Compressive strength, ash weight, and volume of vertebral trabecular bone in experimental fluorosis in pigs

The aim of the investigation was to measure the effect of fluoride on vertebral trabecular bone compressive strength and to correlate this with fluoride-induced changes in bone density. This correlation would express changes in the quality of bone during fluoride treatment. Pigs were used in the experiment because their trabecular bone structure and remodeling sequences are very similar to the human. Eight animals receiving a supplement of 2 mg F-/kg b.w. per day from age 8-14 months were compared with 8 control animals. Morphologic measurements in the animals receiving fluoride supplement showed a significant increase of 17% in bone density and a smaller, insignificant increase of 3% in ash weight analyses. Meanwhile, the mechanical parameters for the fluorotic animals were unchanged (maximum compressive strength, maximum stiffness, and energy-absorption capacity) or decreased (normalized compressive strength = maximum compressive load corrected for ash density). It is concluded that the increased bone mass during the initial stages of fluoride treatment does not necessarily indicate an improved bone quality. The discrepancy between bone mass and strength could be either a permanent or a temporary phenomenon and requires further investigation.