OBJECTIVE To determine the total fluoride dose to which children were exposed during the critical age of developing dental fluorosis, in an optimally fluoridated region, having diet (liquids and solids) and dentifrice as fluoride sources. METHODS For the pilot study, 39 children (aged 20 to 30 months) were selected from a day care center in Piracicaba, Brazil. They drank and ate food prepared with fluoridated water. To determine the total dose of fluoride exposure, duplicate-plate samples and products from tooth brushing were collected for two consecutive days, in four periods of the year. Fluoride was determined using an ion specific electrode. A 5% level of significance variance analysis (Anova) was carried out. RESULTS Children were exposed to a total fluoride dose of 0.090 mg/day/kg of body weight, of which 45% came from the diet and 55% from dentifrice. CONCLUSIONS Assuming 0.07 mg/kg as a threshold value of fluoride systemic exposure, children were exposed to a risk dose for dental fluorosis. Thus, measures to reduce fluoride intake at the studied age range would be recommended. Reducing the amount of dentifrice used for tooth brushing seems to be the best measure, given the risk/benefits of fluoride use from the public health perspective.