The final four adult teeth should come through during late teens totalling 32 adult teeth. The descriptions below explain the functions of each of the teeth. To view a model showing all the milk and adult teeth erupting, take a look at the timeline showing the lifetime of teeth.
Permanent incisors: These are the front teeth, and there are 8 of them altogether (four at the top and four at the bottom). They are usually the first permanent teeth to come through, and are good for cutting into food (for example biting into an apple). You can tell which are the incisors by their flat edge at the top, and because they each have only one root.
Permanent canines: These front teeth are also known as 'eye teeth', and are more pointed in shape than the incisors, but like the incisors they each have a single root. There are 4 altogether, and in animals such as dogs and cats the canines are much longer, and are used for tearing off chunks of food. In humans they are smaller in size, and are good for cutting into food similar to incisors.
Premolars: These are the new, adult back teeth which replace the first and second deciduous molars. There are eight altogether, four first premolars and four second ones. Deciduous teeth don't have premolars as back teeth, just molars.
Permanent molars: These are the larger back teeth, which are good for crushing food into smaller pieces before being swallowed. This is known as chewing. Molars usually have more than one root each, and have irregular, or 'bumpy' surfaces with grooves called 'fissures'. There are first, second and third permanent molars, which come through in that order.
First permanent molars: The four first permanent molars are similar in size to the second molars and come through at around age 6 to 8 years.
Second permanent molars: The four second permanent molars are similar in size to the first permanent molars and come through at around age 12 years.
Third permanent molars: These are the very last of the adult teeth to appear between age 18 and 21 years, and are also called 'wisdom teeth'. There are four, and they come through at the very back and sometimes cause problems if there isn't enough room for them.