Permanent Dentition: The Third Dentition

The permanent dentition, also known as the secondary dentition or adult teeth, represents the final set of teeth in humans. It typically erupts between the ages of six and twenty-one, replacing the deciduous (baby) teeth. This set is characterized by a specific arrangement and type of teeth, each with a distinct role in mastication (chewing).

Tooth Types in the Permanent Dentition

• Incisors: Eight incisors are located at the front of the mouth. Their sharp edges are designed for cutting food.
• Canines: Four canines, also known as cuspids or eyeteeth, are positioned next to the incisors. They possess a pointed cusp for tearing food.
• Premolars (bicuspids): Eight premolars are located behind the canines. They have two cusps and function to crush and grind food.
• Molars: Twelve molars are situated at the back of the mouth. Their broad, flat surfaces with multiple cusps are ideally suited for grinding and pulverizing food. They are further categorized into first, second, and third molars (wisdom teeth).

Molar Morphology and Function

Molars are the largest teeth in the permanent dentition. Their complex structure includes multiple cusps and roots, providing strong anchorage and efficient chewing action. The arrangement of cusps varies slightly between upper and lower molars and between the first, second, and third molars, reflecting functional adaptations to food processing. The third molars, often referred to as wisdom teeth, are the last to erupt and may be impacted (unable to erupt fully), requiring surgical removal.

Variations in Tooth Number

While the typical number of permanent teeth is 32, variations can occur. Supernumerary teeth (extra teeth) or agenesis (absence of teeth) can affect the total number. The absence of one or more wisdom teeth is a relatively common variation. The number of molars may be affected by these variations, but the typical adult complement is twelve.