Inequalities in dental health: An ecological analysis of the interaction between the effects of water fluoridation and social deprivation on tooth decay in children living in England

Abstract

Oral health in England has improved considerably in recent years but continues to show a strong inequalities gradient. This study was aimed at investigating variations in dental decay and relation to social deprivation and local water fluoridation. An ecological analysis using the 2007 and 2008 National Dental Epidemiology Programme survey of 5 year old children in England. Postcode of residence was mapped to census lower super output area (LSOA). LSOAs were assigned a national deprivation quintile and a fluoridation category based upon therapeutic level of 1 mg/L. Multiple logistic regression was applied to determine independent influences on tooth decay. Analysis of covariance (ANCOVA) was used to investigate interactions between fluoridation and deprivation on the mean levels of dental caries. Analysis is based on 142,030 clinical dental examinations, representing 25% of estimated population of 5 year olds in England. Overall, 31% of children had at least one decayed missing or filled tooth (dmft). Multiple logistic regression showed that children living in the most deprived areas were three times more likely to experience tooth decay than those living in affluent areas; whereas children living in fluoridated areas were 1.5 times less likely to have dmft than those living in non-fluoridated areas. Therefore, although both are independently significant, living in the most deprived quintile of social deprivation doubled the impact on the likelihood of dental decay compared to non-fluoridation. ANCOVA showed a strong gradient of increasing mean dmft with increasing social deprivation in both water-fluoridated and non-fluoridated areas, with 3 times more dental decay in more deprived areas than in more affluent areas. In all deprivation quintiles, children living in fluoridated areas have significantly (p < 0.001) lower mean dmft than those living in equivalent deprivation with no water fluoridation. Fluoridated drinking water may moderate dental caries; however, socioeconomic deprivation has a stronger influence on dental decay than local fluoridation of water.