The association between area deprivation and dental caries in groups with and without fluoride in their drinking water.

In order to determine the association between social background and dental caries for subjects living in areas with and without fluoride in the drinking water, lifetime residents from Anglesey (0.7 mg/l F-, n = 196) and Chester/Bala (< 0.1 mg/l F-, n = 267) were examined. The mean age overall was 14.1 (+/- 0.3) years. For the Anglesey group, when differences in material deprivation were controlled, the mean DMFS was 2.9 compared with 4.3 in Chester/Bala, a difference of 33 per cent. Using multiple linear regression it was found that there was no interaction between material deprivation and water fluoridation. This suggested that absolute differences in dental caries between these areas with and without fluoride in the drinking water were similar for different strata of deprivation. It follows that percentage reductions in dental caries resulting from fluoridation of water supplies tended to be less in deprived than non deprived groups.