2. Learning Objectives
Lesson 21.1: Occlusal
and Localization Techniques
1. Define the key terms associated with occlusal and localization
techniques.
2. Describe the purpose of occlusal examination.
3. List the uses of occlusal examination and discuss the basic principles
involved.
4. Describe the patient and equipment preparations that are necessary
before using the occlusal technique.
5. State the recommended vertical angulations for the following maxillary
occlusal projections: topographic, lateral (right or left), and pediatric.
2
3. Learning Objectives
Lesson 21.1: Occlusal
and Localization Techniques
(Cont.)
6. State the recommended vertical angulations for the following
mandibular occlusal projections: topographic, cross-sectional, and
pediatric.
7. State the purpose of localization techniques and list their uses.
8. Describe the buccal object rule.
9. Describe the right-angle technique.
10. List the patient and equipment preparations that are necessary
before using the buccal object rule or the right-angle technique.
3
4. Learning Objectives
Lesson 21.1: Occlusal
and Localization Techniques
(Cont.)
11. Describe receptor placements for the buccal object
rule and compare the resulting images.
12. Describe receptor placements for the right-angle
technique and compare the resulting images.
4
5. Introduction
Purpose of this chapter
To present basic concepts
To describe patient preparation, equipment preparation, and
film placement procedures for both the occlusal and
localization techniques
5
6. Occlusal Technique
Used to examine large areas of the maxilla or the
mandible
The technique is so named because the patient
bites, or “occludes” on the entire receptor.
6
7. Purpose and Use
A supplementary imaging technique used in
conjunction with periapical or bite-wing images
Used when large areas of the maxilla or mandible must
be visualized
Preferred when area of interest is larger than a
periapical receptor or when placement of periapical
receptors is too difficult for the patient
7
8. Purpose and Use continued…
Used to locate:
Retained roots of extracted teeth
Supernumerary teeth
Foreign bodies
Salivary stones
Fractures
Cleft palate
8
9. Principles
The receptor is placed with the tube side facing the
arch that is being exposed.
The receptor is placed in the mouth between the
occlusal surfaces of maxillary and mandibular
teeth.
The receptor is stabilized when the patient gently
bites on the surface of the receptor.
9
10. Patient Preparation
Explain the imaging procedure to the patient.
Adjust the chair so that the patient is positioned upright
and the level of the chair is at a comfortable working
height.
Adjust the headrest to support and position the patient’s
head.
Occlusal plane is to be parallel to the floor
Place the lead apron with thyroid collar on the patient
and secure it.
Request that the patient remove eyeglasses and any
objects in the mouth. 10
11. Equipment Preparation
Set the exposure control factors on the x-ray unit
according to the recommendations of the receptor
manufacturer.
Either a short (8-inch) or a long (16-inch) position-
indicating device (PID) may be used with the occlusal
technique.
11
12. Maxillary Occlusal Projections
Topographic projection (in Lab)
Used to examine the palate and the anterior teeth of the
maxilla
Lateral (left or right) projection
Used to examine the palatal roots of the molar teeth
Maxillary lateral projection may also be used to locate
foreign bodies or lesions in the posterior maxilla
Pediatric projection
Used to examine the anterior teeth of the maxilla,
recommended for use in children 5 years old or younger
12
13. Mandibular Occlusal
Projections
Topographic projection (in Lab)
Used to examine the anterior teeth of the mandible
Cross-sectional projection
Used to examine the buccal and lingual aspects of the
mandible
May also be used to locate foreign bodies or salivary stones
in the region of the floor of the mouth.
Pediatric projection
Used to examine the anterior teeth of the mandible,
recommended for use in children 5 years old or younger13
15. Maxillary Topographic
Occlusal Projection
1. Position the patient with maxillary arch parallel to the floor
2. Place a size 4 receptor with the tube side facing the maxilla and
the long edge in a side-to-side direction, Insert the receptor into
the patients mouth, placing it is far posteriorly as the oral anatomy
permits
3. Instruct the patient to bite gently on the receptor, and hold the
receptor in an end-to-end bite
4. Position the PID with the CR directed through the midline of the
arch toward the center of the receptor
5. Position the PID at +65 degrees VA toward the center of the
receptor. Place the top edge of the PID between the patient's
eyebrows on the bridge of the nose 15
16. A. The central ray (CR) is directed at +65
degrees vertical angulation to the plane of the
receptor.
16
19. Mandibular Topographic
Occlusal Projection
1. Position the patient with the mandibular arch parallel to the
floor
2. Place a size 4 receptor film with the tube side facing the
mandible and the long edge in a side-to-side direction. Insert
the receptor into the patient’s mouth, placing it as far
posteriorly as the oral anatomy permits.
3. Instruct the patient to bite gently on the receptor, and hold
the receptor in an end-to-end bite.
4. Position the PID with the central ray directed through the
midline of the arch toward the center of the receptor
5. Position the PID at -55 degrees VA toward the center of the
receptor. Center the PID over the patient’s chin. 19
20. A. The central ray (CR) is directed at -55
degrees vertical angulation to the plane of
the receptor.
20
23. Localization Techniques
A method used to locate the position of a tooth or
object in the jaws
A thorough understanding of basic concepts is necessary.
A knowledge of step-by-step procedures is required.
23
24. Purpose and Use
The dental image is a two-dimensional picture of
a three-dimensional object.
It does not depict the depth of the object.
Localization techniques can be used to locate the
object
Used to locate a foreign object or impacted
tooth, within the jaws
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25. Purpose and Use (Cont.)
Localization techniques may be used to locate the
following:
Foreign bodies
Impacted teeth
Unerupted teeth
Retained roots
Root positions
Salivary stones
Jaw fractures
Broken needles and instruments
Dental restorative materials 25
26. Buccal Object Rule
Governs the orientation of structures portrayed in
two images exposed at different angulations
One periapical or bite-wing receptor is exposed using
proper technique and angulation.
A second periapical or bite-wing receptor is exposed after
changing the direction of the x-ray beam.
After the first image has been taken, a different horizontal or
vertical angulation is used.
After both images are exposed and processed, they are
compared with each other.
26
27. 27
When the dental
structure or object
seen in the second
image appears to
have moved in the
same direction as the
shift of the PID, the
structure or object in
question is
positioned to the
lingual.
Blue dot = buccal
Black dot = lingual
28. 28
When the dental
structure or object
seen in the second
image appears to
have moved in the
opposite direction
as the shift of the
PID, the structure
or object in
question is
positioned to the
buccal.
29. Buccal Object Rule (Cont.)
A mnemonic: SLOB
S = same
L = lingual
O = opposite
B = buccal
When two images 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.
29
30. Right-Angle Technique
Another rule for the orientation of structures seen on
images
One periapical receptor is exposed using the proper technique
and angulation to show the position of an object in the
superior-inferior and anterior-posterior relationship.
An occlusal receptor is exposed directing the central ray
perpendicular to the receptor.
The images are compared to locate the object in three
dimensions.
This technique is primarily used to locate objects in the
mandible.
30
32. 32
A. Note the two root canals filled with gutta percha in
the maxillary second premolar (arrow). B. The PID
was shifted in a mesial direction, so the gutta percha
moved in a distal direction. The gutta percha in the
original root labeled by the arrow is located on the
buccal
33. 33
A. Note the impacted tooth (arrow). B. The
position-indicating device (PID) was shifted in a
distal direction, so the tooth moved in a distal
direction. The tooth is located lingual to the
adjacent teeth.
Editor's Notes
In addition to mastering periapical and interproximal examination techniques, the dental radiographer must also master occlusal and localization techniques.
The technique is so named because the patient bites, or “occludes” on the entire receptor.
Used to locate:
Retained roots of extracted teeth
Supernumerary teeth
Foreign bodies
Salivary stones
Fractures
Cleft palate
It is important to stress to the patient to gently bite on the receptor to avoid seeing permanent bite marks on the surface of the sensor.
Be sure the occlusal plane is parallel to the floor.
The patient should be in an upright position.
Patient should gently bite down; otherwise the patient can damage the receptor.
Refer student to Procedure 21-1.
After patient preparation, equipment must also be prepared before the exposure of any images.
Exposure control factors include kilovoltage, milliamperage, and time.
Refer students to Procedure 21-2.
The maxillary lateral occlusal projection may also be used to locate foreign bodies or lesions in the posterior maxilla.
Refer students to Procedures 21-3 through 21-5.
The mandibular cross-sectional occlusal projection may also be used to locate foreign bodies or salivary stones in the region of the floor of the mouth.
Refer students to Procedures 21-6 through 21-8.
Refer students to Table 21-1.
The dental image is a two-dimensional picture of a three-dimensional object.
Used to locate a foreign object or impacted tooth, within the jaws.
Used to locate a foreign object or impacted tooth, within the jaws.
After the first image has been taken, a different horizontal or vertical angulation is used.
After both images are exposed and processed, they are compared with each other.
When two images 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.
This technique is primarily used to locate objects in the mandible.
The occlusal image shows the object in the buccal-lingual and anterior-posterior relationships.
Refer students to Figure 21-9.
