My son is 16 mo., vegetarian and has no cavities...I have no cavities and have been vegetarian for half of my life (I'm 30, too). I also never drank milk and rarely ate eggs for much of my young life (I was allergic as a young child).
I have a friend who was raised vegetarian who, too, had no cavities until much later in life.
I really believe that cavities come from an acidic value to the saliva, sometimes in combination with genetics, other times in combination with diet...
I recently switched from the Weleda Calendula to a tooth powder made of Myrrh, Baking Soda, and Kelp and have noticed it fizz a couple of times while brushing...like there is an acid/base chemical reaction taking place in my mouth. I feel like my mouth is much cleaner, my teeth white, and the overall hygiene of my teeth is better since the switch. I've never looked into my suspscions about tooth powder being better for the teeth than the glycerin based pastes, but I truly feel a difference.
I also read on an earlier thread that the glycerin contained in most natural toothpastes coats the teeth, hence inhibiting the natural benefits of saliva in remineralizing teeth. Here is the link:http://www.mothering.com/discussions...12#post7721212
There are, additionally, some threads that you might find interesting within this section if you search under early childhood caries or something similar:http://www.mothering.com/discussions...play.php?f=308
There are also a couple of articles in the archives...do a google search under something like "early childhood caries Mothering" to find that...I don't have the link anymore.
I have a friend whose dd, oddly enough, was born on the same day as your daughter, who has cavities as well. I did some reseach for her.
Good luck, mama