Quick answer: Adults usually have 32 permanent teeth—8 incisors, 4 canines, 8 premolars, and 12 molars when all four wisdom teeth are present. Children normally have 20 primary (baby) teeth: 8 incisors, 4 canines, and 8 molars. Each group has a different shape and job.
Dentally reviewed by Dr. Manish Pandey, BDS, FAGE (Manipal University)
Last reviewed: 13 August 2026
Human teeth diagram: names and positions
The mouth is divided into four quadrants: upper right, upper left, lower left, and lower right. In a complete adult dentition, each quadrant contains the same eight teeth, starting at the centre and moving toward the back.
| Front to back in each adult quadrant | Common name | Main function |
|---|---|---|
| 1 | Central incisor | Cutting food |
| 2 | Lateral incisor | Cutting and guiding food |
| 3 | Canine (cuspid) | Gripping and tearing |
| 4 | First premolar | Crushing and grinding |
| 5 | Second premolar | Crushing and grinding |
| 6 | First molar | Heavy chewing and grinding |
| 7 | Second molar | Chewing and grinding |
| 8 | Third molar (wisdom tooth) | Chewing, when present and functional |
This repeated pattern gives the adult dental formula 2 incisors, 1 canine, 2 premolars, and 3 molars per quadrant. A person may have fewer than 32 teeth if wisdom teeth never developed, have not erupted, or were removed.
The four types of teeth and what they do
Incisors
Incisors are the eight teeth at the front of an adult or child’s mouth—four upper and four lower. Their relatively thin edges bite into and cut food. The two teeth beside the midline are central incisors; the teeth immediately beside them are lateral incisors. Incisors also help support the lips and contribute to clear speech and the appearance of a smile.
Canines
The four canines sit between the incisors and premolars. They are sometimes called cuspids because each usually has one prominent cusp, or pointed tip. Their strong roots and pointed crowns help grip and tear food. Canines also help guide the jaws during side-to-side movement, protecting some of the back teeth from excessive forces.
Premolars
Adults normally have eight premolars, also called bicuspids, with two in each quadrant. They sit behind the canines and in front of the molars. Their broader chewing surfaces crush and grind food. Primary dentition has no premolars: permanent premolars replace the primary molars when a child’s adult teeth develop.
Molars
Molars are the large back teeth with broad surfaces and several cusps. They do most of the heavy crushing and grinding. A complete adult mouth has 12 molars: first, second, and third molars in each quadrant. The third molars are the wisdom teeth. Children have eight primary molars—two in each quadrant.
Baby teeth vs. permanent teeth
| Feature | Primary (baby) teeth | Permanent (adult) teeth |
|---|---|---|
| Usual total | 20 | 32 including four wisdom teeth; often 28 without them |
| Types | Incisors, canines, molars | Incisors, canines, premolars, molars |
| First teeth commonly appear | Around 6 months, with normal variation | First molars and lower central incisors often appear around age 6 |
| Typical completion | By about age 3 | Most teeth by early adolescence; wisdom teeth vary |
Baby teeth are not disposable placeholders. They allow chewing and speech, maintain space for permanent teeth, and help guide the developing adult teeth. Tooth decay or early loss of a baby tooth can affect comfort, nutrition, and spacing, so children’s teeth need the same daily attention as adult teeth.
Parts of a tooth
- Crown: the portion normally visible above the gumline.
- Root: the portion anchored in the jawbone beneath the gum.
- Enamel: the highly mineralized protective outer covering of the crown. It cannot grow back after being lost, although early mineral loss may sometimes be reversed with fluoride and good plaque control.
- Dentin: the hard tissue beneath enamel and cementum. Tiny tubules in dentin can transmit sensations when it becomes exposed.
- Pulp: the soft central tissue containing nerves, blood vessels, and connective tissue.
- Cementum: the calcified tissue covering the root surface.
- Periodontal ligament: fibres that connect the root’s cementum to the surrounding socket and help absorb chewing forces.
Tooth numbering systems
Dentists use numbers or letters to identify a tooth precisely. In the Universal system, commonly used in the United States, permanent teeth are numbered 1 through 32. Number 1 is the upper-right wisdom tooth; the count travels across the upper arch to number 16, then continues from the lower-left wisdom tooth (17) to the lower-right wisdom tooth (32). Primary teeth are labelled A through T.
The FDI two-digit system is widely used internationally. The first digit identifies the quadrant and the second identifies the tooth’s position from the centre. For example, 11 is the upper-right central incisor and 36 is the lower-left first permanent molar. Your dentist may use a different system depending on the country and clinical software.
When do teeth erupt?
Eruption ages are approximate ranges, not deadlines. Genetics and individual development can shift the schedule. Primary teeth commonly begin with the lower central incisors around 6 to 10 months and most children have all 20 by about age 3. Permanent first molars and lower central incisors often erupt near age 6. Most permanent teeth other than wisdom teeth are present by the early teenage years.
| Permanent tooth group | Common eruption range |
|---|---|
| First molars | About 5½–7 years |
| Central incisors | About 6–8 years |
| Lateral incisors | About 7–9 years |
| Canines | About 9–12 years |
| Premolars | About 10–13 years |
| Second molars | About 12–14 years |
| Third molars | Highly variable; often 17–30 years if they erupt |
A dentist should assess a tooth that is very delayed, erupts in an unusual position, causes persistent pain, or appears to have no room. An examination—and sometimes an X-ray—can distinguish normal variation from a missing, impacted, or displaced tooth.
Wisdom teeth: do they always need removal?
No. A healthy, fully erupted wisdom tooth that is painless, functional, and easy to clean may not need removal. Problems are more likely when a wisdom tooth is trapped under gum or bone, partly erupted, decayed, infected, damaging a neighbouring tooth, or associated with a cyst. Pain or swelling near the back of the jaw deserves a dental examination; removal decisions should be based on symptoms, position, disease risk, and imaging rather than age alone.
How to keep every type of tooth healthy
- Brush twice daily for two minutes with fluoride toothpaste.
- Clean between the teeth daily with floss or another interdental cleaner that suits the space.
- Limit how frequently teeth are exposed to sugary foods and drinks.
- Do not use teeth to open packages or bite hard objects.
- Attend dental check-ups at intervals recommended for your individual risk.
- Seek care for pain, swelling, a broken tooth, persistent sensitivity, bleeding gums, or a tooth that becomes loose unexpectedly.
For practical prevention advice, read how to prevent cavities and our guide to tooth enamel and how it withstands daily use.
Frequently asked questions
How many teeth do adults have?
Up to 32 permanent teeth, including four wisdom teeth. Many healthy adults have 28 because their wisdom teeth are absent, unerupted, or removed.
How many teeth do children have?
A complete primary dentition has 20 teeth: 10 in the upper jaw and 10 in the lower jaw.
Which teeth are used for chewing?
Premolars and molars do most crushing and grinding. Incisors cut food and canines help grip and tear it before the back teeth process it further.
Are bicuspids and premolars the same?
Yes. “Bicuspid” is a common older name for a premolar, although not every premolar has exactly two cusps.
Key takeaway
Tooth names describe both position and function: incisors cut, canines grip and tear, premolars crush, and molars grind. Knowing the basic map makes dental charts and treatment discussions easier to understand, but tooth counts and eruption timing naturally vary. A dentist can confirm whether an unusual-looking, missing, painful, or delayed tooth needs attention.
This article is for general education and does not replace an examination or personalised advice from a dentist.