Biomedical Engineering Reference
In-Depth Information
been proposed that the low level of water ordering at the interface is
correlated with the low solubility of DCPD in water [144]. recently,
data on DCPD solubility have been updated [145]. The optical
properties of DCPD are well described in ref. [146], while many
additional data on DCPD, as well as a good picture of DCPD atomic
structure are available in literature [147].
DCPD is of biological importance because it is often found in
pathological calci fi cations (dental calculi, crystalluria, chondro calci-
nosis, and urinary stones) and some carious lesions [27, 83-85]. It
has been proposed as an intermediate in both bone mineralization
and dissolution of enamel in acids (dental erosion) [27, 83, 84]. In
medicine, DCPD is used in calcium orthophosphate cements [131,
148-151] and as an intermediate for tooth remineralization. DCPD
is added to toothpaste both for caries protection (in this case, it is
coupled with F-containing compounds such as NaF and/or Na
F)
and as a gentle polishing agent [152-156]. Other applications
include a flame retardant [157], a slow release fertilizer, using in
glass production, as well as calcium supplement in food, feed and
cereals [134]. The importance of DCPD as a constituent of infant's
food was discovered as early as in 1917 [158]. In food industry, it
serves as a texturizer, bakery improver and water retention additive.
In diary industry, DCPD is used as a mineral supplement. If added
to food products, DCPD should be marked as E341 according to
the European classification of food additives. In addition, plate-like
crystals of DCPD might be used as a non-toxic, anticorrosive, and
passivating pigment for some ground coat paints.
PO
2
3
1.3.4
DCPA or DCP
; the chemically correct
name is calcium hydrogen orthophosphate anhydrate; the mineral
monetite [159]) is the anhydrous form of DCPD. It is less soluble
than DCPD due to the absence of water inclusions. like DCPD, DCPA
can be crystallized from aqueous solutions but at temperatures
~100°C. Furthermore, it might be prepared at room temperature in
gels [139], ethanol [160], as well as in oil-in-water and water-in-oil
systems [161]. DCPA is physically stable and resisted hydration even
when dispersed in water for over 7 months in the temperature range
of 4-50°C [162]. A calcium-deficient DCPA was prepared recently.
It might be sintered at ~300°C [163]. unlike DCPD, DCPA occurs in
Dicalcium phosphate anhydrous (CaHPO
4
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