What causes tooth decay in babies and toddlers?

David W. Zirlin, DMD
Pediatric Dentistry
The same way adult teeth decay. There are bacteria in the mouth, we eat sugars and as these bacteria digest the sugars they let off a waste product of acid, which demineralizes the enamel and breaks down the tooth.
Todd A. Welch, DMD
Your child's baby teeth are important. Children need strong, healthy teeth to chew their food, speak and have a good-looking smile. Baby teeth also keep a space in the jaw for the adult teeth. If a baby tooth is lost too early, the teeth beside it may drift into the empty space. When it's time for the adult teeth to come in, there may not be enough room. This can make the teeth crooked or crowded. Starting infants off with good oral care can help protect their teeth for decades to come.

The tooth decay is almost completely preventable. You can help prevent tooth decay for your child by following the tips below:
  • Lower the risk of the baby’s infection with decay-causing bacteria. This can be done two ways, by improving the oral health of the mother/caregiver which reduces the number of bacteria in her mouth and by not sharing saliva with the baby through common use of feeding spoons or licking pacifiers and giving them to babies.
  • After each feeding wipe the baby’s gums with a clean, damp gauze pad or washcloth. This will remove plaque and bits of food that can harm erupting teeth. When your child’s teeth begin to erupt, brush them gently with a child’s size toothbrush and water. (Consult with your child’s dentist or physician if you are considering using fluoride toothpaste before age two.)
  • When your child can be counted on to spit and not swallow toothpaste (usually not before age two), begin brushing the teeth with a pea-sized amount of toothpaste. The American Dental Association recommends fluoride toothpaste; ask your dentist about your child’s fluoride needs.
  • Brush your child’s teeth until he or she is at least six years old.
  • Place only formula, milk or breastmilk in bottles. Avoid filling bottles with liquids such as sugar water, juice or soft drinks.
  • Infants should finish their bottles before going to bed.
  • If your child uses a pacifier provide one that is clean; don’t dip it in sugar or honey, or put it in your mouth before giving it to the child.
  • Encourage children to drink from a cup by their first birthday and discourage frequent or prolonged use of a training (sippy) cup.
  • Encourage healthy eating habits that include a diet with plenty of vegetables, fruit and whole grains. Serve nutritious snacks and limit sweets to mealtimes.
  • Ensure that your child has adequate exposure to fluoride. Discuss your child’s fluoride needs with your dentist or pediatrician.
Some of the "ingredients" for tooth decay depend on
  • Time of contact of acids and sugars on the teeth
  • Strep (or other bacteria that can cause decay)
  • Food for the bacteria (sugars)
  • Waste products (acids) secreted by the bacteria 
If you are able to disrupt the above "ingredients" there is a lower chance of decay forming.

This is why a child shouldn't go to sleep with a bottle of juice. Sugar sits on the tooth all night, allowing the bacteria to digest it and produce acids that damage teeth.
Tooth decay is a disease that begins with cavity-causing bacteria being passed from the mother (or primary caregiver) who has these bacteria in their mouth to the infant. These bacteria are passed through the saliva. When the mother puts the baby's feeding spoon in her mouth or cleans a pacifier in her mouth, the bacteria are passed to the baby.

Another factor for tooth decay is the frequent, prolonged exposure of the baby's teeth to liquids that contain sugar, like sweetened water and fruit juice and potentially milk, breast milk and formula. Tooth decay can occur when the baby is put to bed with a bottle, or when a bottle is used as a pacifier for a fussy baby. The sugary liquids pool around the teeth while the child sleeps. Bacteria in the mouth use these sugars as food. They then produce acids that attack the teeth. Each time your child drinks these liquids, acids attack for 20 minutes or longer. After multiple attacks, the teeth can decay.

Pacifiers dipped in sugar or honey can also lead to tooth decay since the sugar or honey can provide food for the bacteria's acid attacks.

Infants and toddlers who do not receive an adequate amount of fluoride may also have an increased risk for tooth decay since fluoride combines with the outer covering of the tooth (enamel) and makes the tooth more resistant to the acid attack.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.