George Washington's Rules of Civility Traced to their Sources and Restored by Moncure D. Conway
Chapter viii. 36. Ne vous nettoyez pas les dents auec la nappe, ou
la seruiette, ny auec le doigt, la fourchette, ou le cousteau. Ce seroit faire pis de le faire auec les ongles, mais faites-le auec le curedent. Aussi ne semble-il estre bien-seant de se les nettoyer en table, si ce n'estoit que les autres le fissent, & que ce fust la coustume des mieux ciuilisez.
Do not clean your teeth with the tablecloth, napkin, finger, fork, or knife. It were still more objectionable to do so with the nails. Use a toothpick. It also does not appear well-bred to pick them at table, unless others do so, and where such is a custom of the more gentlemanly.
101st. Rince not your Mouth in the Presence of Others