Horizontal Angulation: I am using a rod and ring aiming system. How do I know if I can follow the aiming ring?
The operator has identified the position of the marginal ridges and the horizontal angulation. With the sensor holder positioned in the mouth, the operator critiques the position of the sensor, and the aiming rod’s position. Is the aiming rod parallel to the marginal ridges? Is there active sensor in this path? If YES, the aiming ring can be followed in the horizontal plane. Look at the contacts between teeth whenever setting the horizontal angulation of the PID (Figure 7).
Figure 7 - Premolar Periapical Horizontal Angulation: Can I follow the aiming ring?
(A) Confirm aiming rod is parallel with the marginal ridge. (B) Confirm active sensor behind the canine in the radiation's path. (C) Looking through the aiming ring. (D) Confirm the PID's position equal gap with the aiming ring.
If NO, try to re-position the sensor holder to find parallel alignment. If parallel alignment is not possible, the aiming ring should not be followed in the horizontal plane. The PID should be positioned independent of the ring and placed parallel with the marginal ridges of the teeth (Figure 8). Make sure active sensor is in the path created.
Figure 8 - Horizontal Angulation
The PID is following the marginal ridges of the teeth, and is not aligned with the aiming ring.