In the 1930's a nutritionist doctor duuude named Weston Price went all over the world documenting people's diets and the effect on dental health. He found that pre-advent of the modern diet(white refined sugar, some flour) that people were MUCH healthier. And in cultures that did not know a tooth brush, but did not have a modern diet. Tooth decay was almost unheard of.
That one is self-explanatory.
This one begs a little more explanation. These brothers are twins, identical in every way save one. The one on the right had marmalade on his toast in the morning, and refined white sugar in his tea. These two dietary differences produced vastly different chompers. Both consumed a diet of potatoes, organ meats and coarse grains(the basic diet of the Hebrides). Only difference was sugar.
Sugar fucks witcho teeth bruh. Stop drinking monsters and red bulls, it's killing you.