I make a rosemary mouthwash that can be used as a gargle. It is basically a rosemary tea.
Wellnessmama has a good recipe for a tinture that combines cloves, peppermint, plantain, rosemary and cinnamon:
https://wellnessmama.com/8343/herbal-mouth-wash/
I have not made this one though I know cloves, plantian and rosemary are good for healing mouth and throat problems. I prefer teas over tintures in this case.