Exposure to water fluoridation and caries increment.
OBJECTIVE
The objective of this cohort study was to examine the association between exposure to water fluoridation and the increment of dental caries in two Australian states: Queensland (Qld)--5 per cent fluoridation coverage; and South Australia (SA)--70 per cent fluoridation coverage.


METHODS
Stratified random samples were drawn from fluoridated Adelaide and the largely non-fluoridated rest-of-state in SA, and fluoridated Townsville and non-fluoridated Brisbane in Qld.


METHODS
Children were enrolled between 1991 and 1992 (SA: 5-15 yrs old, n = 9,980; Qld: 5-12 yrs old, n = 10,695). Follow-up caries status data for 3 years (+/- 1/2 year) were available on 8,183 children in SA and 6,711 children in Qld.


METHODS
Baseline data on lifetime exposure to fluoridated water, use of other fluorides and socio-economic status (SES) were collected by questionnaire, and tooth surface caries status by dental examinations in school dental service clinics.


RESULTS
Higher per cent lifetime exposure to fluoridated water (6 categories: 0;1-24; 25-49; 50-74; 75-99; 100 per cent) was a significant predictor (ANOVA, p < 0.01) of lower annualised Net Caries Increment (NCI) for the deciduous dentition in SA and Qld, but only for Qld in the permanent dentition. These associations persisted in multiple linear regression analyses controlling for age, gender, exposure to other fluorides and SES (p < 0.05).


CONCLUSIONS
Water fluoridation was effective in reducing caries increment, even in the presence of a dilution effect from other fluorides. The effect of fluoridated water consumption was strongest in the deciduous dentition and where diffusion of food and beverages from fluoridated to non-fluoridated areas was less likely.
Spencer
A J
AJ
Australian Research Centre for Population Oral Health, School of Dentistry, The University of Adelaide, South Australia. john.spencer@adelaide.edu.au
Armfield
J M
JM
Slade
G D
GD
D000293:Adolescent; D000367:Age Factors; D002327:Cariostatic Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology*; D005260:Female; D005457:Fluoridation / Q000706:statistics & numerical data*; D005459:Fluorides / Q000627:therapeutic use; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011793:Queensland / Q000453:epidemiology; D012737:Sex Factors; D012923:Social Class; D013021:South Australia / Q000453:epidemiology; D014094:Tooth, Deciduous / Q000473:pathology
D002327:Cariostatic Agents; D005459:Fluorides