Intraoral Occlusal Radiography
Maxillary Topographical Occlusal
This projection (Figure 63) shows the palate (roof of the mouth), zygomatic process of the maxilla (a projection from the maxilla), antero-inferior aspects of each antrum (in this case, the maxillary sinuses), nasolacrimal canals (tear ducts), teeth from the left second molars to the central incisors, and the nasal septum (cartilage dividing the nose).
Figure 63
Uses: To view the maxilla for anterior alveolar fractures, cysts, supernumerary teeth and impacted canines, and to view pathology at the apices of the incisors. It is not used to diagnose peridontal conditions.
Patient positioning: The patient is seated with the sagittal plane perpendicular to the floor and the occlusal plane parallel to the floor. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Film placement: With the tube side of the film (size #4) toward the maxilla, the film is placed crosswise in the mouth, like a sandwich. It is gently pushed backwards until it contacts the anterior border of the mandibular ramus. The patient bites down gently to maintain position.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The central ray is directed at the center of the film with a vertical angulation of +65 degrees and a horizontal angulation of 0 degrees. In this case, the central ray will pass through the bridge of the nose, as in Figure 64.
Figure 64
Mandibular Topographical Occlusal
Uses: To view the anterior portion of the mandible for fractures, cysts, root tip and periapical pathology. It provides a very good view of the symphysis region of the mandible. (Figure 65)
Figure 65
Patient positioning: The patient is seated with the head tilting slightly backward, so that the occlusal plane (ala-tragus line) is 45 degrees above the horizontal plane. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Film placement: With the tube side of the film (size #4) toward the mandible, the film is placed crosswise in the mouth, like a sandwich. It is gently pushed backwards until it contacts the anterior border of the mandibular ramus. The patient bites down gently to maintain position.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The central ray is directed between the apices of the mandibular central incisors and the tube is angled at -55 degrees relative to the film plane, as in Figure 66.
Figure 66
Maxillary Vertex Occlusal
Uses: To view the buccopalatal relationships of unerupted teeth in the dental arch. (Figure 67)
Figure 67
Patient positioning: The patient is seated with the sagittal plane perpendicular to the floor and the occlusal plane parallel to the floor. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Film placement: The film (size #4) is placed in the same manner as the Maxillary Topographical Occlusal.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The central ray is directed through the top of the skull (hence the name vertex occlusal). Since the beam must penetrate a considerable amount of bone and soft tissue, the exposure time must be increased. The central ray is perpendicular to the film plane and is directed to the center of the film as in Figure 68.
Figure 68
Mandibular Cross-Sectional Occlusal
Uses: To view the entire mandible for fractures, foreign bodies, root tips, salivary calculi, tori, etc. (Figure 69)
Figure 69
Patient positioning: The patient’s head may be in any comfortable position that allows the central ray to be directed perpendicular to the plane of the film packet. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Film placement: The film (size #4) is placed in the same manner as the Mandibular Topographical Occlusal.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The central ray is perpendicular to the film plane and is directed to the center of the film as in Figure 70.
Figure 70
Posterior Oblique Maxillary Occlusal
Uses: To view the maxillary posterior region and provide a topographical view of the maxillary sinus. The projection may be used in place of periapical films in patients who have a tendency to gag and for examining periapical pathology and root tips. (Figure 71)
Figure 71
Patient positioning: The patient is seated with the occlusal plane parallel to the floor and the sagittal plane perpendicular to the floor. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Film placement: The film (size #4) plane should be parallel to the floor, and the packet should be pushed posteriorly as far as possible. The lateral border of the film should be positioned parallel to the buccal surfaces of the posterior teeth and extend laterally approximately one-half inch past the buccal cusps on the side of interest. The patient should bite down gently to maintain film position.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The tube is directed at right angles to the curve of the arch, and strikes the center of the film packet as in Figure 72.
Figure 72
Posterior Oblique Mandibular Occlusal
Uses: The projection is used to view the posterior teeth of the mandible to locate cysts, fractures, supernumerary teeth, and periapical pathology. It can be used in place of posterior periapical films. (Figure 73)
Figure 73
Patient positioning: The patient is seated with the occlusal plane parallel to the floor and the sagittal plane perpendicular to the floor. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Film placement: The film (size #4) plane should be parallel to the floor, and the packet should be pushed posteriorly as far as possible. The lateral border of the film should be positioned parallel to the buccal surfaces of the posterior teeth and extend laterally approximately one-half inch past the buccal cusps on the side of interest. The patient should bite down gently to maintain film position.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The tube is directed at the apex of the mandibular second premolar, and the central ray should strike the center of the film packet. The vertical angulation is -50 degrees as in Figure 74.
Figure 74
Modified Oblique Posterior Mandibular Occlusal
Uses: This projection is especially useful to detect calculi in the submandibular gland. Calculi are often difficult to detect on conventional radiographs due to superimposition of the mandibular bone. (Figure 75)
Figure 75
Patient positioning and film placement: With the tube side of the film (size #4) toward the mandible the film is placed in the patient’s mouth crosswise like a sandwich. The film plane should be parallel to the floor, and the packet should be pushed posteriorly as far as possible. The lateral border of the film should be positioned parallel to the buccal surfaces of the posterior teeth and extend laterally approximately one-half inch past the buccal cusps on the side of interest. The patient’s head is then rotated to the side and lifted up. Before any radiographs are exposed, the patient must be protected with a lead apron and thyroid collar. The apron must be properly placed to avoid interference with the radiographic exposure.
Exposure factors: Follow the recommendations of the film and equipment manufacturer.
Direction of the central ray: The tube is positioned under and behind the mandible and the central ray is directed onto the center of the film so that it passes inside the ascending ramus so that the submandibular gland will be between the tube and the film as in Figure 76.
Figure 76
