title: Relationship between breastfeeding duration and prevalence of posterior crossbite in the deciduous dentition.
abstract: BACKGROUND
  This cross-sectional retrospective epidemiologic study assessed the relationship between exclusive breastfeeding duration and the prevalence of posterior crossbite in the deciduous dentition.
  
  
  METHODS
  Clinical examinations were performed in 1377 Brazilian children (690 boys, 687 girls), 3 to 6 years old, from 11 public schools in São Paulo, Brazil. Based on questionnaires answered by the parents, the children were classified into 4 groups according to the duration of exclusive breastfeeding: G1, never (119 subjects); G2, less than 6 months (720 subjects); G3, 6 to 12 months (312 subjects); and G4, more than 12 months (226 subjects). The statistical analyses included the chi-square test (P <0.05) and the odds ratio.
  
  
  RESULTS
  The posterior crossbite was observed in 31.1%, 22.4%, 8.3%, and 2.2% of the children, in groups G1, G2, G3, and G4, respectively. The results showed a statistically significant relationship between exclusive breastfeeding duration and the prevalence of posterior crossbite.
  
  
  CONCLUSIONS
  Children who were breastfed for more than 12 months had a 20-fold lower risk for the development of posterior crossbite compared with children who were never breastfed and a 5-fold lower risk compared with those breastfed between 6 and 12 months.
authors.affiliation: Department of Orthodontics, University of São Paulo City, Universidade Cidade de São Paulo, São Paulo, Brazil. henrimenezeskobayashi@yahoo.com
authors.forename: Henri Menezes
authors.initials: HM
authors.lastname: Kobayashi
authors.forename: Helio
authors.initials: H
authors.lastname: Scavone
authors.forename: Rívea Inês
authors.initials: RI
authors.lastname: Ferreira
authors.forename: Daniela Gamba
authors.initials: DG
authors.lastname: Garib
mesh_terms: D001903:Bottle Feeding / Q000009:adverse effects*; D001938:Brazil / Q000453:epidemiology; D001942:Breast Feeding / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000453:epidemiology* / Q000209:etiology*; D015995:Prevalence; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013997:Time Factors; D014094:Tooth, Deciduous