Biomedical Engineering Reference
In-Depth Information
A.
B.
Figure 8.8.
Selected region of the interfacial tissue sur-
rounding a dental implant showing stretched collagen fibers,
similar to those observed during distraction osteogenesis. The
section along the long axis of the dental implant was stained
with Stevenel's Blue and van Gieson's Picro-Fuchsin and was
observed under 30
×
magnification. Arrow shows bone; star
shows the implant.
(
700
and
1000
µε
) reported by McLeod and
Rubin [
],
respectively. Nonetheless, the effect on bone
formation was clear. Qin et al. [
84
] and by Rubin and Lanyon [
100
96
] reported
C.
that a threshold near
can induce antire-
sorptive bone formation, and our fi ndings
agree with these conclusions. It is possible that
progenitor cells within alveolar or healing bone
are more susceptible to low strain thresholds,
so that even a small strain can induce substan-
tial bone regeneration.
70
µε
8.5 Summary
Mineralized biological tissues are essentially
composite materials with dynamic structures
that can change because of increases or
decreases in mineralization via apatite nucle-
ation and growth or dissolution processes. This
balance gives rise to structures not seen in
engineering composites. Biological and biome-
chanical factors are two of the most important
factors infl uencing the dynamics of regener-
ated bone. Healing can regenerate bone through
biological cascades by altering gene expression
in bone cells. This natural process involves
soluble factors delivered from blood or released
at the local injured site. Modifi cation of healing
0
0.28
0.63
1.19
2.0 g/cm
3
Figure 8.7.
(A) Microcomputer tomographic image of tissue
architecture produced from one of our animal studies. This was
considered to represent an equilibrium stage (attractor state).
(B) The bony density and architecture predicted by tensile
stress criteria appeared to match the patterns shown in (A). (C)
The bony pattern predicted by Von Mises criteria did not match
that of experimental data. This result indicated that cells sur-
rounding an osseointegrated dental implant are susceptible to
tensile force stimulation, which differs from implants placed in
long bone.
