FLUORIDE AND THE SKELETON

Fluoride has the potential to increase skeletal mass to a greater exte nt than any other pharmacologic agent, yet it has proven difficult to translate this into therapeutic benefit for patients with low bone mas s in diseases such as osteoporosis. This apparent paradox can be expla ined in part by toxic actions of the ion on skeletal mineralization, i mpairment of the normal processes of bone resorption, and flouride-ind uced decreases in strength per unit of bone (mass or volume). In part, the paradox can be explained by the late stage of osteoporosis in mos t patients enrolled in controlled clinical trials of flouride, with al terations in skeletal microarchitecture beyond which restoration of me chanical integrity is not likely. Exposure of calcified tissues to env ironmental fluoride (water supply, dentifrices) also offers paradoxes. The anticaries effects are well documented as are the deleterious ske letal effects of endemic fluorosis when environmental exposure is too high. More controversial is the effect of seemingly nontoxic levels of exposure on the prevalence of osteoporotic fractures of the hip. This review attempts to provide a balanced overview of the conflicting lit erature concerning therapeutic and environmental effects of fluoride o n the skeleton.