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How often do teeth grow in?

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HealthWiki > Where There Is No Dentist > Chapter 4: School Activities for Learning about Teeth and Gums > How often do teeth grow in?

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A child gets two sets of teeth. The first set, baby teeth, starts to grow when the child is a baby. The second and last set grows in at school age. They are the permanent teeth. Permanent teeth should last a lifetime.

A child grows his first baby tooth at about 7 months of age. It is usually a front one.

A baby who is poorly nourished, however, may not grow his first tooth until later. Do not wait for the first tooth before giving him the extra soft food he needs to grow and stay healthy.

The remaining baby teeth grow in over the next 24 months. By the time the child is 30 months old, there will be a total of 20 baby teeth in his mouth, 10 on top and 10 on the bottom.

Most permanent teeth form under the baby teeth. When the child is between 6 and 12 years old, the permanent teeth push against the roots of the baby teeth, making them fall out. Not all of the baby teeth fall out at once. One tooth at a time becomes loose, falls out, and then is replaced with a permanent tooth. The new tooth may not grow in immediately. Sometimes 2 or 3 months pass before the new tooth grows into the space.

In the 6 years between ages 6 and 12, the 20 permanent teeth replace the 20 baby teeth. In addition, 8 other teeth grow in behind the baby teeth.

the 32 permanent teeth, including 4 sets of 3 molars at the back.
16 teeth
on top
16 teeth
on the
3rd molar
2nd molar
1st molar

At 6 years, the 4 first permanent molars start to grow in at the back of the mouth. This means an 8-year-old child should have 24 teeth, or spaces for them.

At 12 years, the 4 second permanent molars grow in behind the first molars. This means a 14-year-old child should have 28 teeth, or spaces for them.

Between 16 and 22 years, the 4 third permanent molars grow in. This means that an adult usually has a total of 32 permanent teeth: 16 on top and 16 on the bottom.

(Note: The third molars often do not grow in correctly. This is a very common cause of tooth pain.)


Have the students examine each other.Help them learn which are baby teeth and which are permanent teeth. Look for the important 1st permanent molars at the back. Here the children are only counting the teeth. They can also learn to check for cavities and gum disease.

a child's mouth
permanent tooth
loose baby tooth
space for new tooth

Show the students how to count the teeth and the spaces that are ready for new teeth to grow in.

Then have them count their friends’ teeth, to find out how many teeth should be growing in different age groups. Later, they can do this with their brothers and sisters at home.

  • Wash your hands.
  • Count the teeth.
  • Count the spaces where new teeth have not yet grown in.
TOTAL = teeth + spaces
  • Find out the person’s age.

Have the students first write their totals on the blackboard. Then make a chart for the children to remember and discuss the results.

numbers of teeth and spaces of students of different ages.

Discuss the number of teeth children have at different ages. Young children 6 to 12 years old, for example, have 24 teeth; older students, 28 teeth; and most adults, 32 teeth.

At home, students can count brothers’ and sisters’ teeth to learn how many teeth small children have. Count only the teeth and not the spaces.

numbers of teeth of children under 3.

Ask the students what other things they saw inside someone else’s mouth. This is a good time for students to discover important things about good health practices. Encourage them to learn as much as they can from what they see, and then show them how to use a book like this to answer their own questions, For example, if students see cavities and red bleeding gums, you can start a discussion on tooth decay and gum disease. See about some of the activities you can use.

For another example, if the students see a baby who has only a few teeth, they may have some interesting questions. Invite them to read about baby teeth to find answers to questions like these.

  • Can Chenia, who is 6 months old and has no teeth, eat soft foods? Should she have more than just breast milk?
  • When Chenia’s teeth grow in, will they give her diarrhea and fever?
  • Will a 2-year-old girl get more baby teeth?
  • Why do we care for baby teeth, when we only need them for a few years?

This page was updated:19 Feb 2018