URINARY FLUORIDE LEVELS AND PREVALENCE OF DENTAL FLUOROSIS IN 3 BRAZILIAN CITIES WITH DIFFERENT FLUORIDE CONCENTRATIONS IN THE DRINKING-WATER

Urine samples from three daytime periods were collected from 545 5-50- year-old residents of three different Brazilian cities: Garca had fluo ridated drinking water since 1973, Bauru since 1975 and Itapolis was n ot fluoridated. Dental fluorosis was examined in 985 5-24-year-olds us ing the Thylstrup-Fejerskov index (TF). The subjects were asked to est imate their daily intake of liquids and frequency of beverage consumpt ion. The analysis of 94 water samples showed high variations in the fl uoride content of the drinking water. The mean fluoride concentration of the water samples in Garca was 0.9 mg/L (range 0.75-1.2), in Bauru 0.64 mg/L (range 0.01-1.3), and in Itapolis 0.02 mg/L. Mean urinary fl uoride concentration was 1.31 mg/L (s 0.61) in Garca, 0.88 mg/L (s 0.4 9) in Bauru, and 0.39 mg/L (s 0.21) in Itapolis. Self-reported daily l iquid intake was not related to urinary fluoride concentration. The me an prevalence of fluorosis was 13.3% in Garca, 6.8% in Bauu, and 1.7% in Itapolis, with mainly categories TF 1 and TF 2 being recorded. Subj ects with dental fluorosis tended to show a higher mean urinary fluori de concentration but the difference was not statistically significant. The study showed that fluoride exposure measured by urinary fluoride excretion was within the range expected for the level of fluoride conc entration in the drinking water. However, enamel fluorosis tended to b e markedly lower than expected. This study revealed that fluoride leve ls in the two cities with fluoridated drinking water were variable. To optimise anticaries benefits and minimise the risk of fluorosis great er control of the fluoride dosing of the drinking water is required.