So further to both herbal tooth powders and herb salts...
... here's a pic of fresh parsley with seasalt. The next step for both tooth powder and herb salt is to dry the mix; this lot is already on a piece of waxed paper (brown), and it went into the dehydrator for a few hours. After it was dry (the parsley crumbled completely) I powdered it in a vitamix.
Use as a tooth powder: pour a pinch onto a wet toothbrush, brush.
Use as a herb salt: sprinkle onto food.