Extra teeth, also called supernumerary teeth or hyperdontia, is a condition in which the jaws contain more teeth – usually permanent teeth – than the usual number. These extra teeth are usually categorized in two ways, by their shape and by their position.
They can be of normal shape but simply be extra (called “supplemental”). They can be barrel-shaped (“tuberculate”), peg-shaped or conical, multiple shapes (“compound odontoma”), or an undefined shape (“complex odontoma”).
They can form in several places. They may be “mesiodens” (midline), “paramolar” (on either side of the molars), or “distomolar” (behind the molars). Most often occuring is the mesiodens, which is peg-shaped and grows between the top two center teeth.
The causes are unknown and may be either genetic or environmental. They are, however, usually associated with other conditions such as Fabry disease, Ellis-van-Creveld syndrome, Nance-Horan syndrome, Rubinstein-Taybi syndrome, Gardner's syndrome, cleidocranial dysostosis, and trico-rhino-phalangeal syndrome. They are also related with cleft lip and palate.
Supernumerary teeth are usually treated with a combination of surgery and orthodontia.