and third molars in dog: position sensor/film further caudally, but also dorsally; don’t let it slide ventrally (keep in place with perm roller). Aim beam from a position caudal and dorsal to the film, using the tape roll to assist; this will “cast the shadow” or “push” the teeth onto the image.Aim beam from a position caudal and dorsal to the film. This will “push” the teeth onto the image, using the tape roll to assist (cast the shadow onto the film) (Figure 3.24).
Maxillary premolars of cats and brachycephalic dogs.Keep mouth open with perm roller or 30‐mm clear mouth gag [9], place sensor/film under the maxillary premolars on the downside, slightly dorsal to the teeth (Figure 3.25).Aim beam from above and caudally, at a slight oblique, so the image of the “downside” maxillary premolars will be projected on the film underneath (follow the beam), and the “upside” maxillary teeth will not be superimposed (Figure 3.26). Mark the image as extraoral for later identification purposes.Note: since the beam is further from the film than in an intraoral method, additional exposure time may be necessary.
Figure 3.25 Maxillary premolars of cats and brachycephalic dogs: keep mouth open with perm roller or 30‐mm clear mouth gag. Place sensor/film under the maxillary premolars on the “downside,” more dorsal to the teeth.
Figure 3.26 Aim beam from above and caudally, at a slight oblique, so the image of the “downside” maxillary premolars will be projected on the film underneath (follow the beam), and the “upside” maxillary teeth will not be superimposed. Note or mark the film as extraoral for later identification purposes.
Preparing Images and Films
An additional advantage of direct digital radiography is being able to immediately adjust the positioning of an image, or to adjust the amount of exposure.
For images through the maxilla, of apical regions, or extraoral views, higher exposure times might be necessary to get sufficient clarity.
For images through thinner bone, or to accurately assess the extent of periodontal bone loss, shorter exposure times might be necessary (Figure 3.27).
The Sopix digital dental sensor has the widest latitude of exposure, minimizing the need for exposure adjustments [4].
Figure 3.27 (a) Radiograph of right maxillary fourth premolar and first molar shows apparent significant periodontal bone loss, but crown density is also light, an indication of possible overexposure. (b) Repeat radiograph of maxillary premolar with decreased exposure shows moderate bone loss, a more accurate assessment. The Sopix sensor often accommodates to account for exposure issues.
RADIOGRAPHIC INTERPRETATION STEPS (Figure 3.28)
Orientation of Films
Standard intraoral film positioning and viewing (nondigital films will have the embossed “dot” coming out towards you).
Decide if the image is maxillary or mandibular.Maxillary: is there a white line formed by the dorsal plate of the alveolar process of the maxilla (see Figure 3.30)? (Remember, typically the only three rooted teeth are in the maxilla.)Mandibular: is the mandibular canal seen?
Position the image with the crowns “in the mouth” like a Cheshire cat grin (mandibular roots pointing down, maxillary roots pointing up) (Figure 3.29).
Identify side:For canines and incisors: “shake hands” – image’s right is on your left and image’s left is on your right (see Figure 3.28).For premolars: determine “which way is the nose”; is the rostral aspect of the image toward your right or toward your left (Figure 3.30)?Exception: for any extraoral film, right and left will be opposite as compared to an intraoral film (Figure 3.31).
Evaluation of Films
Note Any Missing or Deciduous Teeth
Utilizing the Triadan numbering system, the mouth is divided into quadrants.Remembering the mantras, “Do it right the first time” and “Always do your best/Be on top,” the top right quadrant is the 100s.As you look at the patient, the quadrants proceed clockwise (see Figure 3.29):Maxillary left quadrant is the 200s.Mandibular left quadrant is the 300s.Mandibular right quadrant is the 400s.
Number from midline in each quadrant proceeding to the last molar:Incisors are _01 through _03.Figure 3.28 A summary of the simple steps to complete when interpreting radiographic film. The image shows dog mandibular incisors and canines, with missing lower right first incisor (401) and both first premolars (305, 405).Figure 3.29 Orient films with the crowns “in the mouth” like a Cheshire cat grin, with mandibular roots pointing down, maxillary roots pointing up. Triadan quadrant numbering begins in the top right and proceeds clockwise.Canines are always _04.Premolars are _05 through _08:The large upper carnassial tooth is the fourth premolar = 1/208.Cats do not have any _05s nor lower _06s.Molars are _09 up to _11 when present:The large lower carnassial tooth is the first molar = 3/409.Normally the last maxillary tooth in the dog is 1/210.Figure 3.30 Reading a radiograph. With premolars and molars, determine “where is the nose”; if the rostral aspect of the image is to the left, then the teeth are from a left quadrant. Images show left maxilla in a dog: note the white line formed by the dorsal plate of the alveolar process, present only in the maxilla.Figure 3.31 An extraoral film is read in the opposite way: right and left will be reversed compared to an intraoral film. Image shows left maxillary premolars in a cat (even though the nose is to the right).Normally the last mandibular tooth in the dog is 3/411.There is only M1 in each quadrant of the cat = _09.
Deciduous