Biomedical Engineering Reference
In-Depth Information
matrix and its ability to promote mineral deposition and provide
binding sites for osteogenic proteins [115, 135]. Although collagen
itself is an inadequate bone graft, when combined with ceramics and
growth factors, it becomes a powerful inducer of bone regeneration
[137].
Scaffolds comprised of synthetic polymers offer many advantages
over natural polymers including reproducibility, unlimited supply,
relative lack of immunologic concerns, and tailorable properties
such as degradation rates and mechanical strength [8, 63]. Synthetic
polymers used for bone regeneration include poly(lactic acid)
(PLA), poly(glycolic acid) (PGA), poly(lactic-coglycolic) acid (PLGA),
polypropylene fumarate (PPF), and the polyhydroxyalkanoates
(PHAs) [73]. Combining polymers with ceramics creates bioactive
scaffolds that enhance tissue formation with greater initial strength
[40].
Recently, titanium-hydroxyapatite [94] and Ni-free austenitic
stainless steel/hydroxyapatite [128] nanocomposite biomaterials
were synthesized. These composites could be medically beneicial
in applications such as better biomedical implants with improved
mechanical properties, corrosion resistance, and biocompatibility.
3
.
2 Metallic Biomaterials
Metallic materials are used in biomedical devices for various parts
of the human body (Table 3.4, Fig. 3.2). Metals and its alloys such
as stainless steel, Co-Cr-Mo alloy, commercially pure titanium, and
titanium alloys are widely used as biomedical materials and are
important in medicine and they cannot be replaced with ceramics
or polymers at present mainly because of their high strength and
toughness (Table 3.5).
Ta b l e 3
.
4
Biometallic devices and metallic biomaterials used for them
Biometallic devices
Metallic biomaterials
Artiicial join
Ti-6Al-4V alloy, Co-Cr alloy, 316 stainless steel
Bone plate
Ti-6Al-4V alloy, 316 stainless steel, Ti-6Al-4V alloy
Clip
Ti-6Al-4V alloy, Co-Cr alloy
Crown, bridge
Au-Cu-Ag alloy, Au-Cu-Ag-Pt-Pd alloy, Ti, Ti-6Al-4V
alloy
Dental implant
Ti, Ti-6Al-4V alloy, Ti-6Al-7Nb alloy
Pacemaker
electrode: Pt-Ir alloy, Ti; case: Ti, Ti-6Al-4V alloy
Stent
316 stainless steel, Ni-Ti alloy
