Horizontal Angulation: How do I know that the distal canine crown will appear on the premolar periapical image?

You must identify the correct horizontal angulation, and when standing in that path, make sure the active part of the sensor is physically within the radiation’s path. In Figure 9B, the photograph was created when standing in the correct horizontal angulation to capture the distal canine crown and to open the contacts around the first premolar. We can see active sensor positioned behind the canine #22 (within the green circle). The distal half of canine #22 and the premolars appear in the periapical image. In Figure 10, canine #22 does not appear in the image. Looking through the aiming ring, we see the sensor’s dead zone behind the canine. This can be difficult to correct. Keep reading and find solutions in Problem #3.

Figure 9 - Premolar Periapical
(A) Image with required distal crown #22. (B) Verification of active sensor behind #22 within green circle.

Figure 9 - Premolar Periapical
(A) Image with required distal crown #22. (B) Verification of active sensor behind #22 within green circle.

Figure 10 - Premolar Periapical
(A) Image without required distal crown #22. (B) Deadzone behind #22 within red circle... tooth will not appear on the image.

Figure 10 - Premolar Periapical
(A) Image without required distal crown #22. (B) Deadzone behind #22 within red circle... tooth will not appear on the image.