CONCLUSIONS: A suitable trade-off between caries and fluorosis appears to occur around 0.7 ppm F. Data from this study suggest that a reconsideration of the policies concerning the most appropriate concentrations for water fluoridation might be appropriate for the United States.
J Public Health Dent. 1997 Summer;57(3):136-43.
Dental caries and dental fluorosis at varying water fluoride concentrations.
Heller KE , Eklund SA, Burt BA.