Abstract
Microradiographic study of osteofluorosis in growing rabbits reveals that mineralization is intermittently delayed in teeth, endochondral cartilage and bone. In teeth, the changes take the form of alternating hypo- and ‘hyper’-mineralized zones in dentine and enamel matrix; in cartilage, as alternating zones of hypomineralization and calcification in hypertrophic cartilage, with considerable variation in the width of the hypomineralized zone; and in bone, as areas of decreased mineralization within osteones, trabeculae and the margins of osteocytic lacunae, as well as an increased extent of heavily mineralized cement lines and osteone margins. Increased bone mass is due to the accumulation of large amounts of fluorotic bone resulting from delayed resorption of the matrix of cartilage and from excessive growth of endosteal and/or periosteal bone. Delayed resorption of the metaphysis is associated with failure of calcification and mechanical compression of uncalcified cartilaginous matrix. The latter subsequently becomes mineralized to form wide striae in the metaphysis. It is postulated that these effects impede normal resorptive processes along columns of cartilage and may be responsible for weakening and frequent separation of the epiphysis from the shaft.