Make your own toothbrush.

I've made loads of toothbrushes from licorice sticks (Glycyrrhiza glabra). It's easy:
Pic: Licorice toothbrushes soaking in vodka.

• Boil a handful licorice sticks (medium thickness - 5 mm is about right, 3 mm too thin, 7 mm too thick) with 3-4 cinnamon sticks and about 10 cloves. If you like you can add ginger, as well.
• Let simmer until the sticks are soft. This takes about 4-5 hours.
• Strain out the licorice sticks and put them into a longish container.
• Cover with vodka, close lid on that longish container.
• Let sit overnight.
• Put sticks into dehydrator, let dry on full heat (about 60 deg. C) until dry.

Pic: Licorice toothbrushes on a dehydrator tray.

Using these toothbrushes: chew open 1-2 cm of one end, use that to brush with. You can't reach around corners. When the chewed-up bit is all untidy, remove the untidiness with scissors or a knife and chew up the next bit.

You're guaranteed to get interesting looks when you use this.

I got the recipe long ago from one or the other book by David Hoffman. I think (but I'm not sure) he recommends also trying birch twigs. If you want to boil birch twigs until soft you'll need to wait for a long time. Also, after boiling them for 4-5 hours you have birch twigs, not tooth brushes. They simply don't open up when chewed. I've tried it, it doesn't work.