When do baby teeth come in? A dentist explains the order and age at which they fall out!

4329900 m Pediatric Dentistry

Last updated July 19, 2022

Human teeth erupt from deciduous teeth to permanent teeth once in life.

Although the age and order of the growth changes vary, there are certain rules.

Knowing this will give you some understanding of whether or not it is appropriate for a child's teeth to fall out at the right time, or if it is OK for them not to fall out.

Why do baby teeth erupt?

When we are children, our teeth change from baby teeth to permanent teeth.

This is called bisexual dentition.

The reason for the bicuspid dentition is that if permanent teeth were to erupt in a child with small jaws, there would be no room for permanent teeth to erupt.

Only after the jaw has grown and there is a firm space for permanent teeth to erupt will permanent teeth erupt.

Mechanism of eruption of permanent teeth from deciduous teeth

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After the baby teeth have erupted, there is a permanent tooth egg in the bone at the end of the root of the baby tooth.

Permanent teeth are first formed after the crown, the head of the tooth, is formed, and then the root of the tooth is formed.

When the roots of the permanent teeth are about half formed, the permanent teeth will erupt.

When permanent teeth erupt, they do so while absorbing the roots of baby teeth.

As the roots of deciduous teeth are gradually absorbed, the deciduous teeth begin to shake.

Shaken baby teeth eventually fall out and permanent teeth erupt.

Teeth erupt, order of eruption


There are a total of 20 baby teeth in the upper and lower teeth, and a total of 32 permanent teeth, including wisdom teeth.

The order in which baby teeth erupt into permanent teeth varies by race, gender, and other factors, but there is a general order in which permanent teeth erupt for Japanese people.

First things first.

Six-year-old molar (first molar)or teeth that grow in further behind the rearmost deciduous tooth called the "tooth" (there are no deciduous teeth here),

The first anterior tooth in the lower jaw (the tooth that grows in is the mandibular central incisor)) will grow back.

Starting with this,

Second anterior tooth in the lower jaw (the tooth that grows in is the mandibular lateral incisor), ,

The first anterior tooth of the upper jaw (the tooth that grows in is the maxillary central incisor), ,

Second anterior tooth in the upper jaw (the tooth that grows in is the maxillary lateral incisor)) grows back,

Eight front teeth and four back teeth in the upper and lower jaws come in permanently.


Thread incisor, the third from the front (the tooth that erupts is the canine), ,

Fourth tooth from the front (the first premolar to erupt), ,

Fifth tooth from the front (second premolar to erupt)will grow back.

The mouth will now be completely free of baby teeth and 24 permanent teeth will be present.

The seventh (second molar) and eighth (wisdom) teeth then erupt in sequence.

Age at which teeth erupt or grow in

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The first molar, the six-year-old molar, as the name implies, often erupts around the age of six,

The central incisor in the lower jaw also often erupts around age 6.

The mandibular lateral incisors, maxillary central incisors, and maxillary lateral incisors erupt at 6 to 7 years of age,

By the age of eight, permanent teeth have erupted in the upper and lower jaws, including eight front teeth and four back teeth.

Between the ages of 8 and 11, the canine teeth, first bicuspids, and second bicuspids replace the deciduous teeth.

By age 12, 24 permanent teeth have erupted,

Eventually, the second molar, the 12-year-old molar, will erupt.

Third molars, the wisdom teeth, vary greatly from person to person and may begin to erupt as early as high school,

In late cases, they may grow back after the age of 25.

Why are teeth hard to pull out or grow back?

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Permanent teeth do not exist

In the absence of permanent teeth, it is unlikely that deciduous teeth will fall out at the appropriate time because root resorption of deciduous teeth does not occur.

The most probable permanent teeth not present are the second anterior tooth and the fifth anterior tooth.

If permanent teeth are not present, the deciduous teeth may be carefully retained, or they may be drastically extracted.

❷ permanent teeth have not erupted normally

If a permanent tooth grows crookedly or does not come out fused to the bone, the root of the deciduous tooth may not be absorbed properly and the deciduous tooth may not come out.

Permanent tooth induction at the appropriate time or orthodontic treatment may be necessary.

❸When growth of the jaw is poor

Poor jaw growth can delay the eruption of permanent teeth because there is not enough space for permanent teeth to erupt, and baby teeth may not erupt.

Orthodontic treatment, such as floor orthodontics, is needed to stimulate jaw growth.

If the ❹ bone has a birthmark in it

A growth in the bone can inhibit the eruption of permanent teeth.

Thus, baby teeth do not fall out at the appropriate time. Especially common during childhood is a benign tumor called odontoma.

If a odontoma is present, it should be removed by a dentist who can handle it.


The teething period is often a time of anxiety because of the many changes in the mouth.

If you are concerned that your child's teeth are coming out earlier than they should, or if they are not coming out when they should, see your dentist.

imageWritten by dentist/issy

After graduating from the National School of Dentistry, he trained at the Tokyo Medical and Dental University Dental Hospital, and is currently working in general and orthodontic dentistry.

Member of the Japanese Society of Oral Implantology


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