MATERIALS FOR ORTHOPEDIC APPLICATIONS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 83

produce a strong attachment to epithelial and connective tissues. The cementless
fi xation of hip prosthesis components and the retention of dentures by oral im-
plants are two exciting examples of the clinical application of titanium. Yoshiki
Oshida describes the science and technology of integrated Ti implant in a sepa-
rate chapter of this topic.
Vannoort 106 assessed the different possible application of Ti in human body.
The two most popular applications of Ti and its alloy include dental inserts and
THR application. He showed that Ti had good biocompatibility property in both
the applications.
Gordin et al. 107 developed a new Ti-based alloy that combined Ti with the
non-toxic elements, like Ta and Mo. This newly developed titanium alloys exhib-
ited spontaneous passivity and high corrosion resistance in Ringer's solution
(SBF).
In another study 108 , novel TiZr alloy foams with relative densities of approxi-
mately 30%

th were fabricated by a powder metallurgical process. The TiZr alloy
foams displayed an interconnected porous structure resembling bone and the
pore size ranged from 200 - to - 500

ρ

m. The compressive plateau stress and the E-
modulus of the TiZr foam were 78.4 MPa and 15.3 GPa, respectively. Both the
porous structure and the mechanical properties of the TiZr foam were very close
to those of natural bone.
Hollander et al. 109 tested DLF-produced (Direct Laser Forming) Ti6Al4V
material for hard tissue applications. The cells spread and proliferated on
DLF-processed Ti6Al4V over a culture time of 14 days. On porous specimens,
osteoblasts grew along the rims of the pores and formed circle- shaped
structures.
Matter and Burch 110 illustrated their experience with titanium implants, espe-
cially with the limited contact dynamic compression plate system. They confi rmed
the outstanding biocompatibility of Ti metal.
Johansson and co - workers 111 demonstrated that commercially pure (cp) Ti
and cp Zirconium can be well accepted for tibia implants. After implantation in
an animal or human body, the interface between metallic implant and bone plays
an important role towards the curing of patients. Good chemical bonding or me-
chanical interlocking is desired for long term implantation.
Sennerby et al. 112 analyzed the interface zone between cortical bone and
threaded non-alloyed titanium implant, which was inserted in the rabbit tibia for
12 months. Their observations suggested that mineralized bone reached close to
the surface of titanium implants inserted in the rabbit tibia for 12 months; how-
ever, a direct contact was not established.
Muster et al. 113 observed the growth process of two different metals, that is Ti
and gold. They showed that in the case of a bone-titanium interface, an interme-
diate compound is built which defi nitely contributes to its stability. In gold-bone
interfaces, such a compound has not been observed, and growth seems less regu-
lar. In the case of the bone-titanium interfaces, a partial substitution of Ca with Ti
occurs in the hydroxyapatite. This intermediate compound may be considered as
a factor of stability and tolerance.

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