Check out this article for what causes tooth decay. By the way I don't buy it re the mouth wash comment. That's good stuff and helps keep the gums healthy and prevents some root canals, I think. My husband had problems with his gums until he started using mouth wash and if one gets sore gums, nothing heals it faster than mouth wash. Anyway, just our opinion, but open to other ideas.
Clearly they recommend eating low-carb.