What is hyperdontia?

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Hyperdontia is a condition where a person has more than the normal number of teeth in their mouth.

Hyperdontia, called supernumerary teeth, is a condition where a person has more than the normal number of teeth in their mouth. For adults this number is 32, for children it is 20. The extra number of teeth could be anywhere from one to 12 or more.¹

Having extra teeth is not common. Hyperdontia affects only between 0.15% and 1.9% of the population. In almost all studies, males are more frequently diagnosed with supernumerary teeth than females.²

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The most common location for these abnormalities to occur is in the upper incisor area, the front four teeth in the mouth on the top and bottom. These teeth may grow in any direction, causing complications as the teeth grow in. The extra teeth can resemble full-sized teeth, but they are usually cone-shaped.

What causes hyperdontia?

Although causes for hyperdontia are not completely understood, patients with hyperdontia tend to have parents or grandparents who also have supernumerary teeth. It is passed down genetically more often than it occurs on its own.  

Dichotomy of tooth bud

Prior to a tooth forming and erupting it is called a tooth bud. A splitting of this bud is called a dichotomy of the tooth bud. When this dichotomy happens two teeth form rather than one, causing hyperdontia.

Hyperactivity theory

The Hyperactivity Theory is the most widely accept theory for hyperdontia when not also linked with another condition. The dental lamina is where new teeth form and are grown. In those who have more than the normal set of teeth, this area may be hyperactive. Hyperactivity of the dental lamina causes more teeth to grow in than would normally be expected.³

Links to other conditions

It is rare that hyperdontia occurs on its own, usually the condition is paired with another genetic condition including:  

  • Cleft lip or palate

  • Cleidocranial dysostosis

  • Gardner's syndrome

  • Fabry disease

  • Ellis-van Creveld syndrome

  • Trico–Rhino–Phalangeal syndrome

  • Rubinstein-Taybi syndrome

  • Nance-Horan syndrome

Many times, the presence of hyperdontia is an earlier indicator of the above conditions and can be used to help diagnose the condition itself.

Diagnosis of hyperdontia

An early diagnosis is important, as treatment and detection can occur as early as two years of age. Clinicians can note any abnormalities with tooth eruption and link these abnormalities with the possible presence of extra teeth.

For adults, it is relatively simple for dentists to diagnose hyperdontia in their patients. Many times, the extra tooth has already erupted and is visible in the mouth with the naked eye. If this is not the case, the extra teeth will show up in a panoramic X-ray. Oftentimes these teeth will remain impacted, which is why the clinician needs to take an X-ray to be sure.

Hyperdontia risks

There are many risks associated with hyperdontia. Although some are painful, none are life-threatening. Patients can live relatively happily with minimal pain cause by hyperdontia.

Crowding of teeth

Teeth are designed to fit in the mouth in a certain way, when a new tooth is added it causes the teeth to move closer, overlap, and become overcrowded. Crowded teeth can be uncomfortable and are harder to brush and floss well.

Root abnormalities

With less room for each tooth to fully develop the root of each tooth can struggle to develop properly. Rather than developing fully and straight, supernumerary teeth can cause roots to bend, twist, and be short than normal. These abnormalities also can affect the mandible, or jaw, causing pain and discomfort.

Rotation or tooth movement

As more teeth are added and as the mouth begins to get more crowded, it causes teeth to move throughout the mouth. Teeth also may simply rotate, turning sideways to accommodate the new teeth.

Formation of cysts

In 11% of cases, cysts are formed as a result of hyperdontia. These cysts can become painful and inflamed and may need to be removed as a result.

Impacted teeth

If the supernumerary tooth cannot find a way to erupt into the mouth it may remain impacted, or unerupted, under the gumline. This is similar to having impacted wisdom teeth, these teeth will need to be removed to prevent complications later on.

Eruption into the nasal cavity

Rarely, the extra tooth may invert and erupt into the nasal cavity. These teeth may appear on X-rays as a white mass in the nasal cavity.

Hyperdontia treatment

Leave the extra tooth in

In some cases, it is possible to simply leave the extra tooth in if it is not causing pain or discomfort and is not in danger of causing future health issues. Due to the overcrowding and movement of teeth, people with hyperdontia can have crooked teeth. Many times, patients with hyperdontia get teeth removed for aesthetic purposes.

Remove the extra tooth

For patients with hyperdontia the treatment is simple if the tooth has erupted into the mouth. The clinician simply will remove the tooth just like any other tooth extraction.

In cases of impaction, the clinician will remove the tooth much as they would any other impacted tooth, through surgery. This is an outpatient procedure in which the surgeon will cut into the gum line and remove the tooth.

If the tooth has erupted into the nasal cavity it will require a more specialize surgical procedure to be removed as it is no longer residing only in the mouth.

Continued monitoring

After tooth extraction, it is important for the clinician to continue to monitor their patient throughout their life as the supernumerary tooth can come back. If it is noticed that the tooth has returned, steps can be taken to have it extracted again or simply to be more proactive in the treatment of the tooth.

Moving forward

With some diligence and routine visits to a dentist, hyperdontia can be caught and treated in its early stages before becoming painful or requiring expensive orthodontics to straighten teeth.

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Brought to you by The Guardian Life Insurance Company of America (Guardian), New York, NY. Material discussed is meant for general illustration and/or informational purposes only and it is not to be construed as tax, legal, investment or medical advice. It is not dental care advice and should not be substituted for regular consultation with your dentist. If you have any concerns about your dental health, please contact your dentist's office.


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  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4319293/ (Last accessed February 2020)

  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3184724/ (Last accessed February 2020)

  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4576660/ (Last accessed February 2020)