Children develop 20 primary teeth, sometimes called baby teeth or deciduous teeth. These 20 teeth include eight incisors, four canines, and eight molars, evenly split between the upper and lower jaws. They start appearing around 6 months of age and are typically all in place by age 3.
The 20 Primary Teeth by Type
Each jaw (upper and lower) holds 10 primary teeth, arranged symmetrically on the left and right sides. Here’s how they break down:
- Incisors (8 total): Four on top, four on bottom. These are the flat front teeth used for biting into food. Each jaw has two central incisors in the middle and two lateral incisors flanking them.
- Canines (4 total): Two on top, two on bottom. These are the pointed teeth next to the incisors, used for tearing food.
- Molars (8 total): Four on top, four on bottom. Each side of each jaw has a first molar and a second molar. These broader, flatter teeth handle chewing and grinding.
Unlike the adult set of 32 permanent teeth, primary teeth don’t include premolars or third molars (wisdom teeth). The smaller count matches a child’s smaller jaw.
When Each Tooth Appears
The lower central incisors are usually the first to show up, breaking through the gums between 6 and 10 months. The upper central incisors follow shortly after, typically between 8 and 12 months. From there, teeth tend to arrive in rough pairs, working from the front of the mouth toward the back.
Lateral incisors come in around 9 to 16 months, followed by the first molars between 13 and 19 months. The canines fill in the gap between the incisors and molars around 16 to 23 months. The second molars arrive last, usually between 23 and 33 months. By around age 3, most children have all 20 primary teeth in place.
These ranges are averages. Some babies cut their first tooth at 4 months, while others don’t see one until closer to their first birthday. The timing varies widely and isn’t a sign of a problem in either direction.
Why Primary Teeth Matter
It’s easy to dismiss baby teeth because they’ll eventually fall out, but they serve several functions that affect long-term dental health. Primary teeth act as placeholders, holding space in the jaw for the permanent teeth developing beneath them. When a baby tooth is lost too early from decay or injury, neighboring teeth can drift into the gap and block the permanent tooth from coming in straight. This is one of the most common reasons children end up needing orthodontic treatment later.
Primary teeth also play a direct role in shaping the jaw and facial structure as a child grows. They contribute to the natural widening of the jaw that creates room for the larger permanent teeth. Beyond structure, children rely on these teeth for learning to chew solid foods and for speech development, particularly sounds that require the tongue to press against the teeth.
How Primary Teeth Differ From Adult Teeth
Primary teeth are noticeably smaller and whiter than permanent teeth. They also have thinner enamel, averaging about 0.5 mm compared to 1.0 mm or more on a permanent tooth. This thinner protective layer is why cavities in baby teeth can progress quickly and reach the nerve faster than they would in an adult tooth. The pulp chamber (the inner area containing nerves and blood vessels) is also proportionally larger in primary teeth, which compounds the problem.
This is worth keeping in mind for parents who assume cavities in baby teeth don’t need attention. A small cavity can become a painful infection relatively fast in a primary tooth.
When Primary Teeth Fall Out
Children generally start losing their baby teeth around age 6 and finish around age 12 or 13. The teeth tend to fall out in roughly the same order they arrived, starting with the lower central incisors.
Here’s the typical shedding timeline:
- Central incisors: 6 to 8 years
- Lateral incisors: 7 to 9 years
- First molars: 9 to 12 years
- Canines: 9 to 12 years
- Second molars: 9 to 13 years
Lower teeth usually shed slightly earlier than their upper counterparts. During this transition period, children have a mix of primary and permanent teeth, sometimes called “mixed dentition.” It’s normal for new permanent teeth to look larger and more yellow next to the remaining baby teeth.
When the Count Is Off
Not every child ends up with exactly 20. Some are born with a tendency to develop extra teeth, a condition called hyperdontia, while others develop fewer teeth than expected, called hypodontia. Both are uncommon in the primary set. Hyperdontia affects roughly 0.6% of primary teeth, making it far less common in baby teeth than in the permanent set, where it occurs in up to 3.8% of cases.
Missing or extra primary teeth are typically spotted on dental X-rays. A missing baby tooth can sometimes signal that the corresponding permanent tooth is also absent, so your child’s dentist may want to monitor the area as the jaw develops.