Why use Essential oils?
Why not use the herb itself?
I make a Rosemary mouthwash using fresh rosemary. I brew tea and then I keep the mouthwash (tea) in the refrigerator until it is all gone.
I find Essential oils are expensive so I only have a few that I use sparingly. I inhale them, either directly out of the bottle or by using a diffuser.
I like Dr. Axe so I asked, his recipe adds calcium carbonate. Other recipes I saw use baking soda or salt instead:
https://draxe.com/beauty/homemade-mouthwash-with-essential-oils/
In the comments, someone said if calcium carbonate is not available use a crushed multivitamin or honey.
I like the idea of trying honey since I have honey.