[Cost of fluoridating the public water supply: a study case in the city of São Paulo, Brazil, 1985-2003].

The aim of this study was to estimate the cost of fluoridating the public water supply in the city of São Paulo, Brazil, from 1985 to 2003. Cost calculation for fluoridation of the public water supply used the following: capital cost of initial installation, chemical product (hydrofluosilicic acid), system's operational cost (maintenance, electricity, and human resources), and monitoring fluoride levels. Fluoridation was effective, since there was a decrease of 73% in dental caries in 12-year-olds--mean DMF was 6.47 (6.12-6.82) in 1986, having decreased to 1.75 (1.48-2.92) in 2002. In this age group, 40% of children presented DMF = 0 in 2002. Average cost per inhabitant/year for 2003 was R$ 0.08 (USD 0.03). The accumulated cost for 18 years of implementation and maintenance of the fluoridation system was R$ 1.44 (USD 0.97) per capita.