Q. If little pieces of food that usually require flossing are stuck in the mouth and teeth after eating, can he go out with them to the street if there is no eruv?
What if one has a loose tooth or a filling, that will likely fall soon, can he go out to the street?
A. Minchas Yitzchok (5: 38) Minchas Shabbos and others maintain that one should preferably rinse the mouth after a meal, before exiting to a reshus horabim on Shabbos.
Oz Nidberu (7: 43), R’S’Z Auerbach zt”l quoted in Shemiras Shabbos K’ (18; 8) asserts it is unnecessary, and it is only an issue if the food particles between the teeth are bothersome or are unseemly, otherwise they are considered as part of the body.
Poskim above are also lenient in regards to loose teeth and fillings that are still attached even if they are bothersome and will soon be extracted or become detached. (Piskei Teshuvos 303: 5). Rivavos Efraim (3: 221) permits having a piece of a cotton-wool ball recommended by a dentist on a tooth, if it stays in place.
Horav Shlomo Miller’s Shlit’a opinion is also to be lenient, as we don’t usually carry in a Biblical public domain.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a