How many teeth does an adult have, and how many does a child have?

How many teeth does an adult have?

A full adult set is 32 teeth: 16 in the upper jaw and 16 in the lower. That count includes the four wisdom teeth (third molars), which are the last to arrive, usually between 17 and 25. Because wisdom teeth are so often missing, impacted or removed, the practical answer for many Australian adults is 28. Having 28 functioning teeth is completely normal and nothing is lost by it.

Each side of each jaw has the same line-up, working from the front: two incisors, one canine, two premolars and three molars (the third being the wisdom tooth). That gives eight incisors, four canines, eight premolars and twelve molars across the mouth. The upper and lower sets mirror each other so that teeth meet their opposite number when you bite.

The average adult has all 32 by about age 21, according to Victoria’s Better Health Channel, “including wisdom teeth”, with the note that some people only ever have 28 because the wisdom teeth do not develop or do not come through. A smaller number of people are born missing other teeth (most often the upper lateral incisors or second premolars), and a few grow extra, or supernumerary, teeth. Both are things a dentist picks up on x-rays and can plan around.

How many teeth does a child have?

A child has 20 baby teeth (also called primary, milk or deciduous teeth): 10 on top and 10 on the bottom. The set is smaller because a child’s jaw is smaller, and it has no premolars at all. On each side of each jaw there are two incisors, one canine and two molars. The full set is usually in place by about age three.

The baby teeth are not just placeholders. They let a child chew and speak properly, and each one holds a space in the jaw for the adult tooth developing beneath it. Lose a baby molar early to decay and the neighbouring teeth can drift into the gap, leaving too little room for the adult tooth later. That is one reason dentists treat decay in baby teeth rather than simply pulling them. Our baby teeth guide has the full eruption chart.

The mixed-dentition years: 6 to 12

Between about six and twelve, children have a mixture of baby and adult teeth, which is why the count is confusing in this age group. The first adult teeth to appear are usually the first molars, which come in behind the last baby molars at around six without replacing anything, and the lower central incisors, which replace the baby ones at about the same time. A six-year-old therefore briefly has 24 teeth.

From there the baby teeth loosen and fall out in roughly the order they arrived, and adult teeth replace them. The baby molars are replaced by adult premolars at about 9 to 12, the canines at 9 to 13, and the adult second molars come through behind at 11 to 13. By about 12 or 13 most children have 28 adult teeth, and the only ones still to come are the wisdom teeth, years later.

This is also the window when orthodontists like to see children for a first assessment, usually around age 7 to 9, because jaw growth can be guided while the mixed dentition is still changing. If adult teeth are coming through crowded or in the wrong place, our guide to braces for kids explains what early treatment can and cannot do. Any orthodontic assessment should be with an AHPRA-registered dentist or specialist orthodontist.

The four types of teeth and what they do

• Incisors (8 adult, 8 baby): the flat, chisel-shaped front teeth that bite into food like scissors. Four upper, four lower.
• Canines (4 adult, 4 baby): the pointed “eye teeth” at the corners of the mouth, used to tear food. They have the longest roots of any tooth.
• Premolars (8 adult, none in baby teeth): between the canines and molars, with two cusps for crushing food. They replace the baby molars.
• Molars (12 adult including wisdom teeth, 8 baby): the large, flat-topped back teeth that grind food. The first adult molars at six are often called the “six-year molars”.

Each type wears differently. Incisors chip, canines guide the jaw sideways and wear at the tip, and molars are where most decay starts because their grooves trap food. Dentists number teeth by quadrant so that a note like “upper right 6” identifies the first molar on that side without ambiguity; it is the system you will see on quotes and health fund claims.

What if you have fewer than 32?

Most Australian adults do. Wisdom teeth are the usual reason, but teeth are also lost to decay, gum disease and injury, and some never form. Missing a wisdom tooth needs no treatment. Missing other teeth matters more, because neighbouring teeth tilt into gaps, opposing teeth over-erupt and chewing load shifts onto fewer teeth. Options for replacing a tooth range from an implant to a bridge or a partial denture; our guides to dental implant costs and dental bridge costs set out typical 2026 Australian prices.

Gum disease, not age, is the main reason adults lose teeth in Australia, and it is largely preventable. If you want to keep all 28 (or 32) for life, the recipe is unglamorous: brush twice a day with fluoride toothpaste, clean between your teeth daily, and see a registered dentist for a check-up every six to twelve months. For more on the structure of a tooth and why enamel never grows back, see our teeth facts page.

Common questions