The effect of water fluoridation and social inequalities on dental caries in 5-year-old children.

BACKGROUND: Many studies have shown that water fluoridation dramatically reduces dental caries, but the effect that water fluoridation has upon reducing dental health inequalities is less clear. The aim of this study is to describe the effect that water fluoridation has upon the association between material deprivation and dental caries experience in 5-year-old children. METHODS: It is an ecological descriptive study of dental caries experience using previously obtained data from the British Association for the Study of Community Dentistry's biennial surveys of 5-year-old children. This study examined the following data from seven fluoridated districts and seven comparable non-fluoridated districts in England: 1) dental caries experience using the dmft (decayed, missing, filled teeth) index; 2) the Townsend Deprivation Index of the electoral ward in which the child lived; 3) whether fluoride was present at an optimal concentration in the drinking water or not. RESULTS: A statistically significant interaction was observed between material deprivation (measured by the Townsend Deprivation Index) and water fluoridation (P < 0.001). This means that the social class gradient between material deprivation and dental caries experience is much flatter in fluoridated areas. CONCLUSION: Water fluoridation reduces dental caries experience more in materially deprived wards than in affluent wards and the introduction of water fluoridation would substantially reduce inequalities in dental health.