MINERALIZATION OF CANCELLOUS BONE AFTER ALENDRONATE AND SODIUM-FLUORIDE TREATMENT - A QUANTITATIVE BACKSCATTERED ELECTRON IMAGING STUDY ON MINIPIG RIBS

Fluoride stimulates bone formation, whereas bisphosphonates reduce bon e resorption. In clinical trials, both treatments increase bone densit y, although sodium fluoride (NaF) increases and alendronate (bisphosph onate, ALN) decreases bone turnover, In a comparative study using mini pigs an inverse correlation has been reported between bone turnover an d elastic modulus, Small-angle X-ray scattering (SAXS) measurements of these bones revealed no structural deterioration of the collagen/mine ral composite at the nanometer range for ALN-treated vertebra, whereas a slight increase of the average thickness of the mineral crystals as well as changes of the structure of the collagen/mineral composite we re found in the bones of NaF-treated animals. In this study we used qu antitative backscattered electron imaging (qBSE) to investigate the ca ncellous bones from ribs of minipigs treated with vehicle, NaF, or ALN , This method provides information on the local mineral concentration in the micrometer range, Mineralization spectra were obtained from eac h treatment group, and statistically significant differences between A LN and controls were found for the peak position, the peak height, the peak width, and the average calcium (Ca) concentration of the mineral distribution, The results reveal that the cancellous bone matrix was more uniformly mineralized after ALN treatment. The reduced bone turno ver induced by ALN, documented histomorphometrically could be at the o rigin of this phenomenon, No significant differences were detected bet ween NaF and control, Together with the earlier SAXS data these result s may explain in part the increase in bone density and the improvement of biomechanical properties observed after ALN treatment in animals a nd in osteoporotic patients. (C) 1997 by Elsevier Science Inc.