I used to work for a dentist, and what they recommended for people who drank gatorade was, to use a straw. Probably not a real feasible thing to do while riding, I know --

There is (over the counter), a moisturing mouth spray for Dry Mouth by Sensodyne called "Oasis". You can purchase this at any Walgreens, CVS, etc.... It's a little one ounce spray that you can easily keep in the back of your jersey when riding. (it's minty flavored).

This "Oasis" also comes as a mouthwash/rinse, too.

Denise