Having 28 teeth as an adult is common and often considered the standard for a fully functional mouth. The difference between this count and the maximum possible number of teeth relates almost entirely to the presence or absence of the final molars. This number represents a healthy dentition fully capable of all normal oral functions, including biting, tearing, and grinding food.
Understanding the Full Set of Adult Teeth
The maximum number of teeth an adult can possess is 32, a full set of permanent dentition symmetrically distributed with 16 teeth in the upper and lower jaws. These teeth are categorized into four groups, each specialized for a different function in food preparation.
The eight incisors are the flat, sharp front teeth used for cutting and biting food. Flanking these are the four pointed canines, designed for tearing and gripping tougher materials. The eight premolars, or bicuspids, help to crush and grind food. Finally, the 12 molars, which include the four third molars, have broad, flat surfaces for grinding.
The Role of Wisdom Teeth in the 28-Count
The four teeth accounting for the difference between a full set and 28 teeth are almost always the third molars, commonly called wisdom teeth. These teeth are the last to develop and typically erupt between the ages of 17 and 25. Their absence is the primary reason why 28 teeth are frequent in the adult population.
Wisdom teeth are routinely removed because the human jaw often lacks enough room to accommodate them properly. When space is limited, they may become impacted, meaning they are partially or fully trapped beneath the gum line. Impaction can cause pain, swelling, and potential damage to adjacent teeth. Even if they erupt fully, their position at the back of the mouth makes them difficult to clean, leading to a high risk of decay or gum disease.
It is also common for people to be naturally missing one or more of these teeth due to a developmental anomaly known as congenital absence. This condition means the teeth never developed. Whether removed or congenitally absent, the lack of these four third molars results in the 28-tooth count for a healthy adult.
When Missing Teeth Indicate Other Issues
While having 28 teeth is normal, missing any of the other permanent teeth may suggest an underlying dental or developmental issue. Tooth loss not involving the third molars often occurs due to severe dental decay or periodontal disease, which are the main reasons adults lose teeth later in life. Trauma to the mouth can also result in premature tooth loss.
A person may also be born without teeth other than the third molars, a condition known as hypodontia. This developmental condition involves the congenital absence of one to six permanent teeth, most commonly affecting the second premolars and the upper lateral incisors. Hypodontia can be hereditary or related to environmental factors that disrupt tooth development.