To instill lifelong habits to protect one’s smile, experts recommend that tooth brushing begin early in childhood. To accomplish this, the American Academy of Pediatrics advises the following: wipe your baby’s gums with a soft, clean washcloth; never give your baby a bottle in the crib; introduce solid healthy food choices to avoid tooth decay; brush your child’s teeth twice daily until the age of three using a smear of toothpaste the size of a grain of rice; and children age three and older should be able to brush their teeth twice daily by themselves with adult supervision using a pea-sized amount of toothpaste.
American Academy of Pediatrics, December 2017