1,103. Cleaning the Teeth
161:10 A woman must clean her teeth before immersing in a mikvah because it's common to find particles of food in the teeth. If she immersed and found something between or stuck to her teeth, the immersion is invalid. Some women have the practice not to eat meat on the day they go to the mikvah because meat is more likely than other foods to get stuck between the teeth. There is concern that even if she cleaned her teeth, some meat may remain, therefore this is a very good practice. On Shabbos and yom tov, when one eats meat, the woman must be careful to clean her teeth very well. A woman must be careful not to eat anything between her preparations and immersing in the mikvah. On the day of a woman's immersion, she should not handle dough or wax candles so that nothing sticks to her skin. If it's her practice to knead her own dough on Fridays in honor of Shabbos, she should not refrain from doing so but she must be sure to wash her hands thoroughly when she is finished.
161:11 If a woman has a false tooth, she must ask a halachic authority what to do regarding her immersion. The same is true of a woman who has a filling in a tooth or a ring inserted for a uterine hernia.