The Law Code of Devala 1.6: Kṛtyakalpataru · Madanapārijāta · Smṛtiratnākara +4

1.6

bhojane dantalagnāni nirhṛtyācamanaṃ caret | dantalagnam asaṃhāryaṃ lepaṃ manyeta dantavat || na tatra bahuśaḥ kuryād yatnam uddharaṇe punaḥ | bhavec cāśaucam atyantaṃ tṛṇavedhād vraṇe kṛte

Having approached Devala, best of sages, / who was seated comfortably on the bank of the Indus, all the sages spoke these words:

After eating he should remove what sticks to the teeth and then sip water; what sticks to the teeth and cannot be removed he should regard like the teeth themselves. He should not try too often to remove it, for if a wound is made by pricking with a straw there is great impurity.