Twenty-six bone biopsy specimens, including twenty-four iliac-crest biopsy specimens from twenty-one patients with osteoporosis, were examined for crystallinity by means of x-ray diffraction and for carbon dioxide, citrate, ash, calcium, phosphorus, magnesium, and fluorine by chemical analysis. Nine specimens were obtained prior to fluoride therapy and fifteen specimens after therapy. The findings show that untreated osteoporotic bone has the same crystallinity and chemical composition as normal bone with a low fluoride content. After fluoride therapy there is a significant increase in fluoride concentration from 0.09 to 0.36 per cent, associated with improved crystallinity with ß changing from 0.94 to 0.77 and a decrease in citrate from 2.59 to 1.89 per cent. A slight increase in magnesium content was also observed (from 0.40 to 0.48 per cent). Ash, calcium, phosphorus, and carbon dioxide content remained unchanged.

The results suggest that exposures to high levels of fluoride for periods of one year or less may produce crystallographic and chemical changes in the bone apatite similar to those caused by prolonged use of drinking water containing two to four parts per million of fluoride.