H. Kawamura et al., Stimulatory effect of zinc-releasing calcium phosphate implant on bone formation in rabbit femora, J BIOMED MR, 50(2), 2000, pp. 184-190
Although hydroxyapatite (HAP) and tricalcium phosphate (TCP) are currently
used as bone graft substitutes or coatings on metallic prostheses because o
f their excellent biocompatibility and osteoconductivity, they do not stimu
late bone formation or inhibit bone resorption. Zinc, an essential trace el
ement in many animals, has a direct specific proliferative effect on osteob
lastic cells and has a potent and selective inhibitory effect on osteoclast
ic bone resorption in vitro. Therefore, zinc-containing p-tricalcium phosph
ate (ZnTCP) ceramics and composite ceramics of ZnTCP and HAP (ZnTCP/HAP) we
re implanted in the femora of New Zealand White rabbits for il weeks to pro
mote bone formation. The implants were sintered ceramics with zinc contents
of 0 (control), 0.063, 0.316 and 0.633 wt %. Histological and histomorphom
etrical investigation of the undecalcified sections revealed an increase by
51% (p = .0509) in the area of newly formed bone around the ZnTCP/HAP impl
ants of 0.316 Zn wt % compared with the control. Plasma zinc concentration
was unchanged. An increased bone resorption on the endosteal surface was ob
served when ZnTCP and ZnTCP/HAP of 0.633 Zn wt % were implanted. To promote
bone formation, the optimum zinc content of the calcium phosphate ceramics
was therefore 0.316 wt %. (C) 2000 John Wiley & Sons, Inc.