I had the same problem: not really from Gatorade per se, but just too much stuff with sugar during long rides. My solution: I take my toothbrush and a very tiny tube of tootpaste in my pocket, and brush once en route. Usually, if I am out on a long ride, I have time to stop and do this. Also, I brush again straight away when I finish riding. The key is really to get the sugar out of the mouth. This has worked well for me: no more new cavities (still keeping the fingers crossed).