Tooth decay (dental caries) in baby teeth is one of the most common diseases of childhood worldwide. The World Health Organization estimates that hundreds of millions of children have untreated decay in their primary teeth. It causes pain, infections, difficulty eating and sleeping, missed school and, sometimes, hospital treatment under general anaesthetic. Yet it is almost entirely preventable.
This guide explains how tooth decay happens, the early signs to look for, how much toothpaste to use at each age, bottle and sugar habits that cause damage, and when to see a dental professional.
Imagine a three-year-old who cries at night and refuses to eat. His parents think he is teething or being fussy. When a nurse looks in his mouth at a clinic visit, she sees brown holes in his front teeth. He has gone to sleep with a bottle of sweetened tea every night since he was one. He needs several teeth treated. His parents are shocked: nobody told them that a bedtime bottle could do this.
Why baby teeth matter
- They help children eat, speak and smile with confidence.
- They hold space for adult teeth; early loss can cause crowding.
- Decay causes pain and can lead to abscesses and infection.
- Children with decay in baby teeth are more likely to have decay in adult teeth.
How tooth decay happens
Bacteria in dental plaque feed on sugars and produce acids that dissolve tooth enamel. Frequent sugar, especially between meals and at night, gives acids more time to attack. Saliva and fluoride help repair early damage, but if attacks are too frequent, holes (cavities) form.
Early signs
- White chalky spots near the gum line (early decay, which can be reversed).
- Brown or black spots or holes.
- Sensitivity to sweet, hot or cold foods.
- Bad breath.
- Pain, swelling of the face or gums, or fever (urgent).
Toothbrushing by age
| Age | What to do |
|---|---|
| Before teeth | Wipe gums gently with a clean, damp cloth |
| First tooth to 3 years | Brush twice a day with a smear (rice-grain size) of fluoride toothpaste |
| 3 to 6 years | Brush twice a day with a pea-sized amount of fluoride toothpaste |
| Until about 7 to 8 years | An adult should brush or supervise brushing |
| All ages | Spit out, don’t rinse, so fluoride stays on the teeth; brush last thing at night |
Follow the fluoride guidance used in your country, as recommendations vary slightly.
Food and drink habits
- No bottles in bed with milk, juice, tea or sweetened drinks.
- Water and milk are the best drinks between meals.
- Limit sugary foods and drinks to mealtimes, not snacks throughout the day.
- Avoid adding sugar to baby foods, tea or pap.
- Introduce a cup from around six months and aim to stop bottles by around one year.
- Check medicines: ask for sugar-free versions when possible.
- Healthy snacks: fruit, vegetables, plain yoghurt, nuts (for older children, as choking risk allows), boiled eggs.
Breastfeeding and teeth
Breastfeeding is recommended and protects children’s health. Once teeth appear, keep up toothbrushing with fluoride toothpaste and avoid adding sugary foods and drinks, especially at night.
First dental visit
Many dental organisations recommend a first visit when the first tooth appears or by the first birthday. If dental services are limited, ask a nurse at the child welfare clinic to check your child’s teeth at routine visits.
When to seek urgent care
- Facial swelling.
- Fever with tooth pain.
- A knocked-out or broken tooth after injury.
- Severe pain that stops eating or sleeping.
See our guide to toothache and dental emergencies.
Teething is not decay
Teething can cause drooling, gum rubbing and mild irritability, but not high fever or holes in teeth. Read more about teething.
Frequently asked questions
When should I start brushing my baby’s teeth?
As soon as the first tooth appears, twice a day, with a smear of fluoride toothpaste.
How much toothpaste should children use?
A rice-grain smear under 3; a pea-sized amount from 3 to 6 years.
Can bottle feeding at night cause decay?
Yes, especially with sweetened drinks or juice. Avoid bottles in bed.
Do baby teeth need treatment if they will fall out?
Yes. Decay causes pain and infection and can affect adult teeth.
But my child hates brushing?
Many do. Make it a routine, sing a song, let them hold a brush too, brush together, and lie them on your lap to see better. Two minutes, twice a day, will protect their smile for years.
Your next step: Tonight, check your child’s front teeth near the gums for white or brown spots, and make the last thing in their mouth at bedtime fluoride toothpaste, not milk or juice.
Related: Teething · Toothache and dental emergencies · First 1,000 days nutrition
Sources: World Health Organization Global Oral Health Status Report (2022); national public health guidance on fluoride toothpaste for children; FDI World Dental Federation.
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