Interesting -- I think the hypothetical causal chain I've read would be a bit less direct, like fructose/sucrose -> fatty liver -> metabolic syndrome -> lots of bad stuff like heart disease and diabetes. Also processed foods are low in various nutrients, like fat-soluble vitamins essential to maintaining bone and teeth, And mouth pH apparently matters too -- though I haven't read up on that at all. (I'm still starting on this stuff -- mainly going by Gary Taubes's _Good Calories, Bad Calories_ and the blog I linked to.) And, not relevant to teeth AFAIK, but the right kinds of dietary fats make a big difference -- that part I've noticed from experience, even.

On grains: http://wholehealthsource.blogspot.com/search/label/lectins and http://wholehealthsource.blogspot.com/search/label/celiac