Parents should no longer wait until a child turns two to start brushing baby teeth with fluoride toothpaste, the American Dental Association says.

Instead, parents should use a rice-grain size smear on a child’s first teeth and move up to pea-size blobs once the child reaches age three, the group says in updated guidelines published in the February issue of the Journal of the American Dental Association.

The policy change from the nation’s largest dentists’ group is in line with advice from the smaller American Academy of Pediatric Dentistry. But it may come as a surprise to parents who have long heard that they should wait to use fluoride.

The new advice from the ADA was prompted by concern about the 25% of U.S. children who develop cavities before kindergarten, according to a statement from Edmond L. Truelove, chair of the group’s Council on Scientific Affairs.

A scientific review concluded that using small amounts of fluoride toothpaste would help prevent cavities while minimizing the risk of fluorosis – a discoloration that can occur when teeth are exposed to too much fluoride early in life.

To further minimize risk, children should be taught to spit out excess toothpaste as soon as possible, the ADA says.