Also, Southeast Asia probably means drinking green tea, which equals fluoride, thus good for teeth (up to a point). Relatedly, I remember hearing of archaeolog

Also, Southeast Asia probably means drinking green tea, which equals fluoride, thus good for teeth (up to a point). Relatedly, I remember hearing of archaeologists finding skulls of "cave men" (can't remember the time or place) with perfect teeth and signs of tooth picks (grooves around the gum line). The implication was that cultural knowledge (or perhaps just personal habits) had solved bad dental hygiene at times throughout history--and it was repeatedly lost and found again. Could have also been happenstance with natural fluoride in the water (how the effect was discovered, I believe), or non-intentional as with the green tea.