I had terrible tooth decay when I was younger (I have 16 fillings from ages 10-20). And then, all of a sudden - nothing. I haven't had a hole or a problem since (except for a filling that broke and had to be replaced). There was nothing that I'm aware of that I changed around that time -- I stopped drinking sodas and eating junk food around age 30.

But I have recently read claims (and testimonials) that what you need for healthy teeth is Vitamin D (make sure you take it in the morning if you do!) and Vitamin K2, see e.g. http://www.thedentalessentials.com/The_role_of_vitamin_k2_on... ; If you find this interesting, you'll find a lot more similar stuff on the bulletproof executive forums.