The wisdom teeth, officially known as third molars, are the last set of permanent teeth to emerge in the mouth. These molars typically make their appearance in the late teens or early twenties, marking the completion of the adult dentition. Historically, these teeth were helpful for grinding the coarse diet of earlier human ancestors. Today, modern diets and smaller jaw structures mean they often have little functional role. A person normally develops four wisdom teeth, with one tooth positioned at the back of each of the four quadrants of the mouth.
The Standard Count and Supernumerary Teeth
Having eight true third molars, meaning two full sets of wisdom teeth, is anatomically not how the mouth is structured for tooth development. However, a person can possess a total of eight molars in the back of the mouth—four true third molars plus four extra molars—due to a condition known as hyperdontia. Hyperdontia is the presence of any teeth in addition to the standard complement of 32 permanent teeth. These extra teeth are called supernumerary teeth. The extra molars that contribute to this higher count are not considered true third molars, but they grow in the same general region. This anomaly is rooted in the dental lamina hyperactivity theory, which suggests an excessive or prolonged activity of the tissue responsible for tooth formation. Supernumerary teeth are relatively rare, occurring in an estimated one to four percent of the population.
Specific Nomenclature for Extra Molars
When extra molars appear in the back of the mouth, specific terms are used to describe their location relative to the third molars. These accessory molars are classified as either distomolars or paramolars. Distomolars are supernumerary teeth situated directly behind the true third molar, meaning they are the most distal tooth in the arch. They are sometimes referred to as fourth molars. Paramolars, by contrast, are extra teeth located to the side of the existing molars, typically on the buccal (cheek side) or lingual (tongue side). Both distomolars and paramolars may present with normal morphology or be rudimentary, meaning they are smaller and misshapen. The crucial distinction is that neither of these types are considered the genetically intended third molars.
Dental Implications of Having More Than Four
The presence of any supernumerary molar introduces a clinical concern due to its potential to disrupt the normal dental arch. One of the most common issues is severe crowding, which occurs when the excess tooth takes up space needed by the other 32 teeth. This crowding can cause adjacent permanent teeth to become displaced, rotated, or pushed out of proper alignment. Extra molars often fail to erupt fully, leading to impaction, where they remain trapped within the jawbone or gum tissue.
An impacted supernumerary tooth can obstruct or delay the eruption of the adjacent true wisdom tooth or the second molar. This obstruction increases the risk of developing a dentigerous cyst—a fluid-filled sac that forms around the crown of an unerupted tooth—which can damage surrounding bone and roots. Diagnosis of these anomalies requires a thorough dental examination, including dental X-rays, which reveal the presence and exact location of unerupted teeth. Because of the associated risks of crowding, impaction, and cyst formation, the recommended treatment is often the surgical removal of the supernumerary tooth. Timely extraction helps prevent long-term complications and promotes a healthier environment for the rest of the dentition.