I want to share an excellent blog post from a priest at Austin Zen Center. It's all about the connection between self-care and bodhisattvahood, and details a lot of interesting specifics about Dogen's opinions on dental hygiene:

Back then, folks chewed on the fibers of a willow twig to clean their teeth. Dogen does not approve of the 13th century Chinese custom of brushing the teeth with an ox horn and horse hair brush - he suspects that such a brush may be a "vessel of impurity" - but surely he would approve of the sanitary toothbrushes available in 21st century America? Perhaps we can replace his "willow twig" with "toothbrush."

"People who have clarified whether or not this willow twig is necessary may be bodhisattvas who have clarified the Buddha-Dharma. People who have never clarified [this matter] may never have seen the Buddha-Dharma even in a dream. This being so, to meet the willow twig is to meet the Buddhist patriarchs. For instance, if a person were to ask 'What is your intention?' [I would reply,] "You have been lucky to meet old man Eihei's chewing of the willow twig."
Apparently Dogen was also pretty anti-bad breath:

Dogen goes on to lament that the practice of chewing the willow twig had fallen out of fashion in China; "So monks and lay people throughout the country have terribly bad breath. When people speak from two or three feet away, the stench from their mouth is difficult to bear. Even those famed as venerable patriarchs who possess the truth, and those titled as guiding teachers of human beings and gods, do not know even of the existence of the practice of rinsing the mouth, scraping the tongue, and chewing the willow twig... It is regrettable. It is very regrettable."

"In sum, chewing the willow twig and washing the face are the right Dharma of eternal buddhas and people who are devoted to practicing the truth with the will to the truth should practice and experience them."
For god's sake Buddhas, brush your teeth so you don't make the truth stink!

I found all of this interesting and also hilarious. I like Dogen's practical side. I think that's why I liked the Shobogenzo Zuimonki so much.