[Antioch]

Fluoride is essential to mineralization, but as an ultra trace element. Thats why dental health IS worse in non-flouridated areas. Fluoride requirements are not in the category of zinc, selenium or manganese, but rather in amounts as boron, nickel or vanadium in the body. The deletorious health effects of fluoride are due to overexposure beyond the body's needs (resulting from cumulative effects of water, toothpastes, dental gels etc.)

[tongass kid]

I believe you may be trying to define the optimum concentration of fluoride in the water. Unfortunately, some areas of the country have naturally occurring fluoride far beyond the optimum. Anyone drinking from a well or non public water supply should consider testing the water for various items including fluoride.