title: The prevalence of incisor hypomineralisation and its relationship with the prevalence of molar incisor hypomineralisation.
abstract: OBJECTIVE
  To establish the prevalence of incisor hypomineralisation (IH) in a cohort of 12-year-old children in Northern England and to relate the prevalence to gender, socioeconomic status, and the prevalence of molar incisor hypomineralisation (MIH).
  
  
  METHODS
  The study population comprised 12-year-old children participating in the 2008-2009 National Dental Epidemiological Programme in five regions in Northern England. Participating dentists were trained and calibrated in the use of the modified Developmental Defects of Enamel Index. Children were examined at school under direct vision with the aid of a dental mirror. First permanent molars and incisors were recorded for the presence and type of enamel defects greater than 2 mm. A diagnosis of MIH was ascribed to any child with a demarcated defect in any first permanent molar. A diagnosis of IH was ascribed to any child with a demarcated defect in an incisor but with molar sparing.
  
  
  RESULTS
  3,233 children were examined. The prevalence of IH was 11.0 % (95 % CI 11.0-12.2 %). There was a strong positive correlation between the prevalence of MIH and IH in different regions which reached significance (r = 0.9, p = 0.037) according to Spearman's rho test of correlation. There was a similar pattern of prevalence in the different socioeconomic quintiles although this correlation did not reach significance. The most common teeth affected in IH were the maxillary central incisors, followed by the maxillary lateral incisors and followed by the mandibular incisors. There was no difference in the prevalence of IH by gender.
  
  
  CONCLUSIONS
  The prevalence of IH was 11.0 %. The variation of prevalence between regions and socioeconomic groups and the distribution of lesions in the teeth were very similar to observations seen in MIH children from the same cohort.
authors.affiliation: Department of Child Dental Health, Leeds Dental Institute, Clarendon Way, Leeds, LS2 9LU, UK, r.c.balmer@leeds.ac.uk.
authors.forename: R
authors.initials: R
authors.lastname: Balmer
authors.forename: K J
authors.initials: KJ
authors.lastname: Toumba
authors.forename: T
authors.initials: T
authors.lastname: Munyombwe
authors.forename: J
authors.initials: J
authors.lastname: Godson
authors.forename: M S
authors.initials: MS
authors.lastname: Duggal
mesh_terms: D002648:Child; D015331:Cohort Studies; D003743:Dental Enamel / Q000002:abnormalities; D003744:Dental Enamel Hypoplasia / Q000145:classification / Q000453:epidemiology*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D007180:Incisor / Q000002:abnormalities*; D008297:Male; D008963:Molar / Q000002:abnormalities; D015995:Prevalence; D012737:Sex Factors; D012923:Social Class