Tooth decay in children: Causes, signs, and prevention

Last Updated July 2022

Tooth decay is the most common oral disease affecting young people in England. In fact, just under a quarter of five-year-olds in England have tooth decay (also known as dental caries or cavities). When left untreated, tooth decay can cause discomfort and nasty infections. The good news is there are several ways to prevent it, with almost nine out of 10 hospital tooth extractions for children up to five years old being preventable.

In this article, we’ll explore some of the common causes of tooth decay in children, and how to treat it. We’ll also look at how building good oral hygiene habits early on can help prevent tooth decay in children

Signs of tooth decay in children

The signs of tooth decay can vary from child to child. Sometimes a child may not experience any signs, especially if it’s still in the early stages. Other times, the signs can be more obvious. When brushing your child’s teeth, it’s a good idea to examine them. This way, you’ll be able to spot any changes.

Here are some of the most common concerns to look out for:

White spots forming on the tooth

White spots on the teeth could signify tooth decay. They appear as a different shade of white to the rest of the teeth. These spots develop when the outer surface of the teeth (the enamel) is damaged.

Sensitivity or pain to hot, cold, or sweet foods

Sensitivity to hot, cold, and sweet foods can happen when the tooth’s outer protective layer of enamel has worn down . When the enamel wears away, it exposes the sensitive layer of the tooth, known as dentine. The dentine contains tiny holes which connect the nerves inside the teeth. Once the dentine is exposed, food and drink can make their way to the tooth’s nervous centre, causing pain or tooth sensitivity.

The tooth is darkening in colour

Teeth appear a shade of white due to the calcium present in enamel. However, when the enamel starts to thin, this causes the underlying layer (the dentine) to be exposed. This makes the teeth appear darker in colour.

A hole is forming in the tooth

Plaque and bacteria can tear away at the enamel, leaving a small hole behind.

If you notice your child is experiencing any of the above symptoms, you should get advice from a dentist.

If your child is experiencing any of the following symptoms, you should get immediate medical attention:

  • Severe pain
  • Swelling of gums
  • Pus from the tooth
  • Problems eating
  • Signs of a fever or infection.

Causes of tooth decay in children

Poor oral hygiene

Oral health is an essential part of our overall well-being. Poor oral hygiene can result in a build-up of plaque on the teeth. Plaque is a sticky-like substance covering the teeth and develops when bacteria in the mouth is mixed with food and saliva. This build-up of plaque can quickly lead to cavities.

It’s important to teach children how to floss and brush properly from a young age and make sure they’re using fluoride toothpaste, as this can help prevent tooth decay. However, children under the age of two should avoid fluoride toothpaste unless approved by a doctor or dentist. Regular flossing can also help remove plaque from your child’s teeth.

High sugar diets

Diet plays a huge role in oral health. Often, children have a diet containing too many sugars and starches, which can put them at risk of tooth decay. The molecules in sugary foods, such as fizzy drinks, sweets, and cakes become acidic from the bacteria in their mouth. Over time, the acid breaks down the tooth enamel, causing cavities.

Try making swaps to sugar-free drinks and low-fat milk and steer clear of ‘healthy’ sugars such as honey and syrup. These often contain large quantities of sugar and can be just as problematic for children’s teeth.

A dry mouth

A dry mouth or low saliva production can put your child at risk of tooth decay. This is because the primary function of saliva is to wash away food debris in the mouth. Saliva also has properties that can directly fight the bacteria that cause tooth decay.

Prolonged bottle-feeding

Prolonged bottle-feeding can lead to baby bottle tooth decay, also known as early childhood caries (ECC) . Baby bottle tooth decay typically affects the front teeth, but other teeth may also become damaged. A common cause of baby bottle tooth decay is when a child is put to bed with a bottle that contains a sweetened liquid.

How to prevent tooth decay in children

Thankfully, there are plenty of ways you can help to prevent tooth decay in children.

Teach good brushing habits early

Teaching children how to floss and brush correctly from a young age is essential. It can reduce the early signs of child tooth decay and help them stick to a regular brushing routine when they’re older.

Children up to three years:

  • Brush your baby’s teeth as soon as their first milk tooth appears.
  • Always supervise your child when brushing.
  • Use a smear of toothpaste.
  • Brush twice a day for around two minutes.

Children aged three to six years:

  • Brush twice a day for two minutes with fluoride toothpaste.
  • Use a pea-sized amount of toothpaste.
  • Supervise your child while brushing.

Children aged seven years and over:

  • Brush twice daily for two minutes with fluoride toothpaste.
  • Children should be able to brush their teeth independently at this age, but it’s a good idea to keep an eye on them to make sure they’re brushing correctly.

Feed them tooth-friendly items

While avoiding sugary foods can prevent cavities, there are also certain foods your child can eat to help lower their risk of tooth decay. Foods that are rich in calcium, Vitamin C, and protein can help prevent cavities forming.

These include:

  • Eggs – naturally rich in Vitamin D, an essential nutrient that makes the teeth stronger.
  • Yoghurt – is loaded with calcium.
  • Cheese – is a good source of calcium.
  • Salmon – a superfood packed with Vitamin D and calcium.
  • Apples – contain natural sugars which can help neutralise harmful acids.

Pick fun brushes and child-friendly flavours

Make toothbrushing fun with colourful toothbrushes and toothpaste. Many children don’t enjoy brushing their teeth, and it can often be a battle for parents to get them to do so. These days you can find all sorts of kid-friendly brushes in bright colours and covered with their favourite movie and TV show characters. Various toothpaste flavours appeal directly to children, including bubble gum, strawberry, and chocolate.

Make brushing fun

There are plenty of ways you can add some extra fun to your child’s oral care routine:

Play a song

There’s no rule that you must brush your teeth in silence. So, why not play an upbeat song for your child while they brush, floss, and rinse their teeth? Try and select a song that’s at least two minutes long and encourage your child to keep brushing until the song finishes.

Create a tooth brushing chart

Create a tooth-brushing chart to encourage your children to brush their teeth. Each time they brush their teeth, reward them with a gold star. After 14 days of twice-daily brushing, treat them to a toy they want or surprise them with enticing prizes.

Tell a story

Highlight the importance of tooth brushing through an animated story. Refer to the sugar that can cause tooth cavities as ‘sugar bugs’ and turn your child into a superhero, complete with a cape, who fights off those sugar bugs in their mouth, attacking their teeth with toothpaste.

Schedule regular trips to the dentist

Scheduling regular check-ups at the dentist is important, as it means the first symptoms of tooth decay can be spotted and treated early. Frequent visits to the dentist can also teach children the importance of good oral hygiene.

Treatment options for children with tooth decay

If the issue of your child’s tooth decay has progressed, your dentist may recommend dental treatments to resolve the problem. These could include:

Fissure sealant

Fissure sealants are plastic coatings painted onto the grooves of the back teeth. They form a protective layer over the teeth to prevent food and bacteria from getting stuck. They typically last for several years but may need replacing as they can wear over time.

Fluoride varnish

Fluoride varnish is a dental treatment that can help prevent and slow down tooth decay. The pale yellow, gel-like substance is applied with a soft brush and is left to set on the teeth. Once set, it can act as an extra layer of protection against tooth decay.


Fillings are one of the most common dental procedures. The procedure is carried out at the dentist and can take as little as 20 minutes. Children under the age of five may require general anaesthesia but your dentist will let you know if that’s the case. During the procedure, the dentist will remove the infected decay in the tooth and fill the area with a filling or a crown. This can help prevent further decay and enable the tooth to function properly.


If the tooth is too damaged or decayed to be repaired with a filling or crown, a total extraction may be necessary. This involves removing the damaged tooth to prevent the spread of infection.