth from childhood being kept in a box.
  • 弟の乳歯が一本抜けた。 says that one of the younger brother's baby teeth fell out; 箱の中に子どもの頃の乳歯が保存されていた。 says that baby teeth from childhood had been kept in a box.

2. Common pitfalls and similar expressions

• 乳歯が一本抜ける
  • 一本 uses the counter for long or slender items and shows that one baby tooth fell out.
• 箱の中に保存される
  • に marks the inside of the box as the place where the teeth were kept.
• 乳歯 and 永久歯
  • 乳歯 is a baby tooth from childhood, while 永久歯 is a permanent tooth that replaces it.