The aim of the present study was to evaluate the fluoride levels in public water supply in São Luís island, Maranhão State, Brazil, during the month of October of 2006. A stratification sampling was applied, considering the water treatment station (06) and the different districts (46). For fluoride analysis it was used a specific ion electrode. The fluoride concentration varied for 0.05 to 0.84 ppm. Only one water treatment station (Italuís) presented an ideal concentration of fluoride. It was concluded that the fluoride levels need adjustments, evidencing that it is essential an external control for monitoring of those levels in public water supply of São Luis.
Dental caries; Fluoridation; Water
