Often when we are told to picture a medieval peasant, people immediately picture a person with teeth rotting out(if they have teeth at all). In reality, peasants teeth were surprisingly amazing.
There are two theories as to why; one is that they chewed their food more, and the other(and the one I tend to believe more) is that they have great teeth because of the lack of sugar in their diet.
Medieval peasants ate fish, fruits and veggies, and breads, but not much in the way of sugars. Mostly, the only sugars they ate were fruits and veggies, which are not nearly as bad for teeth as the refined sugars we eat today.
Another reason why their teeth were great is that they did care for them. This will break the image of “barbaric” medieval people for many readers, but sorry, the people of medieval times cared just as much about appearance as we do. Both good teeth and breath were considered desirable traits, so people did what they could to keep that.
Rough clothes were used to clean teeth and gums(like toothbrushes), sage, mints, and other aromatic herbs were mixed to make breath smell great(like breath mints), and vinegar and other mixes were sometimes used to rinse smells from the mouth(mouth wash).
We have this image of medieval people having worse teeth than us, but in reality, that is just a myth.