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Hyperdontia

Hyperdontia

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Encyclopedia
Hyperdontia is the condition of having supernumerary teeth, or teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

 which appear in addition
Supernumerary body part
Supernumerary body parts are most commonly a congenital disorder involving the growth of an additional part of the body and a deviation from the body plan. Body parts may be easily visible or hidden away, such as internal organs....

 to the regular number of teeth.

Types


Supernumerary teeth can be classified by shape and by position. The shapes include:
  • Supplemental (where the tooth has a normal shape for the teeth in that series);
  • Tuberculate (also called "barrel shaped");
  • Conical (also called "peg shaped");
  • Compound odontome (multiple small tooth-like forms);
  • Complex odontome (a disorganized mass of dental tissue)


When classified by position, a supernumerary tooth may be referred to as a mesiodens, a paramolar, or a distomolar.

The most common supernumerary tooth is a mesiodens, which is a mal-formed, peg-like tooth that occurs between the maxillary central incisor
Maxillary central incisor
The maxillary central incisor is a human tooth in the front upper jaw, or maxilla, and is usually the most visible of all teeth in the mouth. It is located mesial to the maxillary lateral incisor. As with all incisors, their function is for shearing or cutting food during mastication . There are...

s.

Fourth and fifth molars that form behind the third molars are another kind of supernumerary teeth.

Causes


There is evidence of hereditary factors along with some evidence of environmental factors leading to this condition. Many supernumerary teeth never erupt, but they may delay eruption of nearby teeth or cause other dental problems. Molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....

-type extra teeth are the rarest form. Dental X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

s are often used to diagnose Hyperdontia.

It is suggested that supernumerary teeth develop from a second tooth bud arising from the dental lamina
Dental lamina
The dental lamina is a band of epithelial tissue seen in histologic sections of a developing tooth. The dental lamina is first evidence of tooth development and begins at the sixth week in utero or three weeks after the rupture of the buccopharyngeal membrane. It is formed when cells of the oral...

 near the regular tooth bud or possibly from splitting the regular tooth bud itself. Supernumerary teeth in deciduous (baby) teeth
Deciduous teeth
Deciduous teeth, otherwise known as reborner teeth, baby teeth, temporary teeth and primary teeth, are the first set of teeth in the growth development of humans and many other mammals. In some Asian countries they are referred to as fall teeth as they will eventually fall out, while in almost all...

 are less common than in permanent teeth.

Related conditions


A similar condition is hypodontia
Hypodontia
In dentistry, hypodontia is the condition at which the patient has missing teeth as a result of their failure to develop. Hypodontia describes a situation where the patient is missing up to 6 teeth, excluding the 3rd molars. Missing third molars occur in 9-30% of population...

, in which there are fewer than the usual number of teeth.

Hyperdontia is seen in a number of disorders, including Gardner's syndrome
Gardner's syndrome
Gardner syndrome, also known as familial colorectal polyposis, is an autosomal dominant form of polyposis characterized by the presence of multiple polyps in the colon together with tumors outside the colon...

 and cleidocranial dysostosis
Cleidocranial dysostosis
Cleidocranial dysostosis, also called Cleidocranial dysplasia, is a hereditary congenital disorder due to haploinsufficiency caused by mutations in the CBFA1 gene also called Runx2, located on the short arm of chromosome 6....

where multiple supernumerary teeth are seen that are usually impacted.

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