A Brief Guide to the Developmental Stages of Teeth

Raise your hand if you remember one of the first times you lost a tooth.

Maybe it was fairly uneventful—say, your tooth dropped onto the table while your parents were cajoling you into eating your peas. Or maybe your family opted for more fanfare by tying your loose tooth to a doorknob and slamming the door shut. (We NEVER recommend this, by the way!)

In any case, adults know that teeth develop over time, because we’ve all experienced losing our early teeth and growing a permanent set. Here’s a look at what that process is all about.  

Remember, these are just general developmental guidelines, and your child's development may be different. If you ever have any concerns about your child's oral health, please consult directly with their dental healthcare professional.

The Developmental Stages of Teeth

Teeth start to develop in the fetus.

The very basic beginnings of teeth start forming in a fetus around the age of six weeks. After three or four months in the womb, hard tissue forms around the starter teeth.

Children’s teeth generally start to erupt between the ages of six and 12 months.

When a baby is born, they typically have 20 teeth nestled underneath the surface of the gums. These teeth usually start to “erupt” (or protrude through the gums) between the ages of six and 12 months. If you’ve ever cared for a toddler, then you know this is the beginning of the dreaded “teething” stage. Most baby teeth (which are also called “primary” or “deciduous” teeth) erupt by the age of 33 months.

Tooth eruption often follows predictable patterns.

The process of tooth eruption varies from child to child. (For example, the order and/or speed in which teeth come in may vary.) That being said, here are some of the most common patterns that crop up during this process:

• As a general rule, girls’ baby teeth are likely to erupt earlier than boys’.

• Generally, teeth will erupt at a rate of approximately one tooth per month.

• Most commonly, the first tooth to protrude through the gums will be a middle, front tooth on the lower jaw (aka a central incisor).

• Several incisors typically erupt before any molars start to come in.

• Baby teeth usually erupt with space between them, which ensures there’s enough room for larger, permanent teeth to grow in later down the road.

Once all baby teeth have erupted, a child should have 10 visible teeth in the upper jaw and 10 visible teeth in the lower jaw. A child will maintain this complete set of teeth for several years.

Children start to lose their primary teeth around the age of six.

Baby teeth start to fall out in early childhood. Typically, the first teeth to fall out will be central incisors. (You’ll recall that these are also typically the first teeth to erupt.)

As the primary teeth are lost, permanent teeth will start to erupt in order to replace the baby teeth. A child will likely have a mix of baby teeth and permanent teeth in their mouths for several years. As a general rule, kids typically lose their last baby tooth by the age of 12.

Permanent teeth are just that: permanent.

Once all permanent teeth have erupted, these are the teeth you’ll have for the rest of your life (barring the removal of wisdom teeth or other surgical tooth removal). The vast majority of adults possess 32 permanent teeth comprised of a mixture of canines, incisors, premolars, and molars.

It may seem odd that humans lose a set of teeth only to acquire a new one. But it makes sense when you consider that toddler-sized teeth wouldn’t be very effective in an adult-sized jaw. So be glad that your teeth naturally undergo these developmental stages on your behalf—no risky removal techniques required.