Porous calcium phosphate ceramics consisting of hydroxyapatite (HA) and tri
calcium phosphate (TCP) with different HA to TCP ratio were implanted intra
muscularly in rabbits for six months in order to carry out a comparative st
udy on osteogenic activity of the ceramics. Bone formation was detected onl
y in HT73 (HA to TCP ratio; 7-3) specimens. Other implants, HT28 (2-8) and
HT010 (0-10), could not induce bone. After a six-month period of implantati
on, HT28 and HT010 implants showed obvious degradation of the implants chan
ging their shape and size macro and microscopically. Microscopically, they
showed aggregates of fine particles and appearance of multinucleated cells.
However, HT73 implants was less degraded and could maintain their original
structure macro and microscopically. This study showed that HT73 ceramics
can induce bone in rabbit muscle tissue and it is considered that maintenan
ce of porous structure, that is, degradation rate of the materials may be o
ne of the affecting factors in ceramic-induced osteogenesis. (C) 2001 Elsev
ier Science Ltd. All rights reserved.