Toddlers who drank lots of juice or who ate candy more than once a week were nearly twice as likely as their peers to have a mouthful of cavities by kindergarten, according to a 2001 study published in Dentistry and Oral Epidemiology. Interestingly, toddler tooth brushing habits were no different in the group that had cavities than in the group that was cavity-free. Tooth brushing remains an important habit to teach kids, but in the early years they are not very effective at keeping their teeth clean. Avoiding prolonged contact with sugary drinks or treats is a central part of growing healthy teeth.