Tooth Decay in Children: Causes, Treatment and Prevention
Tooth decay in children, called early childhood caries in under-sixes, is common and preventable. This guide for parents and carers covers causes, warning signs, treatment and prevention, hidden sugars included. Baby teeth hold space for adult teeth, so decay in them needs a dentist's attention.
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Clinically reviewed by Dr Ibraheem Ijaz, dentist · GDC 301711
Medical disclaimer: This page is for general information only. It does not replace an examination or treatment by a dentist.
Dr Ibraheem Ijaz, GDC 301711, principal dentist at Deepcar Dental Care, reviewed this page. He is a General Dental Practitioner with a BDS, BSc (Hons), MSc (Leeds) and postgraduate qualifications in implant, restorative and aesthetic dentistry.
What is tooth decay in children?
Tooth decay in children is the gradual breakdown of a tooth by acid from plaque bacteria. In the baby teeth, or primary dentition, of children under six, it is called early childhood caries.
The IAPD Bangkok Declaration, an international consensus, defines early childhood caries as any decayed, missing or filled surface, due to decay, on a baby tooth of a child under six. It was once called baby bottle tooth decay, or bottle decay. Early decay can be reversed; once it reaches the dentine under the enamel, it can progress to a cavity.
Why do baby teeth matter?
Baby teeth matter because they hold the space the adult teeth grow into, and they help a child chew, smile and speak clearly.
Holding that space makes crooked or crowded adult teeth less likely, NHS guidance for parents says, and SDCEP guidance notes the baby back teeth usually stay until about 9 to 12. Decay in baby teeth may lead to chronic pain and infection, the IAPD Bangkok Declaration adds.
Tooth decay is the most common reason children aged 5 to 9 are admitted to hospital in England. In 2024/25, Yorkshire and the Humber, which includes Sheffield, had the highest regional rate of hospital extraction episodes for decay: 504 per 100,000 under-20s, against 251 for England.
How does tooth decay start in children?
Tooth decay in children starts when bacteria in plaque turn sugar into acid, which slowly dissolves the surface of the tooth.
Early childhood caries is a sugar-driven disease with many contributing factors, says the IAPD Bangkok Declaration. A 2022 expert consensus lists decay-causing bacteria, especially Streptococcus mutans, and enamel defects among them, though Streptococcus mutans presence does not always match how severe decay is.
How often teeth meet sugar matters as well as how much, the NHS explains. Delivering Better Oral Health, the toolkit dental teams in England use, says acid in plaque takes 20 to 40 minutes to clear after each sugar intake, helped by saliva, and advises avoiding sugar at bedtime, when saliva flow drops.
What are the warning signs of tooth decay in a child?
The NHS lists toothache, sharp pain with hot, cold or sweet things, and white, brown or black spots as signs of a child's tooth decay. Early decay may cause none; they can appear once a hole forms.
If you think your child has tooth decay, see a dentist as soon as possible, the NHS advises. See one too for toothache or sharp pain when eating or drinking, or gums that are painful, swollen or bleed when brushing. This matters most if toothache lasts more than 2 days, painkillers do not help, or it comes with a high temperature, pain when biting, red gums, a bad taste or a swollen cheek or jaw. With no dentist or emergency appointment, call 111 or use 111 online. Children under 16 should not take aspirin.
Go to A&E if toothache comes with swelling around the eye or neck, or swelling in the mouth or neck that makes it difficult to breathe, swallow or speak. Do not drive: ask someone to take you or call 999.
To ask about your child's teeth, book online or call 0114 288 2121.
How is tooth decay treated in baby teeth?
Tooth decay in baby teeth is treated by severity, and SDCEP guidance asks dentists to choose the least invasive option that will work.
| Stage of decay in a baby tooth | What SDCEP and NHS guidance describe |
|---|---|
| Early decay, white spots, no hole | Fluoride and less frequent sugar, or a sealant on a back tooth, checked at each visit |
| A cavity, healthy dentine over the nerve | A filling, or for a baby molar the Hall Technique: decay sealed in under a preformed metal crown, no injection or drilling; decay progresses if the seal fails |
| Decay in the nerve, lasting pain, no abscess | Pulpotomy, removing diseased nerve tissue and fitting a crown, or removing the tooth |
| An abscess | Usually removing the tooth, even without pain |
A dental abscess, a build-up of pus from an infection that decay can cause, needs an urgent dentist appointment or help from NHS 111. Call 999 or go to A&E if your child finds it hard to breathe, speak, swallow or open their mouth, has a swollen or painful eye or sudden eyesight problems, or has a lot of swelling in the mouth.
Where a child cannot cope with treatment, or many teeth are affected, SDCEP advises the dentist to consider referral to assess suitability for treatment or extraction under sedation or general anaesthetic.
How can you help prevent the next cavity?
Preventing the next cavity rests on fluoride and on cutting how much and how often teeth meet sugar, says Delivering Better Oral Health.
NHS advice is for a parent or carer to brush, then supervise, twice a day, including last thing at night, with at least 1,000ppm fluoride toothpaste: a smear up to age 3, a pea-sized amount from 3 to 6, and 1,350ppm to 1,500ppm from 7. Spit out, do not rinse.
The NHS says children should be offered fluoride varnish, painted onto the teeth, at least twice a year from age 3, and younger children if the dentist thinks they need it. Our page on how fluoride works has more.
Frequently asked questions
Do baby teeth with cavities need filling?
Not always. SDCEP guidance asks dentists to choose the least invasive option for each baby tooth, such as sealing the decay in, a filling, a preformed crown or monitoring. A tooth close to falling out may need no treatment if it is unlikely to cause pain or infection first.
What does a black spot on a child's tooth mean?
A black, brown or white spot can be a sign of tooth decay, according to the NHS. Decay may cause no symptoms at first, so show the spot to a dentist even if your child seems fine. Early white-spot decay in the enamel can be reversed with fluoride.
Can bottle feeding cause tooth decay?
It can when a bottle holds juice or sugary drinks, the NHS explains. Delivering Better Oral Health advises only breast milk, infant formula or cooled boiled water in a bottle, a free-flow cup from 6 months and moving off bottles from age 1. At night, the NHS advises the same drinks only.
Is fruit juice bad for children's teeth?
Fruit juice contains free sugars, even unsweetened, and its acid can harm teeth. The NHS recommends milk and water for young children. If you give juice, keep it to mealtimes, dilute it 1 part juice to 10 parts water and give no more than 150ml a day.
How often should a child have a dental check-up?
Delivering Better Oral Health advises a check-up interval of 3 to 12 months for children. It depends on oral health and decay risk, and is shorter where risk is higher. The NHS advises seeing a dentist if an under-18 has had no check-up for a year.
Book a consultation.
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Book online through the booking portal or call 0114 288 2121, 8am to 8pm, Monday to Sunday. Children are welcome at Deepcar Dental Care from any age, and we usually suggest a first visit by 3. A child's first visit is just a look and a chat, with no treatment.
Children's dentistry is part of our general dental services, the routine care our dentists provide; our children's dentistry page covers care from first tooth to teens.
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