Comment by thedentist1

Cavities are caused by sugars (and sugars only), so in theory, if you just eat green vegetables and meat, you shouldn't get any cavities. Veggies contain fibers and the consensus is that they exert a light brushing action on teeth (think when you chew celery and such)

A great resource for these questions is nutritionfacts.org (free and full of references to scientific studies)