The American Dental Association recommends fluoride-free toothpaste for children under 2. For children under 6, the Centers for Disease Control recommends "child-strength" toothpastes with around 0.08% fluoride

or about 1/2 of what's found in regular strength toothpaste. Low fluoride children's toothpaste is common in the E.U. but hard to find in the U.S. If your children use a fluoride toothpaste, make sure they use a pea-sized amount and thoroughly spit and rinse.