2010 RWISO Journal - Roth Williams International Society of ...

The distance between the preauricular skin and the flag
table is usually greater in the Axiograph III than it is in the
Axi-Path. Taking this into account, the distance between the
skin and the flag table was set at 8 mm in the Axiograph III.
When the flag table is 8 mm away from the skin, the measurement
error will be 0.36 mm. This is 0.13 mm larger than
the 0.23 mm measurement error with the Axi-Path, which
has the flag table 5 mm away from the skin (Figure 53).
Figure 53 If the distance from the stylus to the skin is 8 mm,
the amount of error will be calculated as follows:
5.68 : 125 = X : 8 mm (X = 45.4 ÷ 125 = 0.36 mm)
If we were to transfer the face-bow of the Axiograph III
system in the same way as we transfer the face-bow of the
Axi-Path system, we would have to shorten the distance between
the skin and the flag table to reduce the measurement
error. However, in the Axiograph III system we use hinge
marks on the graph, rather than hinge marks on the skin, for
precision mounting.
Now let us further suppose that the stylus is placed 50
mm, rather than 8 mm, away from the skin (Figure 54).
Figure 54 Supposition: The stylus is 50 mm away from the skin.
Although this situation is one that we may not encoun-
ter in practice, it is useful as an example to explain an extreme
case (Figure 55).
Figure 55 Magnified view.
It is obvious that the measurement error becomes larger
when the distance from the stylus to the skin is 50 mm (Figure
56). In fact, the measurement error will be 2.3 mm (Figure 57).
Figure 56 The measurement error becomes larger
when the distance from the stylus to the skin
changes from 8 mm to 50 mm.
Figure 57 If the distance from the stylus to the skin
is 50 mm, the amount of error will be calculated as follows:
5.6 8: 125 = X : 50 mm (X = 284 ÷ 125 = 2.3 mm)
RWISO Journal | September 2010
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