I have seen the Messenger of Allah (ﷺ) using a tooth-stick while he was fasting. Musaddad added in his version: "more often than I could count."
Sunan Abi Dawud Book 14, Hadith 52
← Previous Hadith The Prophet (ﷺ) as saying: Fast is a shield ; when one of you is fasting, he should neither behave in an obscene manner nor foolishly. If a man fights or abuses him, he should say: I am fasting, I am fasting.

Sunan Abi Dawud Book 14, Hadith 51 Next Hadith → AbuBakr ibn AbdurRahman reported on the authority of a Companion of the Prophet (ﷺ): I saw the Prophet (ﷺ) commanding the people while he was travelling on the occasion of the conquest of Mecca not to observe fast. He said: Be strong for your enemy. The Messenger of Allah (ﷺ) fasted himself.

Narrated AbuBakr:

A man who narrated his tradition to me said: I have seen the Messenger of Allah (ﷺ) in al-Arj pouring water over his head while he was fasting, either because of thirst or because of heat.

Sunan Abi Dawud Book 14, Hadith 53