Home › Kids’ Dentistry › Cavity Prevention
Kids’ dentistry · Everyday habits for families
How to Prevent Cavities in Children: A Practical Guide for Parents
To prevent cavities, brush your child’s teeth twice a day with fluoride toothpaste (a rice-grain smear under 3, a pea-sized amount from 3 to 6), keep sugary snacks and drinks to mealtimes, and avoid bedtime bottles of milk or juice. Dr. Ho-seon Lee at Yonsei Baro, near Isu Station, adds check-ups, fluoride and sealants.
Cavity prevention at a glance
| Age | Fluoride toothpaste and brushing |
|---|---|
| First tooth to age 3 | A smear the size of a grain of rice, twice a day; a parent brushes |
| Ages 3–6 | A pea-sized amount, twice a day; a parent brushes or helps |
| Ages 6 and up | Pea-sized amount; supervise until about 7–8 |
| All ages | Spit out, don’t rinse; floss where teeth touch; regular check-ups |
How do cavities start?
Bacteria in dental plaque feed on sugars and other fermentable carbohydrates, producing acid that softens tooth enamel. Saliva and fluoride repair early damage, but if acid attacks happen too often, a cavity forms.
This is why how often your child has sugar matters as much as how much. A sweet dessert after dinner is less harmful to teeth than the same amount of sugar sipped or nibbled through the afternoon. Baby teeth have thinner enamel, so decay can spread quickly.
How much fluoride toothpaste should my child use?
- From the first tooth to age 3: a smear about the size of a grain of rice.
- From age 3 to 6: a pea-sized amount.
- Brush twice a day, for about two minutes, including last thing at night.
- Spit, don’t rinse. Leaving a little toothpaste on the teeth helps fluoride keep working.
- Supervise brushing until about 7–8. Most children don’t have the dexterity to clean well on their own until then. Let them have a go, then “check” with a second brush.
- Start flossing once two teeth touch each other, as a toothbrush can’t reach between them.
Store toothpaste out of reach of young children. If you have questions about fluoride, our page on fluoride treatment explains how professionally applied fluoride adds protection.
Snacks and drinks: what to watch for in Seoul
Many popular children’s products in Korea, as elsewhere, are higher in sugar than they look. Watch out for:
- Sweet yogurt drinks and flavoured milks. Handy and marketed to children, but often sweetened. Offer them with a meal rather than as a sip-all-day drink.
- Juice boxes and sports or vitamin drinks. Even 100% fruit juice is sugary and acidic. Water and plain milk are the tooth-friendly choices between meals.
- Sticky snacks. Jellies, chewy candies, dried fruit, sweet rice cakes and some crackers cling to the grooves of the back teeth. If your child has them, include them with a meal and brush or rinse with water afterwards.
- Frequent grazing. Long after-school academy days can mean constant snacking. Try to keep to a few planned snack times, with tooth-friendly options such as cheese, plain yogurt, fruit, vegetables or nuts (for children old enough to eat them safely).
Reading labels helps: in Korean, sugar is listed as 당류 ( dangnyu ).
Why avoid bedtime bottles of milk or juice?
When a baby or toddler falls asleep with a bottle or sippy cup of milk, formula or juice, the liquid pools around the teeth while saliva flow drops during sleep. This can cause rapid decay, especially on the upper front teeth. If your child needs a bottle to settle, fill it with water only, and brush before the final sleep. If night feeds continue once teeth are present, ask us for advice that fits your family.
How does the dentist help prevent cavities?
- Regular check-ups and cleanings find early, reversible changes and remove plaque that brushing misses.
- Fluoride varnish strengthens enamel and can help early soft spots harden again.
- Dental sealants cover the deep grooves of the back molars, where most childhood cavities start.
- Small cavities found early can often be treated with a simple tooth-coloured filling before they cause pain.
For children enrolled in Korea’s National Health Insurance, some preventive care, such as sealants on permanent molars, may be covered under certain conditions. Eligibility depends on age and other factors, and we confirm coverage at your visit. See Korean health insurance (NHIS) .
Is my child at higher risk?
Risk is higher with frequent snacking or sweet drinks, previous cavities, braces or other appliances, some medical conditions, and difficulty brushing. Dr. Ho-seon Lee will assess your child’s risk and suggest a check-up interval that suits them.
Let us know when you book that you’d like English support — Dr. Sally Chaekyung Lee and our team can help explain your child’s care in English.
Cavity prevention FAQs
Is fluoride toothpaste safe for toddlers?
Yes, in the right amount. Major dental organisations recommend fluoride toothpaste from the first tooth, using a smear the size of a grain of rice until age 3 and a pea-sized amount from 3 to 6. A parent should put the toothpaste on the brush, and the tube should be kept out of reach. Swallowing these small amounts occasionally is not a concern.
Are sweet yogurt drinks and juice bad for children's teeth?
They are fine as an occasional treat with a meal, but sipping them between meals exposes teeth to sugar and acid again and again. Many sweetened yogurt drinks and fruit juices contain more sugar than parents expect. For everyday drinks between meals, water and plain milk are the tooth-friendly choices.
At what age can my child brush their own teeth?
Most children can start brushing alone with supervision once they can tie their own shoelaces or write their name neatly, usually around age 7–8. Until then, let your child have a turn first, then brush again yourself to make sure every surface, especially the back molars and gum line, is clean.
My child already has a cavity. Is it too late for prevention?
Not at all. Prevention protects the teeth that are still healthy and reduces the chance of new cavities. The existing cavity should be checked and treated so it doesn’t grow or cause pain, and then a plan of brushing, diet changes, fluoride and possibly sealants helps keep the rest of your child’s teeth healthy.
Medically reviewed by Dr. Ho-seon Lee
Board-certified pediatric dentist (Korea Ministry of Health and Welfare) · Director of Pediatric Dentistry · Last updated October 2026
This page is general information, not a diagnosis. Every child is different; your child's dentist will recommend care after an examination. In an emergency involving breathing, heavy bleeding, a head injury or facial swelling spreading toward the eye or neck, call 119.
Help your child keep a healthy smile
Book a check-up and we will assess your child’s cavity risk and suggest a plan. Contact us for pediatric dentistry appointment times. Isu Station Exit 2, Seoul.