title: Dental caries and microbial acid production in twins.
abstract: OBJECTIVE
  To determine the relative contribution of genetic and environmental stimuli on dental caries traits and microbial acid production in a twin model.
  
  
  METHODS
  Dental caries examinations and microbial acid production assays were performed on 388 pairs of twins 1.5-8 years old from the city of Montes Claros, Brazil. Genotyping 8 polymorphic DNA markers determined zygosity. Caries exams followed NIDCR criteria modified to distinguish white spot lesions from cavitated lesions. Surface-based caries prevalence rates (SBCPR) were computed and lesion severity was determined by a weighted index (LSI). Biofilm samples were collected from the tongue using a lactic acid indicator swab. Assay scores were categorized based on acid formation as 1 = low, 2 = medium, and 3 = high. Heritability analyses were performed using the SOLAR software package.
  
  
  RESULTS
  Heritability estimates for SBCPRs, LSI and for microbial acid production were H = 76.3 (p < 0.001), H = 70.6 (p < 0.001), H = 16.2 (p = 0.0078), respectively. Treating microbial acid production as a covariate in the SBCPR and LSI models did not significantly alter the heritability estimates, i.e. H = 76.5 (p < 0.001) and H = 70.8 (p < 0.001), respectively.
  
  
  CONCLUSIONS
  These results suggest that variation in dental caries surface traits has a significant genetic contribution and that microbial acid production is modulated by the environment.
authors.affiliation: School of Dental Medicine, University of Pittsburgh, 3501 Terrace Street, Pittsburgh, PA 15261, USA. wab2@pitt.edu
authors.forename: W A
authors.initials: WA
authors.lastname: Bretz
authors.forename: P M A
authors.initials: PM
authors.lastname: Corby
authors.forename: T C
authors.initials: TC
authors.lastname: Hart
authors.forename: S
authors.initials: S
authors.lastname: Costa
authors.forename: M Q
authors.initials: MQ
authors.lastname: Coelho
authors.forename: R J
authors.initials: RJ
authors.lastname: Weyant
authors.forename: M
authors.initials: M
authors.lastname: Robinson
authors.forename: N J
authors.initials: NJ
authors.lastname: Schork
mesh_terms: D000143:Acids / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003731:Dental Caries / Q000453:epidemiology / Q000235:genetics* / Q000382:microbiology*; D003732:Dental Caries Activity Tests / Q000379:methods; D004200:Diseases in Twins / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D016014:Linear Models; D008297:Male; D019655:Quantitative Trait, Heritable
chemical_list: D000143:Acids