Biomedical Engineering Reference
In-Depth Information
of osseointegration occurred during vital microscopy studies in
rabbits. He and his team found that titanium oculars placed into the
femurs of rabbits could not be removed from the bone after a period
of healing. The irst practical application of osseointegration was
the implantation of new titanium roots in an edentulous patient in
1965. Brånemark implant methods and materials are one of the most
signiicant scientiic breakthroughs in dentistry since the late 1970s.
Table 3.1 gives examples of material properties and their rel-
evance to biomaterials [5, 15, 16]. In general, the physical properties
play an important role only in the case of special functional
applications such as heart pacemaker electrodes. Good chemical
and biological properties are a prerequisite for application as a
biomaterial as mentioned above. The most important mechanical
properties for highly loaded implants such as hip endoprostheses are
fatigue strength and Young's modulus, which leads to the deinition
of the biofunctionality BF as the ratio of the fatigue strength
σ
f
to
Young's modulus
E
[5]:
F=
σ
f
/
E
(3.1)
Biomedical materials can be divided roughly into three main
types governed by the tissue response: (i) inert (more strictly, nearly
inert) materials illicit no or minimal tissue response, (ii) active materials
encourage bonding to surrounding tissue with, (iii) degradable, or
resorbable materials are incorporated into the surrounding tissue, or
may even dissolve completely over a period of time. Metals are typically
inert, ceramics may be inert, active or resorbable and polymers
may be inert or resorbable. Table 3.2 provided some examples of
biomaterials. A comparison of the biofunctionality of various alloys
shows the exceptional properties of titanium and titanium alloys due
to their low Young's modulus (Fig. 3.1).
Figure 3
.
1
Biofunctionality of metallic biomaterials [5].
