Biomedical Engineering Reference
In-Depth Information
Furthermore, various bioorganic impurities in the local environment
undoubtedly influence the crystallization process, resulting in a great
variety of pathological deposits. Thus, it is a highly complex problem.
In some cases, the chemical composition of an unwanted inorganic
phase might depend on the age of the pathological calcification and
its location. For example, DCPD is more frequently found in young
(3 months or younger) calculus, biological apatite is present in all
ages of calculus, while β-(Ca,mg)
occurs more frequently in
sub-gingival calculus. In mature calculus, the relative abundance of
OCP, β-(Ca,mg)
(PO
)
3
4
2
and biological apatite also differ between the
inner and outer layers [84]. It is interesting to note that the mineral
phases of animal calculus (e.g., from dog) was found to consist of
calcium carbonate and biological apatite, while human calculi do not
contain calcium carbonate [84, 837].
(PO
)
3
4
2
Table 1.4
Occurrence of calcium phosphates in biological systems
(human) [84].
Calcium phosphate Occurrence
Biological apatite
Enamel, dentine, bone, dental calculi, stones, urinary
stones, soft-tissue deposits
OCP
Dental calculi and urinary stones
DCPD
Dental calculi, crystalluria, chrondrocalcinosis, in
some carious lesions
β
-(Ca,mg)
(PO
)
Dental calculi, salivary stones, arthritic cartilage, soft-
tissue deposits
3
4
2
Ca
P
O
·2H
O
Pseudo-gout deposits in synovium fluids
2
2
7
2
ACP
Heart calcifications in uremic patients, kidney stones
The nucleation process is the main step in both normal and
pathological calcifications.
experiments conducted by Grases
and Llobera [838] to simulate the formation of sedimentary urinary
stones, demonstrated that in the absence of organic matter no
calcium orthophosphates crystallized in cavities with scarce liquid
renovation, but regular CDHA layers appeared on the wall around
the cavity. Visible deposits of calcified organic materials (mixtures
of organic matter and spherulites of CDHA) were formed when a
In vitro
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