Supernumerary teeth are extra teeth that form in the jaw beyond the normal number of teeth. This condition is also known as hyperdontia and can affect any area of the dental arch. While not a widespread occurrence, supernumerary teeth are estimated to be present in 0.1% to 3.8% of the permanent dentition in the general population. Understanding the morphology and position of these additional teeth is the first step in managing the potential complications they can cause.
Defining Supernumerary Teeth and Their Types
Supernumerary teeth are classified based on their location and morphology. Positional classifications include the mesiodens, the most common type, located between the two upper central incisors. A paramolar is situated beside a molar, while a distomolar forms behind the last molar in the dental arch.
In terms of morphology, there are four main types, including supplemental and rudimentary forms. Supplemental teeth closely resemble a normal adjacent tooth in both size and shape. Rudimentary teeth have an abnormal morphology and are divided into conical, tuberculate, and odontoma types.
Conical teeth are small and peg-shaped, whereas tuberculate types are often barrel-shaped with more than one cusp. An odontoma is a disorganized mass of dental tissue, sometimes classified as a benign tumor. These extra teeth may be erupted and visible in the mouth or remain impacted, meaning they are hidden within the jawbone or soft tissue.
Potential Causes of Extra Teeth
The cause for the development of supernumerary teeth is not fully understood, but theories center on developmental and genetic factors. The most widely accepted explanation is the hyperactivity of the dental lamina, the tissue in the developing jaw that gives rise to the tooth buds.
It is believed that an over-proliferation or continued survival of these epithelial cells leads to the formation of an extra tooth bud. Another theory suggests that the regular tooth bud splits, a process known as dichotomy, resulting in two teeth where only one was intended.
Genetic factors also play a part, as supernumerary teeth are more common in the relatives of affected patients. This condition can be inherited through an autosomal dominant or recessive pattern. The presence of multiple extra teeth is sometimes associated with specific genetic syndromes, such as Gardner syndrome, Cleidocranial Dysplasia, and Cleft Lip and Palate.
Complications Caused by Supernumerary Teeth
The presence of an additional tooth can lead to dental problems, particularly when the tooth remains impacted in the jaw. One common issue is the prevention or delay of eruption for the adjacent permanent teeth. This retention is often seen with upper central incisors, where a mesiodens physically blocks the path of the developing tooth.
The extra tooth can also cause the displacement or rotation of neighboring teeth, resulting in malocclusion or a “bad bite.” Crowding in the dental arch and the formation of a gap between teeth are frequent consequences, leading to aesthetic concerns. Furthermore, a supernumerary tooth can press against the root of an adjacent permanent tooth, causing external root resorption, where the body dissolves the tooth root.
More serious complications involve the development of fluid-filled sacs around the crown of an unerupted tooth. These are known as follicular cysts or dentigerous cysts, and they can expand, leading to destruction of the surrounding bone tissue. The extra tooth may also migrate into ectopic locations, such as the nasal cavity or the maxillary sinus.
Diagnosis and Treatment Options
Early detection of supernumerary teeth is important to minimize the risk of complications for the developing permanent dentition. Clinical examination can sometimes reveal an extra tooth, but dental X-rays, or radiographs, are the primary diagnostic tool. A panoramic radiograph provides a broad, two-dimensional view of the entire jaw, often giving the first indication of an extra tooth.
More advanced imaging, such as Cone-Beam Computed Tomography (CBCT), is valuable for precise surgical planning. CBCT offers a three-dimensional view, accurately showing the exact location of the supernumerary tooth and its proximity to the roots of adjacent teeth and anatomical structures. This detail is necessary to determine the appropriate method of removal.
The treatment decision involves a choice between observation, often called “watchful waiting,” and surgical extraction. Observation is typically chosen for asymptomatic, erupted teeth that are not causing problems, or for cases where the risk of surgery outweighs the potential benefits. Extraction is generally recommended for all impacted supernumerary teeth, particularly those causing or threatening complications like impaction, displacement, or cyst formation. The timing of extraction is often debated, but removing the extra tooth early, before the adjacent permanent tooth’s root is fully formed, may allow for spontaneous, normal eruption.