The toothbrush on the left shows a smear of toothpaste and the one on the right a pea-sized amount.

Fluoride Toothpaste Before Age 2

Parents should use a tiny smear of fluoride toothpaste to brush baby teeth twice daily as soon as they erupt, instead of waiting until children are older, according to new guidelines by the American Dental Association. That advice overturns the A.D.A.’s decades-old recommendation to start using a pea-size amount at 24 months. Once children are…