永久歯

1. Origins, structure, and basic meaning

• Structure: 永久歯, read えいきゅうし, combines permanence 永久 with tooth 歯 as a dental category name.
• Basic usage: It denotes the teeth that replace baby teeth and generally are not replaced again, as in 乳歯と永久歯.

2. Common pitfalls and similar expressions

• Distinguishing meanings
  • It is a tooth category contrasting with temporary 乳歯; the name does not mean the teeth can never be damaged.