Chapter 21: Occlusal and Localization Technique
- 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
- 14. Vertical Angulations Occlusal projection Vertical angulation Maxillary topographic +65 Maxillary lateral (rt or lt) +60 Maxillary pediatric +60 Mandibular topographic −55 Mandibular cross-sectional 90 Mandibular pediatric −55 14
- 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
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- 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
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- 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 24
- 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
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- 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
- #6: In addition to mastering periapical and interproximal examination techniques, the dental radiographer must also master occlusal and localization techniques.
- #7: The technique is so named because the patient bites, or “occludes” on the entire receptor.
- #8: Used to locate: Retained roots of extracted teeth Supernumerary teeth Foreign bodies Salivary stones Fractures Cleft palate
- #10: 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.
- #11: 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.
- #12: 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.
- #13: 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.
- #14: 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.
- #15: Refer students to Table 21-1.
- #24: The dental image is a two-dimensional picture of a three-dimensional object.
- #25: Used to locate a foreign object or impacted tooth, within the jaws.
- #26: Used to locate a foreign object or impacted tooth, within the jaws.
- #27: 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.
- #30: 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.
- #31: 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.