When Julia James took her daughter in for a first dental checkup, she got some news that would set most parents' teeth on edge: little Juliet, age 4, had 13 cavities. That's quite a shocker, particularly when you consider that children have only 20 baby teeth. "I was surprised to hear that her teeth weren't the worst the dentist had seen," says James, of Claremont, California. Indeed, tooth decay is extremely common in kids--largely because many parents think first teeth are "just baby teeth" and therefore expendable. "We really need healthy baby teeth," says Arthur J. Nowak, DMD, executive director of the American Board of Pediatric Dentistry. "They prepare the mouth for permanent teeth and help with language development." Brush up on how to keep that sweet smile cavity-free for years to come.