"Wisdom teeth" are a type of molar. Molars are chewing teeth located at the very back of the mouth. Human molars are divided into first, second, and third molars.
Third molars — also known as "wisdom teeth" — usually erupt behind the second molars (if there is space and they are correctly aligned) during late adolescence or early adulthood. There can be up to four wisdom teeth: upper left, upper right, lower left, and lower right.
What are "impacted wisdom teeth"?
In dental terminology, an "impacted" tooth is one that has failed to fully erupt and take its place in the dental arch. This may occur due to a lack of space in the jaw or because of the tooth’s improper angle.
Classification of impacted wisdom teeth
Dentists use specific terms to describe the position of impacted wisdom teeth. The most common type is mesial impaction. The term "mesial" indicates that the tooth is tilted forward, toward the front of the mouth.
Other types of impaction (listed here in descending order of frequency) include vertical impaction, horizontal impaction, and distal impaction.
Impacted wisdom teeth are classified not only by the direction of impaction — mesial, vertical, horizontal, or distal — but also by the depth: soft tissue impaction and bony impaction. "Bony impaction" means the wisdom tooth remains within the jawbone, while "soft tissue impaction" means it has passed through the bone but hasn't fully emerged from the gums.
Why do wisdom teeth grow incorrectly?
Many modern theories suggest that improper eruption of wisdom teeth occurs because the human jaw is too small to accommodate them. This is explained by the fact that the jaws of modern humans are smaller than those of prehistoric ancestors — due to our consumption of softer food that doesn't require strong, large teeth for chewing.
Proponents of these theories believe that as humanity continues to evolve, the time may come when people no longer develop wisdom teeth at all. Even today, it is not uncommon to find individuals with only 1–2 wisdom teeth or none at all.