Teeth Types, Function and Numbering

There are 32 teeth in the full adult set, referred to as permanent teeth. Children have just 20 teeth, and these are called deciduous teeth, also known as ‘milk’ teeth or ‘baby’ teeth.

In a full set of permanent teeth, there are 16 teeth in the lower jaw, and 16 teeth in the upper jaw, although it is not unusual to find teeth that are missing or that have “drifted” into a space for another tooth, or simply have not come through (technically referred to as non-eruption).

Types of Teeth
Using the illustration below, the teeth are again split up from the 4 quadrants into 4 separate types, each tooth having a unique function.

Incisor teeth are shovel shaped at the front of your mouth are used for cutting or slicing food. These teeth are at the front of your mouth and are called anterior teeth.

Canine teeth (dog teeth) are used for stabbing or piercing food and have an extremely long root compared to all the other teeth. These teeth are at the front of your mouth and are also called anterior teeth.

Premolar teeth are used for chewing your food. These are your first row of back teeth or posterior teeth.

Molars are used for mastication to ensure your food passes properly down your throat and into your stomach. Molars have a large flat chewing surface that can break down food easily. Molars are right at the back of your mouth and are again called posterior teeth.

Common Tooth Notation
One question that we commonly get asked is how we number teeth. The upper and lower dental arches are split into 4 quadrants, and denoted as follows:

Upper Right Quadrant
Upper Left Quadrant
Lower Right Quadrant
Lower Left Quadrant

Each tooth has an individual number to identify it in each quadrant.
Eg, if we use your upper left hand quadrant as an example, then the teeth are most commonly notated as follows:

You will see that the teeth are numbered in each individual quadrant at the patient would view them, ie the UL8 or I_8 is the third molar or wisdom tooth on your upper jaw, on your own left hand side. All teeth are therefore located by reference to the patient, and not how the dentist looks at the patient.

There is no correct or incorrect method of notation, and each dentist is free to use any accepted practice that they wish.

FDI Tooth Notation
Some dentists use the FDI (International Dental Federation) technique of tooth notation. This is a different method of numbering, which is commonly used in the USA. Again with FDI notation, the teeth are split into four quadrants, and a separate number is given to each tooth in each quadrant, as follows:

18 17 16 15 14 13 12 11    21 22 23 24 25 26 27 28
48 47 46 45 44 43 42 41    31 32 33 34 35 36 37 38