ESTIMATION OF OPTIMAL CONCENTRATION OF FLUORIDE IN DRINKING-WATER UNDER CONDITIONS PREVAILING IN CHILE

The purpose of this comparative study of caries and dental fluorosis e xperience in Chilean children was to estimate the optimal range of flu oride concentration in tap water under conditions currently prevailing in Chile. The sample included 2431 schoolchildren 7, 12 and 15 years old, life-long residents of five communities with fluoride concentrati ons in their tap water in the range 0.07-1.1 mg/L. The study populatio n received an oral clinical examination including caries experience an d an enamel fluorosis evaluation of the permanent dentition (Dean's sc oring system). For 15-year-old children, the DMFT index changed from 5 .06 to 2.60, and for 12-year-olds it changed from 3.10 to 1.36 when fl uoride water concentration changed from 0.07 to 1.10 mg/L. For 7-year- old children the dmft index correspondingly changed from 3.67 to 1.59. The relationship between DMFT for 12-year-olds and water fluoride con centration was best fitted by a logarithmic function (r(2)=0.98). The Community Fluorosis Index (CFI) was used to assess enamel fluorosis in the study population, and it showed a linear relationship (r(2)=0.983 ) with increasing fluoride concentration of water for the 12-year-old group. Results obtained suggest that under current Chilean conditions, the optimal range of fluoride concentration in potable water should l ie in the 0.5-0.6 mg/L range.