Biomedical Engineering Reference
In-Depth Information
cardiovascular, wound healing, and drug delivery systems
[2]
. For bone implants, osseointegration
(integration of bone cells with implant materials) has been a major goal while designing and fabricat-
ing implants; and toward this end, implant surfaces such as these of Ti have been greatly modified to
improve bone cell adhesion and growth, leading to better osseointegration
[3-9]
. It has been shown
previously that cell behaviors such as adhesion and osteoblast differentiation are greatly influenced
by the nanoscale topography of the implant materials
[10-15]
. In the next sections, this chapter will
review methods to create nanotopography on the Ti implants and responses of bone cells toward these
modified surfaces.
8.2
NANOTOPOGRAPHY GENERATED FROM SURFACE
MODIFICATION OF TI IMPLANTS
Titanium in its pure form has been tested and compared with other materials such as stainless steel
and Co-Cr alloys for their biocompatibility
in vivo.
Titanium has commonly been used for dental
implants over several decades. Commercially used titanium are pure Ti (ASTM F67) and Ti-6Al-4V
(ASTM F136)
[14]
. Both pure Ti and its alloys exhibit superior mechanical properties, chemical sta-
bility, and
in vivo
biocompatibility
[16-25]
. Pure Ti is generally used when corrosion resistance is
of greater importance than mechanical strength, whereas Ti-6Al-4V, an alpha-beta alloy, is used
when the mechanical strength is required (
Table 8.1
). However, a major concern when Ti-6Al-4V
Table 8.1
Properties and Bone Tissue Engineering Applications of Different Ti Alloys
[28-33]
Alloys
Elastic Modulus
(GPa)
Ultimate Tensile
Strength (MPa)
Elongation (%)
Applications
Pure Ti
100-110
240-550
15-24
Dental implants,
maxillofacial
and craniofacial
implants, screws for
spinal surgery.
Ti-6Al-4V
110
930
10-15
Total joint
replacement,
primarily for hips
and knees
Ti-6Al-7Nb
105
860
10
Femoral hip stems,
fracture fixation
plates, spinal
components,
fasteners, nails,
rods, screw and
wire.
Ti-13Nb-13Zr
79-84
973-1037
10-16
Orthopedic
implants
Ti, titanium; Al, aluminum; V, vanadium; Nb, niobium; Zr, Zircon.
