Can we improve our teeth by eating certain foods?

my aunt had told me that apples keep or make teeth clean/white. i thought it was like a dream because it was so long ago that she told me, i was still a kid. but now, recently i asked my mom that if it was true if, by eating apples will maintain our teeth white/clean, and she nod her head yea.

see rural inhabitants of both india and Africa regularly use neem (Azadirachta indica) as tooth brushes. neem twigs contain antiseptic ingredients. that explains how these rural people are able to maintain good healthy teeth and gums in comparison to urban people. neem in the form of powder is also used. besides if you talk about eating habits, urban people i think eat more of sugars like toffees, chocolates etc that are more likely to harm their teeths

Rural people eat corn,jowar and bajra every day,they take milk of goat,sheep and camel,they drink buttermilk that is very higenic,it keeps the digestive system clean.They work very hard they have made their bones and muscles very healty.They have very good amount of calcium in body that keeps their bone and teeth healthy and strong.