Section III. FAULTY RADIOGRAPHS
Errors in improperly exposing or processing dental films can produce undesirable dental radiographs of nondiagnostic quality. These are known as faulty radiographs. The dental x-ray specialist should be familiar with the common causes of faulty radiographs and how to prevent them.
3-10. UNDEREXPOSED IMAGE
An underexposed image (see figure 3-11), an image that is too light, may be caused by:
- Insufficient radiation exposure.
- Insufficient development time.
- Use of an overused developing solution.
- Use of a developing solution that is too cold.
Figure 3-11. Underexposed image.
3-11. OVEREXPOSED IMAGE
An overexposed image (see figure 3-12), an image that is too dark, may be caused by:
- Too much radiation exposure.
- Too much development time.
- Use of developing solution that is too warm.
Figure 3-12. Overexposed image.
3-12. BLURRED IMAGE
A blurred image (see figure 3-13) is easily recognized by the appearance of more than one image of the object, or objects, on the film. It may be caused by movement of the patient, film, or tube during exposure.
Figure 3-13. Blurred image.
3-13. PARTIAL IMAGE
A partial image (see figure 3-14) may be caused by failure to immerse the film completely in the developing solution, contact of the film with another film during developing, or improper alignment of the central ray.
Figure 3-14. Partial image.
3-14. DISTORTED IMAGE
A distorted image (figure 3-15) may be caused by improper angulation of the central ray due to bending of the film packet.
Figure 3-15. Distorted image.
3-15. FOGGED FILM
Fogged film ( figure 3-16) may be caused by:
- Exposure of film to light during storage.
- Leaving film unprotected (that is, outside the lead-lined box or in the x-ray room during operation of the x-ray machine).
- Use of film that has been exposed to heat or chemical fumes.
- Use of improperly mixed or contaminated developer.
- Defective safelight.
Figure 3-16. Fogged film.
3-16. STAINED OR STREAKED FILM
Stained or streaked film ( figure 3-17) may be caused by dirty solutions, dirty film holders or hangers, incomplete washing, or solutions left on the workbench.
Figure 3-17. Stained or streaked film.
3-17. BLEACHED IMAGE
A bleached image (see figure 3-18) is caused by leaving the film in a freshly-mixed fixing solution too long or at a temperature that is too warm.
Figure 3-18. Bleached image.
3-18. LEAD-FOIL IMAGE
A lead-foil image (see figure 3-19) occurs when the embossing pattern from the lead foil backing appears on the radiograph. The embossing pattern consists of raised diamonds across both ends of the film. This happens when the film is put in backwards.
Figure 3-19. Lead-foil image.
3-19. NO IMAGE
No image may result if no current was passing through the tube at the time of exposure or if the film was placed in the fixing solution before it was placed in the developing solution.
A reticulated film appears as a network of wrinkles or corrugations on the emulsion of the x-ray film. When reticulation occurs, the finished film has a netlike or puckered appearance resulting from swelling of the film's gelatin. Swelling is caused by sudden changes in temperature during processing, as in the transfer from a cool fixing bath to warm wash water or from a warm rinse water to a cool fixing bath.
Section IV. MOUNTING AND FILING/DISPOSING OF RADIOGRAPHS
Cardboard or plastic mounts for 16-film, full-mouth radiographs and bite-wing mounts are available as standard items of dental supply. Sections of these, or small paper envelopes, are used for protecting and identifying individual periapical or bite-wing radiographs. The film mounts are designed so that the film may be arranged in the same order as the teeth in the mouth. Thus, mounting not only protects and labels the radiographs, but also facilitates viewing and studying of the film, particularly in full-mouth examinations. See figure 3-20.
Figure 3-20. Full-mouth radiographic mount.
In mounting radiographs, care must be taken to avoid marks from damp or perspiring fingers. Hands and fingers should be clean and dry. The film should be handled only on the edge. Under adequate illumination, the radio- graphs are removed one at a time from the hanger and placed carefully into the appropriate opening in the film mount. Radiographs are mounted so that the raised part of the embossed dot faces the dental specialist. In this way the radiographs are viewed from the facial aspect in correct anatomical order.
- Maxillary and mandibular radiographs may be identified by the anatomy of the teeth and surrounding structures. (See paragraphs 3-24 through 3-28 for anatomic landmarks.) Radiographs are mounted with apices of maxillary teeth directed upward and apices of mandibular teeth directed downward.
- The mesial aspect of a radiograph may also be determined by the anatomic features of tissues included on the film. If the mesial is to the right (when viewed from the facial side), it is a film taken on the patient's right side. If the mesial is to the left (when viewed from the facial side), it is a film taken of the patient's left side.
3-23. FILING AND DISPOSING
Dental radiograph holders or containers should be identified with the patient's name, address and other pertinent information, such as date and teeth, or area, included in the films.
- The Dental Health Record. Dental radiographs needed for future treatment or follow-up observation of a patient are kept in the dental health record.
- Disposition of Radiographs. Some radiographs may be kept for extended periods if the dentist deems necessary. These radiographs may serve as history with regard to future treatment of the patient.
Section V. ANATOMIC RADIOGRAPHIC LANDMARKS
A number of anatomic landmarks are visible in dental radiographs. Knowledge of the location and normal appearances of these landmarks is important in identification and orientation of radiographs. This knowledge is valuable to the dentist in determining whether the area is normal or abnormal. The landmarks that appear as dark areas on the film are radiolucent. The areas that appear as light areas on the film are radiopaque. Anatomic characteristics and the relationship between individual teeth are anatomic landmarks with which all dental specialists should be familiar.
3-25. RADIOLUCENT LANDMARKS ON MAXILLARY RADIOGRAPHS
- Maxillary Sinus. The maxillary sinus (see figure 3-21) is a very prominent radiolucent structure. It sometimes appears as overlapping lobes or a single radiolucent area with a radiopaque border. The maxillary sinus is partially seen in all periapical radiographs of the bicuspid-molar area. It occupies a large part of the body of the maxilla, varying greatly in dimension, but normally extending into the alveolar process adjacent to the apices of the posterior teeth.
- Incisive Foramen. The incisive foramen (see figure 3-22) is seen as a dark area located between and extending above the central incisors. In radiographs exposed from the region of the cuspid or lateral incisor, the incisive foramen may appear as a radiolucency at the apex of one of the incisors.
Figure 3-21. Maxillary Sinus.
Figure 3-22. Incisive foramen.
- Median Palatal Suture. The median suture of the palate (see figure 3-23) may appear as a radiolucent line extending posteriorly from the alveolar border in the sagittal plane of the maxilla, on an anterior periapical film, or occlusal film.
- Nasal Fossae. In a radiograph of the maxillary central incisors, the images of the paired fossae appear as somewhat elliptical radiolucent areas of various sizes separated by a radiopaque band representing the nasal septum (see figure 3-24).
Figure 3-23. Median palatal suture.
Figure 3-24. Nasal fossae.
3-26. RADIOPAQUE LANDMARKS ON MAXILLARY RADIOGRAPHS
- Maxillary Tuberosity. The maxillary tuberosity (see figure 3-25) is the convex distal inferior border of the maxilla, curving upward from the alveolar process and distal of the third molar. An extension of the maxillary sinus is occasionally seen within the maxillary tuberosity.
- Coronoid Process of the Mandible. The coronoid process of the mandible (see figure 3-26) sometimes appears on maxillary molar films as a triangular opaque area located in the region of or distal to the maxillary tuberosity.
Figure 3-25. Maxillary tuberosity.
Figure 3-26. Coronoid process of the mandible.
- Zygomatic Process (Malar Bone). The zygomatic arch (see figure 3-27) commonly appears as a well-defined radiopaque area that may be superimposed over the molar roots. Additional radiographs are sometimes made at adjusted angulation to provide a better view of the molar root area.
Figure 3-27. Zygomatic process (malar bone).
- Nasal Septum. The nasal septum is usually seen as a white ridge extending above and between the central incisors.
3-27. RADIOLUCENT LANDMARKS ON MANDIBULAR RADIOGRAPHS
- Mandibular Foramen. The mandibular foramen is seen on extraoral mandibular films as a dark area near the middle of the mandibular ramus.
- Mandibular Canal. The mandibular canal (see figure 3-28) appears as a dark band with radiopaque borders running downward and forward from the mandibular foramen in the ramus to the region of the bicuspid teeth in the body of the mandible. It may be seen below the roots of the posterior teeth.
Figure 3-28. Mandibular canal.
- Mental Foramen. The mental foramen (see figure 3-29) is seen as a dark area below and between the bicuspids. Since it is not contiguous with either bicuspid, its relationship to these teeth appears different on radiographs made at different angulations.
3-28. RADIOPAQUE LANDMARKS ON MANDIBULAR RADIOGRAPHS
- Border of the Mandible. The border of the mandible is seen as a heavy white line (see figure 3-30). A similar line does not appear on maxillary radiographs.
- External Oblique Ridge. The external oblique ridge is a white line of variable density extending into the molar region as a continuation of the anterior border of the ramus of the mandible (see figure 3-31).
Figure 3-30. Border of the mandible.
Figure 3-31. External oblique ridge.
- Genial Tubercles. Genial tubercles are seen as round white areas, having dark centers, located below and between the central incisors (see figure 3-32).
Figure 3-32. Genial tubercles.
- Mental Process (Mental VRidge). The mental ridge may appear as a dense white ridge of varying density extending from the anterior midline to the bicuspid region, usually located below the anterior teeth, but occasionally superimposed over the apices.
- Mylohyoid Ridge (Internal Oblique Ridge). The mylohyoid ridge appears as a white line of varying width and indensity, extending from close to the lower border of the symphysis of the mandible, upward and distally, to end beyond the third molar. It reaches its greatest prominence in the molar region. It is generally not a prominent feature.