Biomedical Engineering Reference
In-Depth Information
Table 19.1
Design Criteria for Bone Tissue Engineering Scaffolds
1. Ability to deliver and/or mediate
appropriate cellular interactions
The material should not only be biocompatible, but also foster
attachment, differentiation, and proliferation of osseous and
vascular cells as needed.
2. Osteoconductivity with host bone
An ideal scaffold should not only eliminate the formation of fibrous
tissue encapsulation but also result in a strong bond between the
scaffold and host bone.
3. Biodegradability
The composition of the material, combined with the porous
structure of the scaffold, should result in biodegradation in vivo at
rates appropriate to tissue regeneration.
4. Mechanical properties
The mechanical strength of the scaffold should be sufficient to
provide mechanical stability in load bearing sites before the
synthesis of new extracellular matrix by cells is completed.
5. Porous structure
The scaffold should have an interconnected porous structure with
porosity
m for cell
penetration, tissue ingrowth and vascularization, and nutrient
delivery.
90% and diameters between 300
500
μ
.
6. Fabrication
The material should possess desired fabrication capability, e.g.,
being readily produced into irregular shapes of scaffolds that match
the defects in bone of individual patients.
7. Translational potential
The fabrication of the scaffold should be suitable for
commercialization and approval for use in specified clinical
procedures.
(Adapted from Ref.
[4]
)
development of nanoceramics that fulfill many of the desired qualities for a bone scaffold and have
great clinical potential in bone regenerative procedures in dentistry.
19.2
Nanoceramics and bone repair
Many investigations of nanophase materials to date have illustrated their general characteristics for
bone repair. For example, increased bone forming osteoblast adhesion on nanograined materials in
comparison to conventional (micron-grained) materials has been reported
[6,7]
. Osteoblast prolifer-
ation in vitro and long-term functions were also enhanced on ceramics with grain or fiber sizes less
than 100 nm
[7,8]
. In addition to osteoblast responses, reports of modified behavior of bone resorp-
tive osteoclastic cells have also been documented on nanophase ceramics
[6]
and in vivo studies
have demonstrated increased new bone formation on metals coated with nanohydroxyapatite com-
pared to conventional apatite
[9]
.
The significance of nanotechnology is that it creates materials that mimic the natural nanostruc-
ture of living human tissues. With specific reference to bone, it is important to note that this tissue
is a natural nanostructured composite material composed of intimately connected inorganic (bone
apatite) and organic compounds (mainly collagen but also noncollagenous proteins). Due to the
