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."  

رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَسْتَاكُ وَهُوَ صَائِمٌ زَادَ مُسَدَّدٌ مَا لاَ أَعُدُّ وَلاَ أُحْصِي