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TOday'S VeTerinary PracTice | September/October 2015 | tvpjournal.com PracTical denTiSTry Peer reviewed 62 Simplifed Technique The simplifed technique 2,11 does not require direct measurement of any angle, but instead relies on the approximate angle between the position indicating device (Pid) and sensor/plate to create diagnostic images. There are only 3 angles used for all radiographs in this system: 45, 70, and 90 degrees. • Mandibular premolars/molars: exposed at a 90-degree angle; the film is parallel, while the beam is perpendicular (parallel technique, Figure 6 ) • Maxillary premolars/molars: These roots are typically straight and parallel with the visible crown, and the sensor/plate lies essentially flat across the palate, creating an approximate 90-degree angle that, when bisected, indicates that all maxillary premolars and molars be imaged at a 45-degree angle (Figure 10). • canines/incisors: These teeth curve caudally at an approximate 40-degree angle to the palate/ body of the mandible; therefore, they are imaged with a 70-degree angle rostrocaudal (bisecting the 40-degree angle equals 20; when 20 is subtracted from 90, it indicates that the angle should be 70 degrees from perpendicular to the sensor/plate) (Figure 11). Figure 10. Proper bisecting angle for the maxillary premolars and molars of a dog: The PiD is set 45 degrees to the sensor, which provides an excellent image of all premolars and molars (a). Note that, when using a size 2 sensor, multiple images are often necessary. in this patient, the frst and second premolars (B) and fourth premolar (c) are in separate images. The mesial roots of the maxillary fourth premolar are overlapped (red arrows). in order to visualize these roots separately, the mesial or distal tube shift is required (figures 15 and 16, page 66). A B C Figure 9. Foreshortening: The bisecting angle for the maxillary premolars and molars is 45 degrees to the sensor. in this photo, the PiD has been set up at approximately 65 degrees ( a). The resulting image (B) demonstrates foreshortening of the tooth roots. To fx this error, rotate the tube head to a more parallel position to the sensor. A B