Weird Dental Condition of the Day: Hyperdontia


Most humans grow 20 baby teeth during the early years of their life, which are then replaced by 32 adult teeth during their adolescent and teen years. However, some people — estimates range from less than 1% to 4% of the population — develop more than the normal number of baby or adult teeth, a condition called hyperdontia. When you hear that someone has extra teeth (called “supernumerary teeth”), imaginations often run wild with thoughts of freakish horror movie monsters with hundreds of pointy teeth, but in reality, just one extra tooth (i.e., 21 baby teeth or 33 adult teeth) would qualify as hyperdontia.

And most cases of hyperdontia are just that: a single extra tooth. Cases of multiple supernumerary teeth do occur, but are often related to other conditions, such as cleft lip/palate. In many cases of hyperdontia, the extra teeth never even fully emerge from the gums; however, they might block or crowd nearby teeth, causing other dental problems.

Supernumerary teeth can appear anywhere along the normal ring of teeth, but the most common location is the upper front teeth (“maxillary incisors”); the extra teeth most often are malformed, 70 to 80% of them resembling pegs.

Hyperdontia is more common with adult teeth than baby teeth; a 1999 report found adult teeth (even in minors) had more than twice as high an incidence of supernumerary teeth. It’s believed this is due to the fact that parents don’t often notice supernumerary baby teeth because they more frequently appear fully formed and aligned with the other teeth in the child’s mouth. Boys’ and girls’ baby teeth experience hyperdontia at about an equal rate, but when it comes to adult teeth, the condition strikes males twice as often as females.

The cause of hyperdontia isn’t known, but it’s believed to be somewhat hereditary, since it’s more common in the relatives of affected children than in the general population. Other theories of potential causes revolve around unusual occurrences — either division or hyperactivity — of dental tissue early in the formation of the tooth.

Because of the potential of hyperdontia causing other dental problems — including cysts or tumors — treatment typically involves removal of the supernumerary teeth when possible. However, they may be left in the mouth under certain circumstances, such as when the related teeth have already successfully come in and the removal would jeopardize them.

(Sources: National Center for Biotechnology Information,, Wikipedia)