Among the great American contributions to civilization

As I realize, now in my near-middle 60s, that I am no longer going through puberty (thank God America still is), I have aspirations to write a "definitive" history of dentistry, with a focus on the USA. Compare teeth-hygiene in our "homeland" with that of other countries (including the notoriously-bad-teeth UK, from whom we thankfully separated in 1776)

and you see a wonderfully concrete sign of human progress. Dental floss: Among the great American contribution to civilization. God Bless America. Image from