[Fluoride therapy of osteoporosis]

The effects of fluoride on bone seem to be dose- and time dependent: The optimized exposition to fluorides over decades might serve the bone as a trace element in a similar manner like in the case of caries prophylaxis of the teeth. This infers the potential that lifelong optimized fluoride supply (e.g. via drinking water) could serve as a general osteoporosis prophylaxis. This is to be differentiated from the use of much higher doses of fluoride as a pharmacological stimulus of the osteoblasts. In fact, such fluoride treatment increases the mass of trabecular bones, as demonstrated by histological and osteodensitometric techniques. In parallel during the last more than 20 years many retrospective studies yielded results indicating a decrease in osteoporotic fractures during fluoride treatment. However, the first two randomized double blind studies from the USA do not show this decrease in vertebral fracture incidence. The reasons for this could be due to the study design (unchanged high dosage over four years in contrast to the commonly used individual adaptation of dosage and time); however, also the earlier positive results could be an error. Therefore, new studies are mandatory, but until their results are available, the continuation of fluoride treatment of established osteoporosis is justified, competent surveillance being a prerequisite.