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Positioning the Tube Head | Up
Dental Technican, Volume 2 - Dentist training manual for military dentists | Next
Film and cylinder placement: mandibular molar area |
Figure 1-20.—Film and cylinder placement: mandibular bicuspid area.
using anatomical landmarks on the patient's face. Tell
your patient to maintain the position of the placement
of the dental film and not to move while you expose the
radiograph.
VERTICAL ANGULATION.—This
is
the
up-and-down positioning of the tube head. A 0°
vertical angulation indicates that the tube head is
positioned with the cylinder parallel with the floor (fig.
1-26). Angling the tube head so the cylinder points
upward from 0° will give you a minus (–) degree of
vertical angulation. Angling the tube head so the
cylinder points downward from 0° will give you a plus
(+) degree of vertical angulation.
Different areas of the mouth require different
degrees of vertical angulation. The correct vertical
angulation can usually be obtained by using the angles
shown on the chart in figure 1-26. Notice the tube head
is angled downward for maxillary radiographs, and
usually angled upward for mandibular radiographs.
The tube head may be horizontal (0°) when X-raying
mandibular molars.
A wrong angulation results in a distorted
radiograph. Too little vertical angulation elongates the
radiographic image (fig. 1-27); too much vertical
angulation foreshortens the image (fig. 1-28).
A standard vertical angulation cannot be used for
all patients because of differences in their oral
1-18
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