Tooth decay in children is the gradual breakdown of tooth enamel caused by bacteria turning sugars from food into acid. It’s the most common chronic disease in UK children, affecting around one in four five year olds. Brushing twice daily with fluoride toothpaste and limiting sugary snacks prevent most cases.
At our paediatric clinic in Fulham, London, tooth decay is by far the most common reason worried parents bring their child to see us. The reassuring part is that almost every case is preventable, and when caught early, treatment can be quick, gentle and entirely free of fear. This guide explains why decay happens in young teeth, what the early signs look like, how to stop it before it starts, and what to do if your child already has a cavity. If you’d like to book a friendly check-up with a specialist children’s dentist, we’re here whenever you need us.
Tooth decay, also known as dental caries or cavities, happens when bacteria in the mouth turn sugars from food and drink into acid. That acid slowly wears away the protective enamel coating on teeth, and over time it creates small holes that can grow deeper if left alone. In children, decay tends to develop faster than in adults because young enamel is thinner and softer.
At the earliest phase, decay can sometimes be halted or even reversed through better brushing and fluoride. Once a hole has broken through the enamel, the damage is permanent and the tooth needs restoring. Spotting it sooner always means simpler treatment.
Tooth decay is widely considered the most common long term health condition affecting children in the UK. According to NHS data, around one in four five year olds in England has experienced decay in at least one tooth. It is also the single leading cause of hospital admissions for children aged five to nine, mostly for tooth extractions under general anaesthetic.
What makes this so frustrating is that almost all of it is preventable. Many children develop their first cavity before they ever sit in a dental chair, which is why the Oral Health Foundation recommends bringing your child for a first dental visit by their first birthday.
A few key factors usually work together to cause cavities. Understanding them is the first step to keeping your child’s smile healthy.
Frequent sugar and starchy snacks: It’s not just how much sugar a child eats, but how often it touches the teeth. Constant grazing on biscuits, raisins, crisps or fruit juice gives bacteria a steady supply of fuel throughout the day.
Sugary drinks and night time bottles: Letting a child fall asleep with a bottle of milk, formula or juice is one of the fastest routes to decay in baby teeth. We’ve explained this in detail in our guide to whether night time milk causes cavities.
Inadequate brushing: Many parents are surprised by how much brushing actually takes. The benchmark is a full two minutes morning and evening using a fluoride toothpaste, and most children still need a parent guiding the brush until around age seven or eight.
Lack of fluoride: Fluoride strengthens enamel and helps reverse very early decay. Children who don’t use a fluoride toothpaste, or who only use a tiny smear that gets rinsed off, are far more likely to develop cavities.
Bacterial transmission: The bacteria that cause decay are passed from caregivers to babies through sharing spoons, dummies and cups. Most parents pass on these bacteria without ever knowing it.
Deep grooves in back teeth: Some children naturally have deeper pits and fissures in their molars, where food and bacteria become easily trapped. These teeth often benefit from a protective sealant.
Decay rarely appears overnight. By the time it hurts, it is usually quite advanced. Catching it early is far easier, cheaper, and spares your child any discomfort. Look out for:
If you notice any of these signs, book a check up sooner rather than later.
Why Tooth Decay in Baby Teeth Still Matters
A common myth is that baby teeth don’t really matter because they fall out anyway. That couldn’t be further from the truth. Baby teeth play a vital role in:
When a baby tooth is lost too early because of decay, surrounding teeth can drift into the empty space, which often leads to crowding and bite problems later on. Untreated decay can also lead to painful infections that can affect the developing adult tooth underneath.
Prevention is far easier than treatment, and most of it comes down to a handful of daily habits.
Brush twice a day with fluoride toothpaste: Make morning and evening brushing non negotiable. Use a fluoride toothpaste, with a thin film for any child under three and a blob the size of a pea from age three onwards. Keep helping until your child can write neatly. Our guide to supervised toothbrushing covers this in more detail.
Limit sugary snacks and drinks: Keep treats to mealtimes rather than spreading them across the day, and stick to water or plain milk between meals.
Avoid the bedtime bottle: Once teeth are present, finish the last feed before bed and follow it with a wipe of the teeth or a quick brush.
Visit the dentist regularly: Most children need a check up every six months, and sometimes more often if they have a higher risk of decay.
Ask about fluoride varnish: A quick, painless application of fluoride varnish two to four times a year can dramatically lower decay risk.
Consider fissure sealants: A thin protective coating applied to the chewing surfaces of back teeth seals out food and bacteria. You can read more in our overview of how fissure sealants protect your child’s teeth.
Choose tooth friendly foods: Cheese, plain yoghurt, vegetables, eggs and whole fruits are kinder to teeth than processed snacks or sugary cereals. The NHS guidance on children’s teeth is a useful starting point for daily routines.
When decay has already taken hold, the right treatment depends on how advanced it is and how old your child is. Common options include:
Fluoride treatment: For very early decay, where the enamel has only just started to weaken, a high strength fluoride varnish can halt the damage and even reverse it.
White fillings: Tooth coloured composite fillings are the most common treatment for cavities that have broken through the enamel. They blend in with the natural tooth and are usually placed in a single visit.
Stainless steel crowns: When a baby tooth has a large cavity that can’t be saved with a filling, a pre fitted silver coloured crown protects the rest of the tooth until it falls out naturally.
Pulpotomy: If decay has reached the nerve of a baby tooth, a pulpotomy removes the infected pulp and seals the tooth, usually followed by a crown to keep it strong.
Extraction: Reserved for badly damaged teeth that can no longer be saved. A space maintainer is often fitted to hold room for the adult tooth.
Sedation or general anaesthetic: For very anxious children, very young children or those who need a lot of work in one go, gentle inhalation sedation or treatment under general anaesthetic may be recommended.
Paediatric dentists are specialists in treating children. We don’t just fix problems when they appear, we work alongside families to stop them happening in the first place. That includes age appropriate brushing advice, dietary support, regular fluoride treatments, sealants and a calm, child friendly environment that helps your child feel safe in the chair. The earlier your child starts visiting a children’s dentist, the more likely they are to grow up without fear and with a strong, healthy set of adult teeth.
At what age should I start brushing my baby’s teeth?
Brushing should begin from the moment that very first tooth pokes through the gum, which is typically somewhere between four and eight months of age.
Can tooth decay in baby teeth be reversed?
Very early decay, sometimes called white spot lesions, can often be reversed with better brushing, less sugar and fluoride treatments. Once a cavity has formed, it needs a filling.
Are white fillings safe for children?
Yes. Modern white composite fillings are widely used for children and are safe, durable and free from mercury. Your dentist will recommend the right type for your child’s individual case.
Is fluoride toothpaste safe for toddlers?
Yes, when used in the right amount. A smear of toothpaste containing at least 1,000 parts per million of fluoride is recommended from the first tooth, increasing to a pea sized amount from age three.
How often should my child see the dentist?
Most children should have a check up every six months. Children at higher risk of decay may need to be seen more often, and your dentist will advise based on your child’s mouth.
Can my child’s diet really affect their teeth that much?
Absolutely. Frequent sugar exposure is the single biggest cause of cavities in children. Cutting back on sugary drinks and grazing makes a significant difference.
If you’re worried about tooth decay in your child, or you’d simply like to make sure you’re doing everything right at home, our friendly paediatric team in Fulham would love to help.
We offer gentle examinations, preventive treatments and tailored advice in a calm, child friendly setting that makes dentistry a positive experience for the whole family. Book a check up with Dr Mali Dental Clinic today and give your child the strongest possible start for a lifetime of healthy smiles.
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