RAD Ch. 21: Occlusal Films
and
Buccal Object Rule
DA 118 Radiology
Purposes and Uses
of Occlusal Film
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Examine large areas of upper or lower jaw
Used in conjunction with periapical x-rays or
bitewing x-rays
White side of film positioned toward PID
No film holder; film is stabilized when patients
bites the film
Adult: Size 4; pediatric: Size 2
Edentulous Patient:
Periapical and Occlusal X-Rays
Why use an Occlusal Film?
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Locate retained roots of extracted teeth
Locate supernumerary, unerupted, or impacted teeth
Locate foreign bodies or salivary stones
Locate and evaluate extent of lesions (cysts, tumors)
Evaluate boundaries of the maxillary sinus
Evaluate fractures of maxilla or mandible
Examine area of cleft palate
Examination of patients with limited opening
Measure changes in size and shape of jaw
Maxillary Occlusal Films
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Patient head position: maxillary arch is
parallel to floor; midsagittal plane is
perpendicular to floor
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Topographic Projection
Lateral Projection
Pediatric Projection
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Maxillary Topographic Projection
Palate and anterior teeth
CR = +65
Size 4 film
Maxillary Lateral Projection
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Palatal roots of the
molars
Locate foreign bodies
or lesions in the
posterior maxilla
CR =+60
Size 4 film
Pediatric Projection
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Anterior teeth of the
maxilla
Recommended for
ages 5 and under
CR = +60
Size 2 film
Mandibular Occlusal Films
Position patient:
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Occlusal plane is perpendicular to floor OR
Occlusal plane is parallel to floor
Topographic Projection
Cross-Sectional Projection
Pediatric Projection
Topographic
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Anterior teeth of the
mandible
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CR = -55
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Size 4 film
Cross-Sectional Projection
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Buccal and Lingual
aspects of the mandible
Locate foreign bodies
or salivary stones in the
region of floor of the
mouth
CR = 90 (0)
Size 4 film
Pediatric Projection
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Anterior teeth of the
mandible
Recommended for use
in children ages 5 years
and under
CR = -55
Size 2 film
Localization Techniques
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Used to locate the position of a tooth of
object in the jaws
X-ray is a 2-dimensional image of a
3-dimensional structure; does not show the
depth of the structure
1.Buccal-Object Rule
2.Right-angle Technique
Buccal Object Rule
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Governs the orientation of structures
portrayed in two radiographs exposed at
different angulations
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One periapical or bite-wing film is exposed using
proper technique and angulation
A second periapical or bite-wing film is exposed
after changing the direction of the x-ray beam
TWO PERIAPICAL FILMS
Buccal Object aka “SLOB Rule”
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S = SAME
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L = LINGUAL
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O = OPPOSITE
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B = BUCCAL
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IF the structure or object
seen in the 2nd x-ray appears
to move in the same direction
as the PID, item is positioned
on the lingual
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If the structure or object seen
in the 2nd x-ray appears to
move in the opposite
direction as the PID, item is
positioned on the buccal
Same * Lingual
Opposite * Buccal
SLOB Rule
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When two radiographs are compared, the
object that lies to the lingual appears to have
moved in the same direction as the PID, and
the object that lies to the buccal appears to
have moved in the opposite direction as the
PID.
Right-angle Technique
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Another method to determine orientation of
structures.
One PA x-ray:
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One occlusal film:
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exposed using proper technique and angulation
shows the position in the superior-inferior, anteriorposterior relationship
exposed directing CR at right angle to the film;
shows the object in the buccal-lingual and anteriorposterior relationships
Primary use: locate objects in the mandible
Right-Angle Technique Example
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PAx-ray shows that
there is an object
located between the
first premolar and the
canine, subgingivally
Occlusal film indicates
that the object is on the
lingual aspect of the
mandible
Exercises # 11-14
Exercise #15