BIOMATERIALS
UDC 620.22-419.8
APATITE-DIOPSIDE BIOGLASS CERAMIC COMPOSITES
V. M. Pogrebenkov,
1
V. V. Shumkova,
1
and V. V. Pogrebenkova
1
Translated from Steklo i Keramika, No. 3, pp. 22 – 24, March, 2004.
The results of research into glass-ceramic materials for medical purposes are described. The effect of the li
-
quid phase composition in the sintering of composites on the conversion of hydroxyapatite into tricalcium
phosphate is determined. The possibility of controlling the structural-mechanical properties, bioactivity, and
time of implant resorption by varying the ratio between hydroxyapatite and diopside glass ceramic in the com
-
position of biological materials is demonstrated.
One of the targets of the contemporary science of materi-
als is the development of materials for different functional
purposes for medicine. In many cases a condition for suc-
cessful application of ceramics and glass ceramics in den-
tistry and implant surgery is its biological activity, which is
achieved by including hydroxyapatite Ca
5
(PO
4
)
3
OH, which
is a mineral analog of human bone, in the composition of
bioceramics. This calcium-phosphate compound is a bioac-
tive basis for most biomaterials.
Bioglass ceramics is promising for production of bone
implants and defect fillers. The use of the bioactive compo
-
nent (hydroxyapatite) and crystallized glass in a composite
makes it possible to combine sufficient porosity with high
mechanical strength of material. The mechanical properties
of artificial prosthesis should be adequate to actual loads on
human bones or teeth [1]. The presence of porosity is essen
-
tial for assimilation of bioceramics and its integration into
bone tissue.
The synthesis of hydroxyapatite was conducted by the
solid-phase-phase method according to the reaction
10CaCO
3
+ 6(NH
4
)
2
HPO
4
®
Ca
10
(PO
4
)
6
(OH)
2
+ 10CO
2
+ 12NH
3
+8H
2
O.
The study of the reaction products by the complex me
-
thods of thermal, x-ray phase, and IR-spectroscopic analysis
demonstrated that hydroxyapatite with a ratio of Ca : P equal
to 1.66(6) produced by firing at 1100°C with an exposure du
-
ration at the final temperature for 2 h and having the maxi
-
mum phase homogeneity has the optimum properties for its
further use in producing composite materials [2].
It is promising to use glass of diopside composition,
which crystallizes under heat treatment in the course of
sintering of a composite material, as a matrix for hydroxy-
apatite, since the diopside matrix is inert in relation to the or-
ganism, which at a certain stage is necessary for supporting
soft tissues during biodegrading of the implant and regenera-
tion of the bone. The bioactivity of the composite in this case
will depend on its hydroxyapatite content.
The material used for production of diopside glasses was
natural diopside mineral from the Slyudyanskoe deposit
(Irkutsk Region) that has a high content of the principal min
-
eral and a low quantity of impurities, which makes it suitable
for biomedical purposes. The use of high-purity natural ma
-
terial lowers the production cost of implants.
In glass melting, natural diopside is preferable to pure
oxides. The reactions of diopside formation in a batch based
on pure oxides are rather difficult to implement. The amount
of diopside formed at a temperature of 1300°C comprises
5 – 7%. In this case substantial quantities of SiO
2
, MgO, and
CaO retain their original state up to the temperature of glass
melting, which perceptibly hampers glass melting. The prod
-
ucts of crystallization of glass based on pure oxides in addi
-
tion to diopside include magnesium metasilicate and wolla
-
stonite. Due to the specific pyroxene structure of natural di
-
opside, its structural groups persist in the melt and in glass in
the production of glass ceramics, which ensures the high
crystallization capacity of glass and its monomineral crystal
-
lization [1, 3].
The glass composition selected for research was the
CaO – MgO – Al
2
O
3
– SiO
2
system, which after complete
crystallization was to form 75% crystalline phase, i.e., diop
-
side, and 25% vitreous phase in the system CaO – Al
2
O
3
–
Glass and Ceramics Vol.61, Nos.3–4, 2004
87
0361-7610/04/0304-0087 © 2004 Plenum Publishing Corporation
1
Tomsk Polytechnical University, Tomsk, Russia.