Biomedical Engineering Reference
In-Depth Information
a
b
5000
120
100
4000
80
3000
60
2000
Sample 1
Sample 2
Sample 1
Sample 2
40
1000
20
-4
-2
0
2
4
-4
-2
0
2
4
Y axis (
µ
m)
Y axis (
µ
m)
Fig. 5.7
Distribution of the nanoindentation hardness and elastic modulus along the enamel rod's
y
-axis over its occlusal cross section: (
a
) hardness and (
b
) Young's modulus
a
b
5000
120
100
4000
80
3000
60
2000
Sample 1
Sample 2
Sample 1
Sample 2
40
1000
20
-2
0
2
-2
0
2
X axis (
µ
m)
X axis (
µ
m)
Fig. 5.8
Distribution of the nanoindentation hardness and elastic modulus along the enamel rod's
x
-axis over its occlusal cross section: (
a
) hardness and (
b
) Young's modulus
modulus shows a similar trend to the hardness. The largest elastic modulus in the
head area is about 85 GPa, and the lowest elastic modulus in the tail area is about
70 GPa.
Figure
5.8
shows the distribution of the nanoindentation hardness and elastic
modulus along the
x
-axis of the enamel rod over its occlusal cross section. The hard-
ness and elastic modulus in the center were a little higher than those measured at the
edge of an enamel rod.
Table
5.1
gives the average values of the mechanical properties obtained from
these indentations. Here, the head area refers to the area between
y
= 0~2 μm and the
tail area refers to the area between
y
= −3 ~ −1 μm. The hardness and elastic modulus
tended to be lower in the tail area of both the rods and the interrod enamel in com-
parison with those in the head area of the rods. Such results were consistent with
those of Habelitz et al. [
4
].
To understand the possible reasons for the heterogeneous mechanical properties
of a single enamel rod, the EDX detection was conducted on the various positions
of an enamel rod. As shown in Fig.
5.9
, the contents of the C, O, P, and Ca elements
