title: Prevalence of hypodontia in nine- to fourteen-year-old children who attended the Mashhad School of Dentistry.
abstract: BACKGROUND
  Hypodontia is defined as the congenital absence of one or a few teeth, and is also the most common anomaly in dental development. This condition occurs either individually or as part of the symptoms of a syndrome, and it is more common in permanent teeth than in deciduous teeth, reporting a prevalence of between 1.6 and 9.6%.
  
  
  OBJECTIVE
  The objective of this study is to investigate the prevalence of hypodontia for permanent teeth in nine- to 14-year-old children who attended the Mashhad School of Dentistry in 2007.
  
  
  METHODS
  We conducted this descriptive, analytical, cross-sectional study, to determine the mentioned aims.
  
  
  METHODS
  In this descriptive, cross-sectional study, panoramic radiographs belonging to 600 children (351 girls and 249 boys), aged nine to 14 years, were available for examination. All related findings were recorded in the respective forms.
  
  
  METHODS
  The data were processed using Exact and Chi-square tests.
  
  
  RESULTS
  The prevalence of hypodontia in the girls was 9.2%, in the boys 8.8%, and in both sexes combined 9%. The most and the least frequent cases of absent teeth were the mandibular second premolars and the maxillary central incisor (only one child), respectively. The most commonly absent teeth were the mandibular second premolars, the maxillary lateral incisors, the mandibular central incisor, and the maxillary second premolars, in that order.
  
  
  CONCLUSIONS
  This study showed a high frequency of hypodontia among the understudied population. Thus, due to the complicated treatment, accurate examination of children for on-time diagnosis of this developmental anomaly is crucial.
authors.affiliation: Department of Pediatric Dentistry, Dental School and Dental Research Center of Mashhad University of Medical Sciences, Iran.
authors.forename: Behgat-al-molok
authors.initials: BA
authors.lastname: Ajami
authors.forename: Mahboobeh
authors.initials: M
authors.lastname: Shabzendedar
authors.forename: Maryam
authors.initials: M
authors.lastname: Mehrjerdian
mesh_terms: D000293:Adolescent; D000848:Anodontia / Q000453:epidemiology*; D001641:Bicuspid / Q000002:abnormalities; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007180:Incisor / Q000002:abnormalities; D007194:India / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D011862:Radiography, Panoramic / Q000706:statistics & numerical data