Innercore from 550 cord is great dental floss. It`s a little thick but who doesnt like a smile that looks like a picket fence
Chewing on a green stick from a known/safe species has been mentioned for tooth brush.
Goats beard/witches hair as a natural scrubbie pad for teeth and body,as well as cooking gear. i would think other lichens would also work well.
Use your shirt to scrub teeth periodically.
Tooth care is and has been a major point due to the number of P.O.W. `s who experienced dental problems in captivity... thats why we go to the dentist prior to deployment to this day.
As far as body,
The smokeing the feet was more to dry them in a wet environment, which covers numerous biomes. and the heat and smoke kill bacteria.
Scrubbing hands and body with sand from a creek will remove dead skin and remove bacteria.Nothing wrong with getting in the creek for a sand bath all over other than shrinkage....
Ground Alum root was used back when as a starch substitute (natures goldbond). I`ve used it and can attest to the need to grind it more than you think it needs :0.....but it does work on feet and crotch.
manty plants can be pulverized to create soap for body and clothes, and scrubbing clothes to remove blood, dead skin , sweat ETC will prevent bacteria from staying in contact with body. Even air baths are better than nothing (Ben Franklin was a fan)
In a long term survival situation (non combat) it is the creases,folds and contact areas of the body that suffer the most and are succeptible to heat rash,body sores,infection and parasites, so wash there often, dry often and inspect daily.
I`m a fan of fire for its ability to steralize, dry, kill bacteria...on just about any surface.
In the field we used a handfull of grass to initially scrub cook kits etc and then sand to scrub burnt food out. Do this away from the creek to ensure you dont contaminate anybody downstream, as well as keeping any soap out of the watersource. This may also be usefull for setting up a blind also as animals were attracted to the food residue if it didnt have soap in it and was away from camp....