Biomedical Engineering Reference
In-Depth Information
While only one type (i.e., CHA or CFA) of calcium phosphate is present
in normal calcifi cations (enamel, dentin, cementum, bone), different types of
calcium phosphates co-exist in some pathologic calcifi cations or diseased states
as shown in Table 2.1 [57,59,64]. For example, in dental calculus, simultaneous
presence of DCPD, OCP, Mg-
β
TCP and CHA have been observed [59,64,112].
2.6 CALCIUM PHOSPHATE-BASED BIOMATERIALS
The fi rst successful application of a calcium phosphate reagent for bone repair
was reported in 1920 [1]. It was not until more than 50 years later that calcium
phosphate materials were developed for medical and dental applications [2,18,46].
Commercial calcium phosphate ceramics used currently as biomaterials for
bone repair, augmentation, substitution include: HA, calcium-defi cient apatite
(CDA),
- TCP
ratios), listed in Table 2.6 [2,12,15,18,46,62,64,70,75,84]. Commercial HA is either
of biologic (e.g., coral, bovine bone, marine algae) or synthetic origin [16,35,
62,64,120] .
HA ceramic (used as biomaterials) and biologic apatite (e.g., bone mineral)
differ in the following properties (Figure 2.11) [6,64]: (a) crystal size, (b) composi-
tion, and (c) solubility. HA and biologic apatite also differs in their manner of
dissolution: biologic apatite shows preferential dissolution of the core, while HA
has non - preferential dissolution [14] .
HA bioceramics (commercial) are usually prepared by preparation at high
pH (e.g., pH 10) then sintering between 950 °C and 1100 °C [18,46,64].
β
-TCP, BCP (intimate mixture of HA and
β
- TCP of varying HA/
β
TABLE 2.6. Clinical Applications of Commercial Calcium Phosphate ( C a P ) Biomaterials
CaP Biomaterials
Applications
Ref
HA (ceramic, bovine - bone
derived, coral derived)
bone graft substitute, sinus
grafting, periodontal defects,
bone augmentation, orthopedic,
scaffold, drug delivery
[2,15,16, 18,20,23,
35,46,54,62,64,70,
75,120]
HA (ceramic)
abrasive, source for plasma -
sprayed coating on orthopedic
and dental implants
[18,30,37,46,55]
bone graft substitute, fractures,
spinal fusion, dental, orthopedic
[62,64,75]
β
- TCP
BCP (HA +
β
- TCP)
spine fusion, revision surgery,
fractures, bone graft substitute,
trauma surgery, opthalmic
implant, scaffold
[12,75 96,119]
HA/polyethylene, BCP/silicon
middle ear prostheses
[8,75]
Calcium phosphate cement,
CPC
bone fi ller bone tumor, bone cyst,
periodontal defects, fracture
[101]
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