Social gradient in dental caries among adolescents in Sri Lanka.

The aim of the present study was to assess the social inequality in dental caries among adolescents in Sri Lanka. A total of 1,225 15-year-olds were selected using a stratified cluster sampling technique from schools in the Colombo district. The data were collected by means of an oral examination and questionnaires to both children and their parents. There were statistically significant inverse gradients between caries prevalence, caries experience (DMFS) and all five socio-economic indicators considered. Maternal education and family affluence emerged as significant predictors of dental caries. The magnitude of social inequality in dental caries was assessed using the slope index of inequality (SII) and the concentration index based on the concentration curve. SII for all socio-economic indicators were negative and, except in relation to father's occupation, they were statistically significant. With the socio-economic groups ordered from the lowest to the highest, a negative SII indicates that caries experience decreased with improving socio-economic status. The concentration index for DMFS was negative (-0.111) and statistically significant, indicating disproportionate concentration of dental caries among the poor children. In conclusion, this study has shown the existence of a social gradient with respect to dental caries among adolescents in Sri Lanka and it also illustrates the use of SII and concentration index as tools to determine the magnitude of social inequality in dental caries.