What Are Supernumerary Teeth?

Adults normally have 32 permanent teeth, while children have 20 baby teeth. Though rare, extra teeth can develop in the mouth—a condition known as hyperdontia; the extra teeth themselves are called supernumerary teeth.

These teeth, which occur in .15 percent to 4 percent of the population, can appear in anyone but are more often associated with people who have Gardner's syndrome (a rare genetic disorder), Down syndrome, or in those born with a cleft lip. Supernumerary teeth appear twice as often in adult males as they do in adult females.

Types

Supernumerary teeth can appear anywhere in the mouth and are most often found among the permanent teeth. They can occur among baby teeth, but they tend to be harder to identify, as they often erupt normally, are shaped like other teeth, and are in correct alignment. A clinical examination by a dentist or an X-ray usually leads to the diagnosis.​

Supernumerary teeth usually appear as a single tooth, but sometimes multiple teeth are present, appearing separately or in clusters. In rare cases, as many as 30 supernumerary teeth can be present. 

There are several different types of supernumerary teeth. They include:

• Conical: These are the most common type and occur among permanent teeth. They have a normal root and appear near the central incisors, potentially displacing them.
• Tuberculate: These are barrel-shaped and impacted in the gums. They have abnormal roots and seldom erupt. They are located on the palate near the central incisors and can delay the eruption of those teeth.
• Supplemental: These are the most common type found among the baby teeth, usually appearing near the lateral incisors. They usually erupt.
• Molariform: These have a complete root and resemble the shape of premolars. They tend to appear next to the molars.

Causes and Risk Factors

The causes of supernumerary teeth are uncertain, though factors that may contribute to their appearance include genetics, overactivity of the dental lamina (cells that initiate tooth development), disease processes, and atavism (the reappearance of a trait no longer common because of evolution). Environmental factors that may cause hyperdontia are not yet known.

Conditions associated with supernumerary teeth include:

• Cleft lip and palate: A little over 22 percent of patients with cleft lip and/or palate develop supernumerary teeth.
• Cleidocranial dysplasia: This condition affects the development of the bones and teeth. The risk for developing supernumerary teeth in patients with cleidocranial dysplasia is 22 percent in the maxillary incisor area and 5 percent in the molar area.
• Down syndrome: This is the genetic disorder also known as trisomy 21.
• Ehler-Danlos syndrome: This is a set of inherited connective tissue disorders.
• Gardner syndrome: This genetic syndrome is characterized by the formation of colorectal polyps and increases the risk of colorectal cancer.

Complications

Supernumerary teeth can cause a variety of dental problems that interfere with normal oral function and health and present cosmetic issues. Some of the dental problems hyperdontia can cause include:

• Tooth impaction, where the supernumerary teeth interfere with the normal eruption of permanent teeth
• Crowding, displacement, and misalignment of normal permanent teeth
• Issues with proper chewing
• Fusion with permanent teeth
• Premature closure of spaces in between the teeth
• The formation of oral cysts or tumors
• The eruption of teeth into the nasal cavity
• Problems with bone grafting necessary for dental implants

Treatments

It is important to identify and treat supernumerary teeth as soon as possible. Your dentist or oral surgeon will be able to identify supernumerary teeth and suggest treatment for them. This may include having them extracted, which is normally done under local or general anesthesia. In some cases, supernumerary teeth may need to be cut and then removed in pieces.

You and your dentist should discuss the risks and benefits of extracting supernumerary teeth, as the procedure may increase the possibility of severing a nerve or blood vessel in the mouth. 

In children, it is recommended that supernumerary teeth be addressed early when the child gets his or her permanent teeth to avoid potential future issues they may cause. An orthodontist is often consulted in these cases. Oftentimes supernumerary teeth will need to be extracted before orthodontic treatment.

Supernumerary teeth fused with permanent teeth require endodontic treatment—also known as a root canal—to treat the tooth pulp as well as surrounding tissue.