This book:
Making It: Radical Home Ec for a Post-Consumer World
has a mouthwash recipe in it, haven't tried it yet but plan to soon. But I
have been brushing my teeth with a chew stick as described in the book for the last 2 months and love it! No more plastic for brush for this guy! There are recommended species of twig to use, so far oak makes the most sense in my situation, but I'd like to experiment with others if I can find alternatives not printed in this book.
The great things about brushing with a stick?
-the obvious one: it's completely natural, renewable, compostable, inexpensive, etc.
-you don't need toothpaste so brushing can be an enjoyable way to unwind while reading or just sitting instead of a daily chore performed standing in front of a bathroom sink.
-because it's not a chore, you're likely to be more through and pay better attention to your teeth while getting them really clean. To be cautious though, I'd recommend flossing more.