title: Variations in number and morphology of permanent teeth in 7-year-old Swedish children.
abstract: OBJECTIVE
  To establish the prevalence of numerical and morphological variations of permanent teeth in Swedish 7-year-olds and to accept or reject the hypothesis of a higher prevalence for these conditions in northern Sweden compared to other areas.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  Department of Odontology/Pedodontics, Umeå University, Sweden.
  
  
  METHODS
  A total of 739 healthy Caucasian 7-year-olds residing in the city of Umeå, northern Sweden in 1976. The children were examined clinically and radiographically.
  
  
  RESULTS
  The prevalence of hypodontia (excluding third molars) in girls was 8.4%, in boys 6.5%, and in both sexes combined 7.4%. Of the children with hypodontia, the majority (90.9%) lacked one or two teeth. Lower second premolars were the teeth most frequently missing. The prevalence of hyperdontia was 1.9%; 11 girls and three boys were affected; 78% of the supernumerary teeth were mesiodenses. Of the morphological variations, peg-shaped upper lateral incisors were found in 0.8% of the children, double-formation (gemination) in 0.3%, taurodontism in 0.3% and dens invaginatus in 6.8%. One diagnosis was found in 18% of the children, and in almost 8% of them more than one diagnosis was found.
  
  
  CONCLUSIONS
  The results agree with those obtained in similar populations and are considered representative of this ethnic group. The hypothesis of a genetically determined higher prevalence of numerical and morphological variations in the study population was not verified.
authors: Faculty of Medicine and Odontology, Department of Odontology, Pedodontics, Umeå University, S-901 87 Umeå, Sweden. Birgitta.Backman@odont.umu.se
authors: B
authors: B
authors: Bäckman
authors: Y B
authors: YB
authors: Wahlin
mesh_terms: D000848:Anodontia / Q000453:epidemiology; D002648:Child; D003430:Cross-Sectional Studies; D003719:Dens in Dente / Q000453:epidemiology; D005260:Female; D005671:Fused Teeth / Q000453:epidemiology; D006801:Humans; D008297:Male; D015995:Prevalence; D013548:Sweden / Q000453:epidemiology; D014071:Tooth Abnormalities / Q000453:epidemiology* / Q000473:pathology; D014096:Tooth, Supernumerary / Q000453:epidemiology