Types of Teeth and Their Functions

The four front teeth in each arch are called incisors, and their function is to cut food with their sharp thin edges.  On each side of the incisors, at the corners of the mouth, are the canines.  These teeth have one cusp, or pointed edge, and are used for holding or grasping food, and are very strong, stable teeth.  Behind the canines are the premolars, which are designed for holding food like the canines because they have cusps, but they also function to crush food.  Sometimes these teeth are referred to as bicuspids, meaning two cusps, but this is not always accurate because some premolars may have three cusps.  Therefore the term premolar is preferred.  The teeth farthest back in the mouth are the molars.  These teeth have broad chewing surfaces with four or five cusps, and are designed for grinding food.  The incisors and canines are called anterior teeth, because they are located in the front of the mouth, while the premolars and molars are called posterior teeth because they are located in the back of the mouth.

Primary Dentition

Primary dentition diagram of primary teeth in order in the arch.

Permanent Dentition

Permanent dentition diagram of permanent teeth in order in the arch.

In addition to aiding in acquiring and chewing food, teeth perform several other important functions within the oral cavity.  They begin the digestive process by breaking down food; they protect the oral cavity; they aid in proper speech; and they affect physical appearance.  There are several types of teeth, and each performs its own special function in the chewing process, depending on its size, shape and location within the jaws.  Starting at the midline, the permanent dentition is comprised of incisors, canines, premolars and molars.  The primary dentition is the same except it has no premolars.
Incisors
There are four incisors in each arch.  Two central incisors and two lateral incisors.

• Location – the central incisors are side by side at the midline.  There is a lateral incisor on each side of the central incisors.
• Shape – single rooted, crowns are arched and angle toward one sharp incisal edge.
• Function – to cut or incise food with their thin edges.

Canines
There are two canines in each arch.  They are sometimes referred to as cuspids.

• Location – next to the lateral incisors, establishes the cornering of the arches.
• Shape – anchored with the longest root, one pointed cusp.
• Function – used for holding, grasping, and tearing food. Referred to as the cornerstone of the mouth.

Premolars
There are for premolars in each arch.  Two first premolars and two second premolars.  They are sometimes referred to as bicuspids.  There are no premolars in the primary dentition.

• Location – first premolars are next to the canines followed by the second premolars.
• Shape – maxillary first premolars have a bifurcated root, all others have one root, one prominent cusp with one or two lesser lingual cusps.
• Function – holding food, like canines because they have cusps; also to crush food.

Molars
There are three molars in each arch of the permanent dentition.  Two first molars, two second molars and two third molars.  Third molars are sometimes called wisdom teeth.  There are two molars in each arch of the primary dentition.  Two first molars and two second molars.

• Location – first molars are next to the second premolars, second molars next to the first molars and third molars next to the second molars.  The third molars are the farthest teeth in the mouth.
• Shape – bifurcated or trifurcated roots, broad chewing surfaces with four to five cusps.
• Function – grinding food.

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