title: Congenitally missing permanent mandibular incisors and their association with missing primary teeth in the southern Chinese (Hong Kong).
abstract: A radiographic survey of a random sample of 454 girls aged 5.9 +/- 0.5 yr and 521 boys aged 5.8 +/- 0.4 y was undertaken to establish data on the incidence of congenitally missing mandibular incisor teeth amongst the Southern Chinese and to compare these figures with those of a similar previous study of 12-yr-olds so to eliminate factors such a trauma or extractions which may have artificially inflated the 12-yr-old incidence data. The proportion of 5-yr-old girls and boys affected by hypodontia in the permanent mandibular incisor region was 0.086 and 0.046 respectively (a significant difference between sexes, P < 0.02), compared with 0.047 and 0.034 for the 12-yr-olds (a non-significant difference) so other factors must have contributed to the discrepancy between the two groups of children. A very strong correlation (P < 10(-25)) between missing primary and missing permanent mandibular incisors is present in this group, and this has implications for prognosis and treatment planning. A fundamental developmental defect is implied.
authors.affiliation: Department of Children's Dentistry and Orthodontics, University of Hong Kong, Prince Philip Dental Hospital.
authors.forename: P J
authors.initials: PJ
authors.lastname: Davis
authors.forename: B W
authors.initials: BW
authors.lastname: Darvell
mesh_terms: D000367:Age Factors; D000848:Anodontia / Q000453:epidemiology*; D002675:Child, Preschool; D002681:China / Q000208:ethnology; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007180:Incisor / Q000002:abnormalities*; D008297:Male; D008334:Mandible; D012737:Sex Factors; D014094:Tooth, Deciduous / Q000002:abnormalities*