Dental caries and microbial acid production in twins.
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.
Bretz
W A
WA
School of Dental Medicine, University of Pittsburgh, 3501 Terrace Street, Pittsburgh, PA 15261, USA. wab2@pitt.edu
Corby
P M A
PM
Hart
T C
TC
Costa
S
S
Coelho
M Q
MQ
Weyant
R J
RJ
Robinson
M
M
Schork
N J
NJ
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
D000143:Acids