Look for images from Weston Price’s book “nutrition and physical degeneration”, he toured the world a hundred years ago taking photos of teeth - it’s surprising that native tribal people all over had wide mouths not crowded teeth, no need for braces, they had white teeth and no need for fillings. Compared to today many in the west have narrow lower jaw, crowded crooked teeth and need many fillings.

Weston Price attributed it to nutritional deficit in our diets and suggested things like eating more organ meats, eat how traditional people did.

Then there’s sugar and fizzy drinks, sticky sweets, refined flour, cultivars of fruits chosen for sweetness, all very good for bacteria growing on the teeth causing tooth decay, and not so prevalent in the past with food being less sugary.

More recently John Mew has put forth the idea that chewing thoroughly involves pushing up with the tongue which is a strong muscle and it pushed out on the jaws from inside; over a childhood of chewing that causes the jaws to widen and teeth to have room. These days with processed convenience foods you can swallow in a couple of bites, children aren’t chewing as tough food for as long, and he suggests that’s a contributor to why modern people have teeth crowding and narrow jaw problems.