More women in Europe and Australia have dental agenesis than their counterparts in North America.
METHODS
Medline and Embase were searched, using the following keywords: "hypodontia", "oligodontia", "anodontia", "agenesis", and "prevalence or incidence". Reference lists from retrieved articles were also examined.


METHODS
For inclusion, an article had to satisfy the following criteria: presence of an English abstract; the sample was representative for the underlying general population; the diagnosis of dental agenesis was based on a radiographic examination; the report presented information on the ethnic background; and the report presented prevalence of agenesis except third molars.


METHODS
Data from Caucasian populations in North America, Australia and Europe were included in a meta-analysis. For the prevalence in African-American, Chinese and Arab groups, only indications could be reported because of a limited number of studies. Multiple-regression analysis was applied to evaluate the influence of chronological age, sample size, continent and year of publication. Statistical significance was established at P<0.05. The prevalence of agenesis per tooth type, affected patients and number of missing teeth per patient was calculated as far as reported in the papers. For the comparison of the prevalence for males and females, the relative risk (RR) was calculated.


RESULTS
The search identified 141 articles, of which 31 met the inclusion criteria. Agenesis differs by continent and gender: the prevalence for both sexes was higher in Europe (males 4.6%; females 6.3%) and Australia (males 5.5%; females 7.6%) than for North-American Caucasians (males 3.2%; females 4.6%). In addition, the prevalence of dental agenesis in females was significantly higher than in males for all three continents, with an RR of 1.37 (95% CI, 1.28-1.45). The mandibular second premolar was the most affected tooth, followed by the maxillary lateral incisor and the maxillary second premolar. Unilateral occurrence of dental agenesis is more common than bilateral occurrence. Bilateral agenesis of maxillary lateral incisors is more common, however, than unilateral agenesis. In most patients, dental agenesis involved only one (48%) or two teeth (35%).


CONCLUSIONS
The prevalence of dental agenesis in Europe and Australia is higher than in North America. The overall prevalence of agenesis in the maxilla is comparable with that in the mandible, but a marked difference was found between both jaws regarding tooth type. Absence of one or two permanent teeth is found in the majority of the subjects with dental agenesis.
Flores-Mir
Carlos
C
Faculty of Medicine and Dentistry Room 4051A, Dentistry/Pharmacy Center, University of Alberta, Edmonton, Alberta, Canada.