Fluoride and bone health.

This paper reviews some of the studies related to the effect of fluoride on the skeletal system of humans and outlines the knowns and unknowns of fluoride and bone health. Current research indicates that, in large enough doses, fluoride stimulates bone formation by osteoblastic stimulation, increases bone formation earlier and to a larger extent in trabecular bone compared to cortical bone, and increases spinal bone density. There is controversy, however, concerning the efficacy of fluoride as a therapeutic agent in the treatment of osteoporosis. Some clinical studies have found a reduction in vertebral fracture rates while others have not. To date, only ecologic studies have been conducted on the association between water fluoridation and hip fractures. The inability of ecologic studies to control for confounding variables makes their interpretation difficult. Based on the literature presented, it is concluded that there are more unknowns than knowns in terms of fluoride's effect on bone, osteoporosis, and fractures. One of the major unknowns in the relationship between fluoride and bone health is dose and duration. Two studies are underway that attempt to describe the dose-response relationship between waterborne fluoride and osteoporosis. These studies will be completed in the near future and their results, while providing new insight into fluoride's effects on bone, will by no means answer all the questions raised on this issue.