title: The oral health environment and the equal environment assumption (EEA) among 1-8-year-old  twins.
abstract: OBJECTIVE
  The purpose of the present study was to describe the oral health environment in preschool children and to  examine the extent to which paired twins experience the same oral health environment.
  
  
  METHODS
  In  collaboration with The Medical Birth Registry of Norway (MBRN) 100 twin families who participated in the Norwegian Mother  and Child Cohort, were invited to take part in ongoing studies on oral health. Participating twin families lived in Oslo and the  surrounding counties of the capital. The age range of the participating twins was 1-8 years. A clinical examination took place  at The Institute of Clinical Dentistry, University of Oslo in 2008.  The oral health environment was measured in two ways: 1)  Interview. Mothers were interviewed by trained interviewers about oral health related habits of each of the twins. 2) Weekend  diet log. Parents listed 84 different deserts, ice cream, sweets, cakes, cookies, fruits, snacks, and biscuits for each twin that  were consumed on  during the weekend. The statistical analyses comprised frequency distributions of the environmental  variables and correlations between the variables within the pair of twins.
  
  
  RESULTS
  The results showed a parental  involvement in early tooth brushing and also an indication of tooth brushing not always being easy. Use of fluoride  toothpaste started early, and two thirds of the children also used fluoride tablets. Use of pacifier was prevalent; the duration  of use of pacifier and feeding bottle was relatively long. Nearly 75% of the parents indicated that they had no problems  relatively to the twins' meals, and 53% mentioned that the twin pairs were different with regard to meals. Nearly  70% of the kindergartens had a clear health profile. The correlations varied between r = 0.45 and 1.00.
  
  
  CONCLUSIONS
  The children in the present work were young, and the detailed information in this paper therefore adds to the  knowledge of parental involvement in children's oral health. Generally the findings indicate a high level of involvement from  the parents in the oral health environment at home. Altogether the results showed that the assumption of identical oral health  environment cannot be supported by these data.
authors.affiliation: Institute of Clinical Dentistry, Section of Community Dentistry and Department of Prosthodontics, University of Oslo, Faculty of Dentistry, Norway. dholst@odont.uio.no
authors.forename: D
authors.initials: D
authors.lastname: Holst
authors.forename: J A
authors.initials: JA
authors.lastname: Aas
mesh_terms: D001903:Bottle Feeding; D002327:Cariostatic Agents / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004326:Drinking; D004435:Eating; D005247:Feeding Behavior; D005260:Female; D005386:Fingersucking; D005459:Fluorides / Q000008:administration & dosage / Q000627:therapeutic use; D015438:Health Behavior; D006801:Humans; D007223:Infant; D008297:Male; D009034:Mother-Child Relations; D009909:Oral Health; D041361:Pacifiers; D013607:Tablets; D014078:Tooth Eruption; D014099:Toothbrushing; D014100:Toothpastes / Q000627:therapeutic use; D014427:Twins
chemical_list: D002327:Cariostatic Agents; D013607:Tablets; D014100:Toothpastes; D005459:Fluorides