<unk>  is less common in the primary dentition with reported prevalence rates ranging from 0.5% in Icelandic population to 2.4% in Japanese population. In the primary dentition the teeth reported as most likely to be missing are the lateral incisors, both maxillary and mandibular. If a deciduous tooth is missing this will increase the risk of an absent successor. In the permanent dentition third molars are most commonly absent and one study found prevalence rates of between 20 and 22%. When third molars are ignored the prevalence rate for each tooth varies from study to study. In Caucasian studies mandibular second premolars and maxillary lateral incisors are most often absent. Several UK studies have found the lower second premolar to be most commonly absent. Studies from Asian populations report that the mandibular incisor is most commonly absent. A higher prevalence of<unk>  in females has been reported, 3:2. The most extensive studies have been in Caucasian populations and suggest a prevalence of 4-6%. One study looked at 33 previous studies with a sample size of 127000 and concluded that the prevalence of<unk>  in the permanent dentition varied between continents, racial groups and genders. In the white European population they suggested a prevalence of 4.6% in males and 6.3% in females. In an African-American sample they found this to be 3.2% in males and 4.6% in females. The same study found that in the permanent dentition the most likely teeth to be missing and the frequency of these missing teeth was: * Mandibular second premolar 3% * Maxillary lateral incisor 1.7% * Maxillary second premolar 1.5% * Mandibular central incisor 0.3%
Hypodontia
Hyperdontia
Anodontia
Maxillary hypoplasia
Micrognathism
Hemifacial microsomia
Iniencephaly
Elfin facies