Variation of caries frequency with socio-economic background in unselected and extreme groups of 14-year old children in Malmö.

The purpose of the present investigation was to find out whether any correlation exists between socio-economic factors and caries frequency in unselected and extreme groups of 14-year old school children in Malmö. The material consisted of 360 randomly selected 14-year old school children in Malmö (1969) and their parents. The number of DF-surfaces was obtained from the records of the school dental service. Data on the parents' occupation and gross incomes in 1969 were obtained from the tax office in Amlmö. Extreme groups were obtained by chosen those 10% with the highest caries frequency (H'-group) and a corresponding group with the lowest frequency of caries (L'-group). These two subgroups were compared with a selection of 14-year old school children with high (H-group) and low (L-group) caries frequency, which have been analysed earlier in respect of socio-economic background. No significant correlation was found between socio-economic factors and caries frequency in the non-stratified selection. H'-group and L'-group, on the other hand, showed marked differences in socio-economic background. Compared with the H-group, the H'-group showed a higher number of DF-surfaces. This difference was due to variations in distribution of caries between different schools but was not clearly correlated to socio-economic factors. The differences in socio-economic distribution between H'-group and H-group like between L'-group and L-group were not found to be significant. The findings mean that the conclusions drawn regarding socio-economic factors and dental care regarding H- and L-group also can be regarded as representative of schoolchildren with extremely high and low caries frequency, respectively.