The human mouth accommodates two distinct sets of teeth over a lifetime. The total number of teeth changes significantly from infancy through adolescence, progressing from a temporary set to a larger, more robust permanent set adapted for chewing, speech, and maintaining jaw structure.
The Primary Set: Teeth in Childhood
The initial set of teeth, commonly known as baby teeth, are medically termed the primary or deciduous dentition. A complete primary set consists of 20 teeth, distributed with 10 in the upper jaw and 10 in the lower jaw. Eruption typically begins around six months of age, with the full set generally in place by the child’s third birthday.
Primary teeth serve as placeholders in the jaw, maintaining the correct spacing and alignment for the larger, permanent teeth developing beneath the gums. They are naturally shed, starting around age six. This temporary set lacks premolars and third molars, which are unique additions to the adult dentition.
The Permanent Set: Teeth in Adulthood
The transition to permanent teeth begins in middle childhood, typically around age six, with the eruption of the first molars. The full adult dentition includes 32 permanent teeth. This count is made up of eight incisors, four canines, eight premolars, and twelve molars.
Many adults possess only 28 teeth, which is still considered a complete and functional set. The difference of four teeth is accounted for by the third molars, commonly known as wisdom teeth. These are the last teeth to emerge, typically appearing between the ages of 17 and 25. Due to evolutionary changes, there is often insufficient space for these third molars, leading to their surgical removal in many individuals.
Understanding Tooth Types and Function
The 32 permanent teeth are categorized into four types, each with a specialized shape and purpose that contributes to the initial stages of digestion. The eight incisors, positioned at the front of the mouth, have sharp, flat edges designed for biting and cutting food.
Adjacent to the incisors are the four canines, characterized by a pointed, cusp-like shape. These teeth are structured for grasping and tearing tougher foods, such as certain meats.
Behind the canines are the eight premolars, also known as bicuspids. They feature two pointed cusps on their chewing surface and begin the process of crushing food into smaller pieces.
The twelve molars, located at the back of the mouth, are the largest teeth. They have a broad, flat surface with multiple cusps, making them the primary teeth for grinding and pulverizing food before it is swallowed.