Biomedical Engineering Reference
In-Depth Information
0.1
mm
Figure 4.7.
Pure
β
-TCP implanted in a dog mandibular defect showing no bone contact with
the granules and extensive resorption at the surface of the grain (arrow).
4.4 BIOCERAMICS: NEW DEVELOPMENTS
4.4.1 Microstructure Improvement
At present, granules and particles are used increasingly in mouldable, injectable
or resorbable composites. However, the biological behaviour of the particles can
be infl uenced not only by chemical composition and crystalinity, but by several
other parameters such as granulometry and microporosity. The infl uence of
microporosity on new-bone formation, though apparently one of the more
complicated variables, has rarely been studied, unlike macroporosity. A recent
study by O. Malard et al. [51] is reported. Two different porosities of biphasic cal-
cium phosphate granules were prepared (20% and 40% porosity) and evaluated
in rat critical size defects. This study sought to specify the role of microporosity in
an
in
vivo
experiment, as well as examine the amount and kinetics of newly-
formed bone ingrowth, and the biodegradation of BCP ceramic. LP (20%) and
HP (40%) microporous granules were prepared from calcium-defi cient apatite
(CDA) sintered at 1050 °C which resulted in a biphasic calcium phosphate BCP
of 60% HA and 40%
β
-TCP. XRD showed BCP content without trace of carbon-
ate, with an HA/
-TCP ratio of 60/40. No difference was observed between the
HP and LP granules. SEM image analysis showed that porosity was 17.6%
β
±
3.6
for LP granules and 39.7%
0.001). LP granules were
regular rounded granules and HP granules were more irregular in shape, with a
sharper surface.
±
10.3 for HP granules (p
<
Search WWH ::
Custom Search