Sage - Salvia officinalis
Originally I read that Sage is used to prevent hyperhydrosis (excessive sweating) so I started drinking it 2 times a week during summer. As an unintended consequence my oral hygiene improved dramatically. I had gum bleeding when I brushed my teeth for years albeit using a mouthwash and brand toothpaste.
By drinking sage-tea and now switching to a (admittedly rather expensive) organic sage-toothpaste my oral hygiene improved dramatically: I haven't had gum bleeding for months and much less gingivitis.
Just in case something hurts or I have some inflammation of the gums I use a lidocaine hydrochloride solution that stops the sensation of pain. This liquid can be used for children with teething starting from 5 months of age and works pretty well for me.
As a side note: Sage is a quite undemanding plant to cultivate and grows in my garden.