How many teeth are in an adult's mouth?
A fully grown adult usually has 32 permanent teeth, divided evenly between the upper and lower jaw, 16 in each. A common question is how many teeth humans have and what counts as normal, especially since wisdom teeth do not erupt in everyone.
| Type of tooth | Number in each jaw |
|---|---|
| Incisors | 4 |
| Canines | 2 |
| Premolars | 4 |
| Molars | 6, including 2 wisdom teeth |
| Total | 16 (32 in both jaws) |
The wisdom teeth, one on each side of each jaw, usually erupt between ages 17 and 21. The actual number of teeth varies with genetics and anatomy: some wisdom teeth never develop or stay buried in the jawbone.
32
Permanent teeth in a complete adult set
The number of teeth in the mouth is divided into four quarters of 8 teeth. In the FDI numbering system used in Israel, the upper right quarter is 1, upper left 2, lower left 3 and lower right 4; in the United States, the Universal system numbers teeth 1 to 32.
How many teeth are in the upper jaw and the lower jaw?
The upper jaw (maxilla) has 16 permanent teeth in an adult, exactly like the lower jaw (mandible).
Each jaw is divided into two identical halves, and each half has 8 teeth: 2 incisors, 1 canine, 2 premolars and 3 molars. Although both jaws have the same number of teeth, they differ: the upper teeth sit in the maxilla, a fixed bone that is part of the facial skeleton, while the lower teeth sit in the mandible, a movable bone connected to the skull by the jaw joint (TMJ). This difference affects wear patterns and the forces the teeth receive during chewing and speaking.
How teeth grow from childhood to adulthood
Teeth develop in two sets: baby teeth, which start to appear around 6 months, and permanent teeth, which start to erupt around age 6.
Baby teeth
Children have 20 baby teeth, 10 in each jaw. They erupt in a fairly predictable order, starting with the lower central incisors, and all 20 are usually present by about age 3. See how many teeth children have.
The changeover
Around age 6, the first permanent molar erupts behind the baby teeth without replacing any of them. Between about 6 and 12, baby and permanent teeth are present together (mixed dentition), a period when dental follow-up checks that permanent teeth come in the right place.
Second molars and wisdom teeth
Second molars erupt around age 11 to 13, so at that age there are usually 28 permanent teeth. Wisdom teeth, the third molars, usually erupt between 17 and 21 and sometimes remain impacted or come in at an angle.
Examination, treatment plan and price quote
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During the consultation, Dr Haim Aseriel examines your teeth, explains all the options and gives you a transparent price quote, with no obligation. The clinic is at 12 HaTnufa Street, Jerusalem.
Wisdom teeth: necessary or not?
Wisdom teeth are often described as evolutionary leftovers: as human diets became softer, jaws became smaller, but the third molars remained.
Problem wisdom teeth can cause gum infection around a partly erupted tooth (pericoronitis), pressure on neighboring teeth, decay in the wisdom tooth or the second molar next to it, and deep gum pockets.
According to a worldwide meta-analysis, about 23% of people have at least one wisdom tooth that never develops (agenesis), with large differences between populations (Carter & Worthington, 2015).
A healthy wisdom tooth can sometimes be useful, for example as an anchor for a dental bridge when another molar is lost. The decision on wisdom teeth removal is made after an examination and X-ray, not on age alone. For impacted wisdom teeth that cause no symptoms or disease, a Cochrane review found insufficient evidence for or against preventive removal (Ghaeminia et al., 2020); when removal is needed, it is usually simpler in young adults.
The different types of teeth
Permanent teeth fall into four groups by shape and function: incisors, canines, premolars and molars. The 8 incisors at the front (central and lateral) are flat and sharp for cutting. The 4 canines (cuspids), one in each quarter, are the most pointed teeth and have the longest roots. The 8 premolars, right behind the canines, have two cusps and start crushing food. The 12 molars (8 without wisdom teeth) are the largest and strongest, with 4 to 5 cusps; the first permanent molar, which erupts around age 6, plays a key role in how the teeth fit together.
| Type of tooth | Number in the mouth | Function |
|---|---|---|
| Incisors | 8 | Cutting food |
| Canines | 4 | Tearing food |
| Premolars | 8 | Crushing and first grinding |
| Molars | 12 (8 without wisdom teeth) | Grinding |
For a closer look at the parts and layers of each tooth, see tooth anatomy.
Why do people lose teeth, and how many teeth does the average adult have?
Although 32 is the full set, the real average is lower: according to NIDCR data from the United States (2017 to 2020), adults aged 20 to 64 had an average of 26 remaining teeth, and adults aged 50 to 64 about 23.
01
Gum disease
Gum disease (periodontitis) is one of the main causes of tooth loss in adults: a chronic inflammation that destroys the gums, ligament and bone that hold the tooth.
02
Decay and injuries
Tooth decay left untreated can lead to infection and, eventually, extraction. Injuries from accidents, contact sports or falls cause tooth loss especially in children and teenagers. If a permanent tooth is knocked out, act quickly and see a dentist immediately; what to do with the tooth until then is explained in the FAQ below.
03
General health and medications
Uncontrolled diabetes raises the risk of gum disease and tooth loss, and some osteoporosis medications can cause jawbone necrosis. According to the CDC, smokers have twice the risk of gum disease. Most tooth loss is preventable with good hygiene, regular check-ups and early treatment.
Missing teeth: consultation in Jerusalem, in English
When teeth are missing, options such as dental implants, bridges or dentures can restore chewing and appearance. Dr Haim Aseriel, a US-trained dentist (DDS, NYU College of Dentistry; B.A. in Biology, Yeshiva University), examines your mouth, explains the options in English and gives you a written plan and estimate. The clinic is at 12 HaTnufa Street in Talpiot, south Jerusalem, open Sun 8:00–19:00 · Mon 9:00–19:00 · Tue–Wed 9:00–21:00 · Thu 8:30–21:00 · Fri 8:00–14:00.
How many teeth do humans have: frequently asked questions
Yes. In many people some wisdom teeth never develop, or stay impacted in the bone and are not visible in the mouth, so 28 teeth is also normal. An X-ray at the dentist shows whether there are impacted wisdom teeth and whether they need monitoring.
Each jaw, upper and lower, has 16 permanent teeth. Each half-jaw, right or left, has 8 teeth: 2 incisors, 1 canine, 2 premolars and 3 molars, the last of which is the wisdom tooth.
Wisdom teeth usually erupt between ages 17 and 21. The decision to remove them is based on an examination and X-ray, not on age alone: a wisdom tooth causing infection, decay or damage to the neighboring tooth is treated, while for impacted wisdom teeth without symptoms a Cochrane review found insufficient evidence for or against preventive removal.
When a permanent tooth is missing, check with your dentist the options for replacing it, such as a dental implant, a bridge or a removable denture. After a tooth is lost, the bone in the area gradually shrinks and the neighboring teeth may drift into the gap, so it is best not to postpone the examination.
Hold the knocked-out permanent tooth by the crown only, never the root, rinse it gently with water if it is dirty and try to put it back in its socket right away. If that is not possible, keep it in milk or in the mouth against the cheek (not in water) and see a dentist immediately, ideally within 30 minutes. A knocked-out baby tooth should not be put back, but the child should see a dentist.
Sources
- American Dental Association (MouthHealthy), Eruption Charts – View the page
- American Dental Association, Permanent Tooth Development, 2012 – View the document
- American Dental Association (MouthHealthy), Wisdom Teeth – View the page
- Carter K & Worthington S, Journal of Dental Research, 2015 – View the study
- Ghaeminia H et al., Cochrane Database of Systematic Reviews, 2020 – View the study
- National Institute of Dental and Craniofacial Research (NIH), Tooth Loss in Adults (Ages 20 to 64) – View the page
- Centers for Disease Control and Prevention, Smoking, Gum Disease, and Tooth Loss – View the page
- American Association of Endodontists, Knocked Out Teeth – View the page
- Fouad AF et al., Dental Traumatology, 2020 – View the study
- Day PF et al., Dental Traumatology, 2020 – View the study
