Potential Reduction in Caries from Fluoridating a UK City

Objective: It has been postulated that in areas where the mean dmft at 5-years is 2.0 or more (especially if there are districts where it exceeds 2.6), and where the water treatment plant serves populations of at least 200,000, water fluoridation is likely to be cost-effective. A major city in the West of England (population 410,500) was investigated, in the light of these criteria, to ascertain whether it would be a potential, suitable candidate for an operable and efficient fluoridation scheme. Method: The 13 out of 35 city wards with the highest indexes of multiple deprivation (IMD) and/or highest mean dmft of 5-6-year-olds (recorded in a census survey in 2005/6), and 7 similarly deprived wards in neighbouring urban districts sharing the city's water supply, were targeted. The water supply network and water treatment works serving these areas were ascertained. The mean IMD score, and aggregated, weighted mean values for dmft and caries prevalence were then compared with scatter diagrams of mean caries scores plotted against IMD for 33 fluoridated (F) and 213 non-fluoridated (NF) health districts in England. Estimates of the potential reduction in mean dmft and increase in proportions of caries-free 5-6-year-old children in the city and environs from receiving fluoridated water from birth were obtained. Results: Mean dmft of 5-6-year-olds in the 20 wards was 2.08 (95% CI 1.95, 2.22) and caries prevalence 49% (95% CI 47%, 52%). In 3 wards mean dmft > 2.6. Population of the selected wards was ~210,800 and mean IMD score 32.85. As a conservative estimate, after 5 years a caries reduction of at least 45% could be expected with a gain of at least 12% in the proportion of caries-free 5-6-year-olds. Conclusions: The data indicate that the city and environs meet the criteria for fluoridation to be a potentially cost-effective strategy.