Biomedical Engineering Reference
In-Depth Information
Tabl e 9. 7
Composition in %(w/w) of a bioactive glass and a glass ceramic (data collected
from [
303
-
305
]; GC D glass-ceramic)
45S5
KG Cera
MB GC
A-W
BAG
G-C
G-C
G-C
SiO
2
45
46:2
19-52
34:2
P
2
O
5
6
4-24
16:3
CaO
24:5
20:2
9-3
44:9
CaF
2
0:5
Ca(PO
3
)
2
25:5
MgO
2:9
5-15
4:6
Na
2
O
24:5
4:8
3-5
K
2
O
0:4
3-5
Al
2
O
3
12-33
Fig. 9.15
Dissolution of
bioactive glass grains
(Biogran
R
) after two months
of implantation in a beagle
dog's jaw. Original
magnification X100,
Stevenel's blue and Von
Giesen Picro-fuchsin stain.
By courtesy of Prof. E.
Schepers (UZ-KULeuven,
Department of Dentistry)
chain in the middle ear and occasionally coatings (see Sect.
9.5
). Another poten-
tial opening to application is the integration by ion-exchange of Ag
C
. The authors
report antibacterial activity at nontoxic levels and improvement of the bioactivity of
the starting glass [
302
].
Before concluding the subject, still a pretty fact about the interaction between
medium-sized BAG grains (300-350
m) and bone. Figure
9.15
shows how, after
2 months of implantation in the lower jaw of beagle dogs, the particles are partly
dissolved - big surprise - not starting at the surface but excavated!
One of those wonderful but capricious ways along which nature is acting! Six
months later, bone formation is noticed inside the cavities [
306
,
307
]. An example
of a nontoxic and soluble product, which is gradually replaced by osseous tissue.
9.4.2
Glass-Ceramics
Glass-ceramics contain within the vitreous mass microcrystalline particles and
differ as such from glass, which is structurally a homogeneous material. These
