Hyperdontia is a condition where a person has extra teeth beyond the usual number. Individuals with hyperdontia develop additional teeth, also known as supernumerary teeth. These extra teeth can appear anywhere in the dental arch and may be visible or remain hidden beneath the gum line. The presence of supernumerary teeth can vary, from a single extra tooth to multiple ones, and they can affect both primary and permanent dentition.
What Defines Hyperdontia
Supernumerary teeth are additional teeth that develop in the mouth beyond the standard count. They can be classified based on their shape (morphological classification) or by their location within the dental arch (topographical classification).
Morphological classifications
Morphological classifications describe the appearance of these extra teeth. Conical supernumeraries are peg-shaped and are the most common type, often found between the upper front teeth. Tuberculate supernumeraries are barrel-shaped, typically larger, and can have multiple cusps, often appearing in pairs and rarely erupting fully. Supplemental teeth resemble a normal tooth in shape and size, essentially a duplication of a tooth in the regular series. An odontoma refers to a disorganized mass of dental tissue that can appear as small tooth-like structures (compound odontoma) or a chaotic mass of tissue (complex odontoma).
Topographical classifications
Topographical classifications specify where these extra teeth are located. A mesiodens is the most common type, positioned between the two upper central incisors. Distomolars are found behind the molars, essentially acting as “fourth molars.” Paramolars grow beside the molars, either towards the tongue or the cheek.
Understanding the Causes
The exact cause of hyperdontia is not completely understood, though a combination of genetic and environmental factors is believed to contribute to its development. Genetic predisposition plays a role, as hyperdontia often runs in families, suggesting a hereditary link. Specific gene mutations, such as those in MSX1, MSX2, AXIN2, and PAX9, have been linked to the formation of extra teeth by disrupting tooth development.
Developmental abnormalities during early tooth formation, particularly an overactivity of the dental lamina—the tissue responsible for creating tooth buds—can lead to the presence of supernumerary teeth. Environmental factors, while less commonly identified, may also contribute, with some theories suggesting that trauma to the mouth or jaw during childhood could be a factor.
Hyperdontia is also associated with several genetic syndromes and conditions. These include Gardner’s Syndrome, which causes benign tumors and dental abnormalities, and Cleidocranial Dysplasia, a disorder affecting bone and tooth development. Other associated conditions are Down Syndrome, Ehlers-Danlos Syndrome, and Cleft Lip and Palate. In many instances, however, hyperdontia occurs without any known underlying syndrome or clear cause.
Effects on Oral Health
The presence of supernumerary teeth can lead to various issues affecting oral health and the normal development of the dentition. One common problem is crowding, where the extra teeth take up space, causing misalignment or improper spacing of existing teeth. This crowding can make it difficult to clean teeth properly, increasing the risk of tooth decay and gum disease.
Supernumerary teeth frequently cause the impaction of permanent teeth, meaning normal teeth become partially or fully trapped within the jawbone and cannot erupt properly. They can also lead to the displacement of adjacent teeth, causing them to shift from their proper positions or rotate. Delayed eruption of permanent teeth is another common consequence, particularly in children, as the extra teeth can block the pathway for normal teeth to emerge.
In some cases, supernumerary teeth can contribute to root resorption of adjacent teeth, where the roots of healthy teeth begin to break down. There is also a risk of cyst formation around impacted supernumerary teeth, which are non-cancerous sacs of fluid that can cause swelling or pain. These extra teeth can also interfere with orthodontic treatment, complicating efforts to align teeth and correct bite problems.
Diagnosis and Management
Diagnosing hyperdontia typically involves a combination of clinical examination and dental imaging. A dentist can often identify erupted supernumerary teeth during a routine visual inspection of the mouth. If extra teeth are not visible, dental X-rays, such as panoramic or periapical radiographs, are frequently used to detect hidden or impacted supernumerary teeth. For a more detailed view of the teeth, jawbone, and surrounding structures, a cone-beam computed tomography (CBCT) scan may be utilized.
Management strategies for hyperdontia vary depending on the specific situation, including the type, position, and potential impact of the supernumerary tooth on adjacent teeth. In some cases, if the extra teeth are not causing any problems or complications, a watchful waiting approach may be adopted, where the dentist monitors the situation over time. This is often considered when the supernumerary tooth is not interfering with other teeth or oral health.
However, if the supernumerary teeth are causing issues such as crowding, impaction, delayed eruption, or cyst formation, extraction of the extra tooth or teeth is commonly recommended. The decision to extract also considers factors like the tooth’s position, its morphology, and its potential to damage neighboring teeth. Orthodontic treatment may follow extraction to correct any misalignment or spacing issues caused by the hyperdontia.