歯は元もと

noun

root of a tooth; tooth root

Refers to the part of a tooth embedded in the gum, including the root and surrounding area. Common in dental contexts.

• 歯は元もとが腫はれて痛いたい。

  The root of my tooth is swollen and painful.

noun

dedendum

Technical term in gear design: the part of a gear tooth below the pitch circle. Used in mechanical engineering.

• 歯は車ぐるまの歯は元もとの強きょう度どを計けい算さんする。

  Calculate the strength of the gear tooth dedendum.