Biomedical Engineering Reference
In-Depth Information
One must stress that in the past, many implantations failed
due to various infections, which tended to be exacerbated in the
presence of implants, since they provided a region inaccessible
to the body's immunologically competent cells. Thus, the use of
implantable biomaterials did not become practical until the advent
of an aseptic surgical technique developed by a British surgeon Sir
Joseph Lister (1827-1912) in the 1860s. Furthermore, there was a
lack of knowledge about a toxicity of the selected materials. The exact
chemical composition of the normal calcified tissues of mammals
has been known since, at least, the 1870s, which might be concluded
from both Table 8.1 [24] and the following citations: “The bones
and teeth of animals contain large amounts of calcium phosphate,
together with some carbonate and fluoride.” [43, p. 188] and
“Calcium phosphate is also the chief inorganic constituent of bones,
forming about 80 per cent of burnt bones; the other constituents
being magnesium phosphate, calcium carbonate, and calcium
fluoride.” [43, p. 205]. Those data were updated in 1894 [170].
However, the apatitic structure of the calcium orthophosphates of
bones and teeth has been established by X-ray diffraction in 1926
[171] and confirmed in 1932 [172] and 1933 [173]. Since that time,
bone mineral has been frequently identified as HA. In this frame,
application of calcium orthophosphates as artificial grafts appears
to be logical due to their similarity with the mineral phases of bones
and teeth.
Table 8.1
The chemical composition of two bone samples taken from a
publication of 1871 [24].
Commercial
bone-ash
Pure ox bone-
ash
Moisture and volatile matter
6.70
1.86
Siliceous matter
9.69
0.51
Oxide of iron
0.58
0.17
Lime
43.37
52.46
Magnesia
1.14
1.02
Phosphoric acid
33.68
39.55
Carbonic acid, alkalies, and other
substances undetermined
4.84
4.43
Total
100.00
100.00
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