Biomedical Engineering Reference
In-Depth Information
Bracket
at 10° slot
FIGURE 13.10
A photograph showing the device used to mount the brackets and orthodontic wires onto the Instron setup
for the simulation of the archwire functioning in the mouth. About 12-cm segments of the orthodontic wires
(coated and uncoated) were attached, on their upper part, to a 10-Newton load cell and the lower end was
connected to a 150 g weight. The wires were then inserted into the slots in the brackets and ligated with an
elastomeric module to all four wings of the brackets with 10
angulation. The 150 g weight was used to
restraighten the wire following its insertion into the bracket similar to the clinical situation
[41]
.
Table 13.1
Summary of the Results of the Tribological Tests of SS Orthodontic Wires (N
6
SD)
Angle/Coating
0
5
10
Noncoated wire
1.32
6
0.12
2.95
6
0.09
4.00
6
0.19 dry
3.35
6
0.21 wet
NiP
1
IF-coated wire
1.10
6
0.06
1.58
6
0.25
1.85
6
0.21 dry
1.57
6
0.23 wet
measurements. Each data point is an average of five different measurements. The results of these
series of experiments are summarized in
Table 13.1
.
The mechanism by which the reduced friction of the coated wire is achieved can be explained
by the models suggested in Refs.
[36]
and
[42]
. At the first stage, when there is no angle between
the slot and wire, the IF NP act as spacers and reduce the number of metal asperities that come into
contact, resulting in a lower coefficient of friction. As the angle grows, the load at the edges of the
