How to incorporate dental radiology into your practice - DVM
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How to incorporate dental radiology into your practice


Figure 6: Bisecting angle technique.
Tube/film/patient positioning For the maxillary views, the patient is positioned in sternal recumbency with support placed under the chin at a height where the muzzle is parallel to the tabletop:

  • Incisors: Place the film packet toward the tube head against the incisors and palate. Position the PID perpendicular to an angle bisecting the film and teeth planes (Figure 5).
  • Canine: Place the film packet facing the tube, between the tongue and maxilla beneath the canine tooth root. Center the PID over the mesial root of the second maxillary premolar, dorsally or laterally depending on the view needed.

Figure 7: Maxillary premolar tube position.
Determine the angle between the plane of the canine root and the plane of the film. Position the cone perpendicular to the bisected angle (Figure 6).

  • Premolars: Place the film packet as close as possible to the inner surface of the cheek teeth. Aim the PID at the roots of the premolars at approximately 45-degrees.

Figure 8: Maxillary molar tube and film position.
The maxillary fourth premolar has three roots (mesial buccal, mesial palatal and distal). To avoid overlap of the mesial buccal and palatal roots, position the PID 20-degrees in the horizontal plane (rostral oblique) in the medium- to long-muzzled dog, and caudal oblique in brachycephalic breeds. In cats, the zygomatic arch is superimposed over the maxillary fourth premolar root. To avoid the arch, use a rostral oblique bisecting angle projection, aimed at the premolar roots with the PID positioned just ventral to the arch. Alternatively, extraoral near-parallel technique may be used to visualize the maxillary cheek teeth (Figure 7).

  • Molars: Place the film packet against the maxilla beneath the molar teeth. Aim the PID at the eye and film in a caudoventral direction (Figure 8).

Figure 9: Mandibular incisor position.
When radiographing the mandible, place the patient in ventral or lateral recumbency with support under the neck to place the muzzle parallel to the tabletop.

  • Incisors: Position the film packet toward the tube head against the incisors and the lingual frenulum. Position the PID perpendicular to the bisecting angle (Figure 9).
  • Canine: Place the patient in ventral recumbency. Position the film between the tongue and mandible, pushing the lingual frenulum distally. To obtain a lateral view, position the PID approximately 45 toward the canine (Figure 10).
  • Anterior premolars: Place the patient in lateral recumbency, with the film against the anterior premolars to include the periapical area. Aim the PID at the apex of the first premolar 20 degrees to the ventral border of the mandible (Figure 11).
  • Posterior premolars and molars: Place the patient in lateral recumbency. Position the film at the floor of the mouth lingual to the premolars. Place gauze or a hemostat to help depress the film into the floor of the mouth. Aim the PID perpendicular to the tooth roots and film (parallel technique) larger teeth, survey studies, and maxillary occlusal views in dogs and cats (Figure 12).

Figure 10: Mandibular canine tube and film position.
Film may be developed in the following ways:

Manually, using developer, water and fixer solutions in the practice darkroom.

Figure 11: Position of film and tube head to expose mandibular premolars.
With the chairside darkroom, a portable light-safe box containing rapid developer, distilled water and fixer in small containers is placed in the dental operatory. The chair- side darkroom is covered with a plexiglas safety filter, which enables operators to see their hands while handling the film(s). The filter is either amber (when D speed film is exposed), or red (for E or F speed films). Processing time from opening the film packet to initial examination of a rinsed film takes approximately two minutes (Figure 13).

Using an automatic dental processor (preferred by author) delivers dry films in six minutes.

Manual processing Manual processing includes the following steps:

Figure 12: Position of film and tube head for exposure of mandibular molars.
1. After exposure, carry the film into the practice darkroom or chairside darkroom for processing. Slide the film packet tab down to present film, cardboard and lead blocker. The film will feel firm to the touch, compared to the other film pack contents.

2. A film hanger is attached to the film edge. Touch only the sides of the film with fingers. Apply a gentle tug to make certain the film is firmly attached to the clip.

3. Place the film in prestirred developer solution for the specified time recommended by the manufacturer (Kodak Rapid Access Chemistry: 15 seconds at 68-degrees). Note: an alternative method starts manual film processing with water immersion to soften the emulsion before placement in the developer.

Figure 13: Manual chairside darkroom.
4. After placement in the developer, rinse the film in fresh distilled water (wash) for 10-15 seconds. Rinsing removes the alkaline developer from the film surface, preventing mixture with the acid fixer.

5. Place the film in the prestirred fixing solution for at least two minutes. Fixer removes the unexposed or underdeveloped silver halide crystals and rehardens the emulsion.

6. Rinse the film for 30 seconds in distilled water.

7. After viewing, place the film back in the fixer for five minutes, followed by distilled water rinse for 10 minutes.

Real world logistics
8. When rinsing is complete, attach the radiograph to a clip on the drying rack. Dental radiology is as important to patient dental care as radiology in any other organ system. The information gained is crucial to perform quality dentistry. The next article will concern evaluating dental films to help formulate a dental treatment plan.


Source: DVM360 MAGAZINE,
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