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286 Materials and Nanotechnology | Progress Report
tional resistive heating, microwave energy ties of the implants, material scientists have
and two-step sintering. Promising results have tried several surface modifications including
been observed with the addition of 10-20wt% mechanical treatment, thermal spraying, sol–
of alumina and 10-30wt% of titania. gel coatings, chemical and electrochemical
treatment, ion implantation, and so on.
Biomedical metals
When a biomaterial has the first contact with
the body, its surface adsorbs proteins from
blood and interstitial fluids. The inflammato-
ry response depends on this formed layer of
proteins, which will determine the activation
of coagulation cascade, complement system,
platelets and immune cells. Depending on
the cellular and immune responses at the im-
plantation site of biomaterials, rejection or
degradation of the implant may take place.
The key to the improved implant performance
is to develop materials capable of avoiding
detrimental immune responses.
Figure 9: FEG-SEM image of Y-TZP-20 wt% Al O composite.
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Titanium is the main metal studied for implant
application due to its biocompatibility and de-
sirable mechanical properties. To improve the
biological interaction of the implant with bone,
different processes using surface modification
have been performed; with the same goal to
improved biological interaction, a new concept
of structure modification is being applied. In
that way, metallic porous structure can provide
good mechanical properties and enhanced
biological interactions, by the phenomenon of
tissue invasion also referred as bone-ingrowth.
Figure 10: X-ray diffraction patterns of Y-TZP/TiO samples after
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coating. The porous implants must have interconnect-
ed porosity that give the support required for
The topography of metallic implants is one vascular continuous nourishing allowing min-
of the factors that influence the bone healing eralization of bone tissue. Thus, pore channels
and the osseointegration process. Machined must allow the infiltration of cells responsible
implants have been used for many years, but for formation of the tissue matrix within the
some studies have shown that the increase material, in order to meet the requirements for
in surface roughness tends to enhance, not a lasting healing rehabilitation.
only the interface between the bone and the
implant, but also the bond strength at this Production methods of porous metallic mate-
interface Therefore, in order to improve the rials for implants are mainly based on powder
biological, chemical, and mechanical proper- metallurgy (PM), because it allows the manu-
Instituto de Pesquisas Energéticas e Nucleares
