Material and method: Four hundred and seventy-two children from 13 different schools were divided into 4 groups, according to the waters' fluoride concentrations (A °Ü 1.0 mg/L, B = 1.1-2.0 mg/L, C = 2.1 ¨C 3.8 mg/L and D = 7.6 mg/L). Clinical examinations were made under field conditions, and dental fluorosis on buccal surfaces of all teeth was recorded, using the Thylstrup/ Fejerskov index (TFI).
Results: 1. The prevalence of dental fluorosis in deciduous teeth varied from 6.2% to 96.6% according to the fluoride concentration of the drinking waters. The differences of mean TF-scores between groups A and B, and between C and D were statistically significant (p<0.001). 2 No statistically significant difference was observed between the genders, as to prevalence and severity of dental fluorosis. 3. In the low-fluoride group (Group A), no difference was observed in mean TF score between the 7 and 8 year-olds. In groups B and C, however, TF-scores tended to be higher in 7 year-olds than in 8 year-olds. The age-related difference was statistically significant in group C (p=0.0319). In group D, the tendency was reversed and the TF-score in 8 year-olds was higher than that of 7 year-olds. 4. The second deciduous molars were most severely affected by dental fluorosis. Disregarding group A, TF-scores 3-4 were most frequently recorded. 5. Dental fluorosis was symmetrically distributed in both jaws. More than 71% of the pared homologous teeth in maxilla or mandible exhibited the same TF-score.
Conclusion: In areas depending upon water with fluoride concentrations higher than 1.0 mg/L, dental fluorosis is prevalent also in deciduous teeth.