Rik

The effects of fluoride are both topical and systemic.  Systemic effects are  shown in the mild to very mild dental fluorosis.  This level of dental fluorosis is barely detectable and causes no adverse effect on cosmetics, form, function, or health of teeth.  As Kumar, et al. have demonstrated mildly fluorosed teeth to be more decay resistant, many consider this effect to not even be undesirable, much less adverse.  Dental fluorosis can only occur systemically. 

—-The Association Between Enamel Fluorosis and Dental Caries in U.S. Schoolchildren Hiroko Iida, DDS, MPH and Jayanth V. Kumar, DDS, MPH

Additionally, saliva with fluoride incorporated, constantly bathes  the teeth in a low concentration of fluoride all throughout the day, a very effective means of dental decay prevention. Incorporation of fluoride into saliva occurs systemically.

If you have any valid evidence of "harm" from optimal level fluoride, feel free to present it at any time.

Steven D. Slott, DDS