I read this about 15 years ago in a book published a decade or two before that, IIRC. Unfortunately the book did not really make a case, just claimed there was

I read this about 15 years ago in a book published a decade or two before that, IIRC. Unfortunately the book did not really make a case, just claimed there was no evidence. It was a book about evidence-based medicine before that was a popular term (unfortunately I've also lost the name the book). My dental hygienist recently told me that I have to shove bits of wood between all my teeth twice a day. I asked why I hadn't heard this before and for how long, and she said "for the rest of your life because it's good for you". Hmm.