title: The relationship between tooth wear in the primary and permanent dentitions.
abstract: OBJECTIVE
  To evaluate the relationship between tooth wear in primary and permanent dentition in 7 to 10-year-old school children, in 2007.
  
  
  METHODS
  An epidemiological cross-sectional survey was conducted by trained, calibrated examiners, using the dental wear index (DWI). The cluster sample consisted of 764 children (382 boys, 382 girls) attending 4 public schools selected in different regions of the city. The DWI was proposed to evaluate primary and permanent teeth, coded as letters and numbers, respectively. Data were collected via clinical examinations performed outdoors under natural light, following the WHO recommendations and using a dental mirror and probe. Proportions and confidence intervals were used to describe the prevalence of dental wear. The Mann-Whitney and the Odds Ratio (OR) tests were used to compare the tooth wear prevalence between primary and permanent teeth according to surface (p < 0.05).
  
  
  RESULTS
  The 7 to 10-year-old school children presented 16% tooth wear. The tooth wear was mostly seen on the occlusal/incisal surfaces (47%), involving enamel or enamel-dentine. Tooth wear in primary teeth was found in canines and molars (93%) and in permanent teeth in molars (34%). There was significant difference between primary and permanent teeth (p < 0.001) and dental wear in primary teeth was greater in boys than in girls (p = 0.02) but not in permanent teeth.
  
  
  CONCLUSIONS
  The results suggest that 7 to 10-year-old children with tooth wear in primary teeth had more chances of developing tooth wear in permanent dentition. However, the findings of this study are not conclusive as the associations described are not causal.
authors.affiliation: Department of Pediatric Dentistry, Orthodontics and Public Health, Bauru School of Dentistry, University of São Paulo, Brazil. shcperes@usp.br
authors.forename: S H C
authors.initials: SH
authors.lastname: Sales-Peres
authors.forename: A C
authors.initials: AC
authors.lastname: Sales-Peres
authors.forename: J A
authors.initials: JA
authors.lastname: Marsicano
authors.forename: C A P
authors.initials: CA
authors.lastname: Carvalho
authors.forename: F S
authors.initials: FS
authors.lastname: Carvalho
authors.forename: J R P
authors.initials: JR
authors.lastname: Lauris
authors.forename: A
authors.initials: A
authors.lastname: Sales-Peres
mesh_terms: D001938:Brazil / Q000453:epidemiology; D002648:Child; D016001:Confidence Intervals; D019229:Dentition, Permanent; D005260:Female; D006801:Humans; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D012306:Risk; D018709:Statistics, Nonparametric; D057085:Tooth Wear / Q000453:epidemiology*; D014094:Tooth, Deciduous; D014505:Urban Population