I am skeptical that it is physically possible for water to be retained in a child's mouth long enough to make a difference. Might the 25% also have something to do with introduction of enhanced dental care, and encouraging frequent brushing of teeth with fluoridated toothpaste? You know, the stuff that leaves a significant residue, and is not completely wet and slippery?
I'm also skeptical whether you realize that "fluorinated water" is rather impossible. Fluorine is a gas, and a highly reactive one. It will explode (oxidize) if you mix it with water, you know. So, for your 25% factoid, [citation needed].
