Hyperdontia involves having extra teeth. It is not typically painful, but it can cause complications that lead to pain and swelling.
People generally have 20 baby teeth, which grow during childhood, and 32 permanent teeth to replace them.
Sometimes, however, people grow extra teeth. This is called hyperdontia, and the dentist may refer to the extra teeth as “supernumerary” teeth.
One or more supernumerary may develop in one or more locations within the mouth. Extra teeth may be baby or permanent teeth.
In permanent teeth, the prevalence of hyperdontia ranges from 0.1% to 3.8%. In baby teeth, the prevalence is 0.3% to 0.6%.
When it occurs in permanent teeth, hyperdontia is twice as common among males, compared with females.
In this article, learn about the types and causes of hyperdontia. We also describe treatments and possible complications.
Dentists classify supernumerary teeth by their shape and location.
An extra tooth may be “supplemental” and have the same shape and anatomy as a nearby tooth. Or, it may be “rudimentary,” in which case it has an abnormal shape and is often smaller than surrounding teeth.
A dentist may also classify a rudimentary tooth as “tuberculate” if it has a tube- or barrel-like shape. A rudimentary tooth may instead be “conical,” with a broad base and narrow top.
In other cases, a dentist may find that an extra tooth is an odontoma, a benign tumor composed of dental tissue that has formed irregularly.
An odontoma may be compound, made up of small tooth-like structures, or complex, comprising a mass of tissue that does not resemble a tooth.
Extra teeth can form throughout the mouth. The dentist may also classify them by location, as follows:
- Mesiodens. This is an additional tooth growing between the two central incisors — the two flat teeth at the front of the upper jaw.
- Distomolar. This refers to an extra tooth growing in line behind the molars — the large, flat teeth at the back of the mouth.
- Paramolar. This is an additional tooth growing next to one of the molars, out of line with the other teeth.
Most extra teeth are mesiodens.
Hyperdontia may develop due to environmental or genetic factors. In some cases, the cause is unclear.
Having extra teeth can be associated with genetic disorders and syndromes, including:
- Gardner’s syndrome. This rare disorder also causes benign growths to form in various areas, and it increases the risk of colon cancer.
- Cleidocranial dysplasia. This disorder also causes the abnormal formation of bones in the skull and collar area.
- Cleft lip and palate. These congenital irregularities occur when a baby’s lip or mouth does not form correctly in the uterus.
- Fabry disease. This involves a deficiency of the enzyme alpha-galactosidase A. It affects many areas, including the teeth, skin, brain, and nervous system.
- Ellis van Creveld syndrome. Another rare disorder, this causes short limb dwarfism and additional fingers and toes. It may also involve congenital heart abnormalities.
- Nance-Horan syndrome. In addition to causing dental abnormalities, this involves congenital cataracts that result in poor vision.
- Rubinstein-Taybi syndrome. This leads to distinctive facial features, short stature, and intellectual disability, as well as problems with the teeth, eyes, heart, and kidneys.
- Trichorhinophalangeal syndrome. This leads to bone and joint malformations, distinctive facial features, and abnormalities of the skin, hair, and teeth.
Other genetic syndromes can also cause supernumerary teeth. For doctors, the presence of extra teeth can be an important clue, facilitating early diagnosis.
Hyperdontia is the medical term for extra teeth. These teeth may develop:
- singly or in multiples
- on one or both sides of the mouth
- in the upper or lower jaws, or both
If an extra tooth is visible, the dentist may describe it as “erupted.” If it is hidden below the gumline, they may describe it as “impacted.”
The majority of extra teeth are single and impacted. Two extra teeth only occur in 12–23% of hyperdontia cases. In fewer than 1% of all cases, there are more than two extra teeth.
Also, as many as 98% of supernumerary teeth are in the upper jaw.
Hyperdontia does not typically cause pain. However, if the teeth are overcrowded or other complications develop, there can be pain and swelling around the extra tooth or teeth.
A dentist will diagnose hyperdontia by inspecting the mouth.
They will also take X-rays to check for any extra teeth that have not broken through the gumline.
Treatment depends on whether the supernumerary teeth are likely to cause complications.
Usually, extra teeth cause no symptoms. A person may have no idea that they are there, and a dentist may only detect them on an X-ray.
If supernumerary teeth are causing no symptoms or complications, they may not require treatment.
However, in most cases of hyperdontia, the extra teeth need to be removed, even if they are not causing discomfort.
A dentist may recommend removal if extra teeth cause:
- difficulties chewing or eating
- problems cleaning the teeth, which could lead to gum disease
- overcrowding or crooked teeth
- a delay in the eruption of permanent teeth
- damage to unerupted permanent teeth
- any discomfort
If additional teeth develop due to a genetic disorder, it may also be a good idea to remove them.
Certain genetic disorders are the leading risk factors for hyperdontia.
Even when no genetic syndrome is present, supernumerary teeth may run in families.
The majority of supernumerary teeth cause complications.
Some complications of hyperdontia include:
- diastema, a gap between teeth
- crooked teeth
- pain and inflammation
- infections, such as gingivitis
- delayed eruption of permanent teeth
- impaction of permanent incisors
- abnormal root formation in nearby teeth
- cystic lesions around the teeth
- baby teeth not coming out in time
If a person notices extra teeth, especially any that are not in line with surrounding teeth, they should see a dentist.
In general, consult a dentist about any swelling or pain in the mouth.
A parent or caregiver should consult a dentist if they notice that a child’s permanent teeth are late to grow in or if there are large gaps between permanent teeth — especially the front incisors.
It is important to attend routine dental examinations. A dentist may spot hyperdontia during a regular checkup or X-ray.
According to research, an early diagnosis leads to a better outlook for people with hyperdontia.
A dentist may be able to diagnose the issue in children as young as 2 years old.
Once the extra tooth is removed, any discomfort typically ceases. If the surrounding teeth are crooked or have been otherwise affected, additional dental and orthodontic work can resolve these issues.
Hyperdontia involves having extra teeth. The cause is not always clear, but it can characterize certain genetic conditions.
Although hyperdontia often causes complications, many are minor. A doctor usually recommends removing the extra tooth.
Anyone who has concerns about their oral health should contact a dentist.