Well, I couldn't find that link... but I did discover something equally interesting along the way: check out http://www.centerforintegrativedentistry.com/gum_disease/ind... and scroll down to the "oxygenation" section.

It seems that the more exercise you get, the more oxygenated your gums are, and (gum disease) germs survive better the less oxygen there is- so marathon runners have an extremely low incidence rate of gum disease! wow.