Calcium Orthophosphates as Bioceramics - Calcium Orthophosphates: Applications in Nature, Biology and Medicine - page 380

Figure 4.14 A schematic diagram representing the events, which take place

at the interface between bioceramics and the surrounding
biological environment: (1) dissolution of bioceramics; (2)
precipitation from solution onto bioceramics; (3) ion exchange
and structural rearrangement at the bioceramic/tissue
interface; (4) interdiffusion from the surface boundary layer
into the bioceramics; (5) solution-mediated effects on cellular
activity; (6) deposition of either the mineral phase (a) or the
organic phase (b) without integration into the bioceramic
surface; (7) deposition with integration into the bioceramics;
(8) chemotaxis to the bioceramic surface; (9) cell attachment
and proliferation; (10) cell differentiation; (11) extracellular
matrix formation. All phenomena, collectively, lead to the
gradual incorporation of a bioceramic implant into developing
bone tissue. Reprinted from Ref. [58] with permission.

An important study on formation of calcium orthophosphate
precipitates on various types of bioceramic surfaces in both
simulated body fluid (SBF) and rabbit muscle sites was performed
[639]. The bioceramics were sintered porous solids, including
bioglass, glass-ceramics, α-TCP, β-TCP and HA. An ability to induce
calcium orthophosphate precipitation was compared among these
types of bioceramics. The following conclusions were made: (1) OCP
formation ubiquitously occurred on all types of bioceramic surfaces
both , except on β-TCP. (2) Apatite formation did

not occur on every type of bioceramic surface; it was less likely to
occur on the surfaces of HA and α-TCP. (3) Precipitation of calcium
orthophosphates on the bioceramic surfaces was more difficult
in vivo

in vitro and in vivo

. (4) Differences in calcium orthophosphate
precipitation among the bioceramic surfaces were less noticeable

than in vitro

in

vitro . (5) β-TCP bioceramics showed a poor ability

of calcium orthophosphate precipitation both

than that in vivo

in vitro and in vivo