4-9.
OVERVIEW OF THE BISECTING ANGLE EXPOSURE TECHNIQUES
a. The bisecting method of periapical radiography is used to varying degrees in
Army dental clinics. The dental specialist should be familiar with its techniques. The
following paragraphs describe techniques using this method to produce a 14-exposure
set of radiographs of an adult dentition. Discussion of the techniques for exposure of
each area of the mouth will include illustrations and descriptions of film placement, film
holding, direction of the central ray, and average angulation. Slight contouring of a
corner may facilitate film placement in restricted areas of the mouth, such as those of
the maxillary incisors or the maxillary third molar, and make it more comfortable. To
shape the film, press it over the rounded contour of a finger to pre-adapt it to the
position in the mouth. Use only slight contouring to prevent distortion of the image. (A
flat image produces the best image). Paragraph 4-7 covers proper head positioning
b. Various film holding devices may be used to secure the film in place when
using the bisecting technique: the Rinn EEZEE-GRIP Film Holder, a hemostat, a plastic
or Styrofoam film holder (with a 105-degree angle) (see figure 4-9). When such film
holding devices are not available, the finger or thumb may be used.
Figure 4-9. Film holding devices for the bisecting technique.
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