[173] Now at that time bhikkhus did not chew tooth-wood. Their mouths were foul-smelling. They reported this matter to the Blessed One. … "Bhikkhus, there are these five disadvantages in not chewing tooth-wood: it is harmful to the eyes; the mouth becomes foul-smelling; the taste-receptors are not cleansed; bile and phlegm envelop the food; and one's food does not agree with one. These, bhikkhus, are the five disadvantages in not chewing tooth-wood.
Bhikkhus, there are these five benefits in chewing tooth-wood: it is good for the eyes; the mouth is not foul-smelling; the taste-receptors are cleansed; bile and phlegm do not envelop the food; and one's food agrees with one. These, bhikkhus, are the five benefits in chewing tooth-wood. Bhikkhus, I allow tooth-wood."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.