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 6 teeth or less, excluding the 3rd molars or wisdom teeth. Missing third molars occur in 9-30% of population. In primary dentition the maxilla is more affected, with the condition usually involving the maxillary lateral incisor.

The condition of missing over 6 teeth, excluding 3rd molars or wisdom teeth, is called oligodontia. The condition for missing all teeth, either primary and/or permanent), is called anodontia. A similar condition is hyperdontia, in which there are more than the usual number of teeth.

[edit] Prevalence

In caucasians, the most common missing teeth are the wisdom teeth (25-35%), the upper lateral incisors (2%) the lower second premolars (3%), or the upper second premolar, with a 4:1 female to male ratio. The prevalance of missing primary teeth is found at 0.1-0.9%, with a 1:1 male to female ratio. Excluding the third molars, missing permanent dentition accounts for 3.5-6.5%.

30-50% of people with missing primary teeth, will have missing permanent teeth .

[edit] Etiology

The cause of isolated missing teeth remains unclear, but the condition is believed to be associated with genetic or environmental factors during development. Missing teeth have been reported in association with increased maternal age, low birth weight, multiple births and rubella virus infection during embryonic life.

Hypodontia is often familial, and can also be associated with genetic disorders such as ectodermal dysplasia or Down syndrome. Hypodontia can also been seen in people with cleft lip and palate.

The Journal of the American Dental Association published preliminary data suggesting a statistical association between hypodontia of the permanent teeth and epithelial ovarian cancer (EOC). The study shows that women with EOC are 8.1 times more likely to have hypodontia than are women without EOC. The suggestion therefore is that hypodontia can serve as a "marker" for potential risk of EOC in women. (Journal of the American Dental Association, vol. 139, p. 163)

Hypodontia is closely associated with environmental factors such as happened in Seveso (Italy) with dioxin ^[1][2][3].

[edit] References

[edit] External links

• JADA article abstract
• Richard R. Welbury Pediatric Dentistry 3rd Edition 2005

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