Quantitative comparison of osteoconduction of porous, dense A-W glass-ceramic and hydroxyapatite granules (effects of granule and pore sizes)

The osteoconductive potentials of dense, small porous and large porous apat ite- and wollastonite-containing glass-ceramic (A-W GC) granules of various sizes implanted in rat tibiae were evaluated quantitatively, by determinin g their affinity indices. The average affinity indices of all types of A-W GC were high. The dense A-W GC granules had the highest values (97.0 +/- 5. 5%), followed by the large porous (87.1 +/- 8.4%) and then the small porous granules (79.0 +/- 8.4%). There were no significant differences among the osteoconductive potentials of the different sizes of each form of A-W GC gr anule. The osteoconductive potentials of four types of commercially availab le porous hydroxyapatite (HA) granules were compared with those of the smal l porous A-W GC granules, using the affinity index and the proportion of ne wly formed bone relative to that of the granules in the bone defect. The va lues of the former parameter for three types of HA and those of the latter for four were significantly inferior to those of A-W GC. The difference bet ween the osteoconductive potentials of A-W GC and HA was considered to be r elated to the rate of surface apatite layer formation. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.