Optimal fluoride concentration in drinking water for balancing dental caries prevention and fluorosis control in Jinan, China.

Fluoride in drinking water plays a dual role in dental health, where both excessive and insufficient intake present significant public health challenges. This cross-sectional study analyzed data from 3,980 children aged 8 to 12 years in Jinan, Shandong Province, China, collected in 2019 and 2024. The aim was to determine the optimal fluoride concentration in drinking water that balances the prevention of dental caries with the control of dental fluorosis. The associations between dental health outcomes and water fluoride concentrations were examined using combined data from the two independent cross-sectional surveys conducted in 2019 and 2024. The results indicated that each 1 mg/L increase in fluoride concentration was associated with a 1,246% (OR: 13.46, 95%CI: 8.30, 21.84) increase in the risk of dental fluorosis. Conversely, the risk of dental caries exhibited a U-shaped association, with fluoride levels ranging from 0.5 to 1.0 mg/L linked to a lower risk of dental caries (OR: 0.85, 95%CI: 0.74, 0.97) while also being associated with a controlled prevalence of dental fluorosis (OR: 2.51, 95%CI: 1.88, 3.35). These findings suggest that establishing a fluoride concentration range of 0.5 to 1.0 mg/L is optimal for balancing the prevention of dental caries and the control of dental fluorosis.