Intra 104

Film Holders

• Although you may see operators asking patients to hold the film with their fingers to stabilize the film in the mouth, it is not recommended. This practice exposes the patient’s hand and finger to unnecessary radiation. 
• The following are types of commercial film holders that are available: 
  • Rinn BAI 
  • Rinn Eezee-Grip Film Holder (Snap-A-Ray)
  • Rinn Stabe Bite-Block

PID Angulations: Bisecting Technique

• In the bisecting technique, the angulation of the PID is critical. 
• Angulation is a term used to describe the alignment of the central ray of the x-ray beam in the horizontal and vertical planes. 
• Angulation can be changed by moving the PID in either a horizontal or vertical direction. 
• BAIs with aiming rings dictate the proper PID angulation.

Horizontal Angulation

• Horizontal angulation refers to the positioning of the tubehead and direction of the central ray in a horizontal, or side-to-side, plane. 
• The horizontal angulation remains the same whether you are using the paralleling or bisecting technique.

The arrows indicate movement in a horizontal direction.

Correct Horizontal Angulation

• With correct horizontal angulation, the central ray is directed perpendicular to the curvature of the arch and through the contact areas of the teeth. 
• Incorrect horizontal angulation results in overlapped (unopened) contact areas. 
• A film with overlapped contact areas cannot be used to examine the interproximal areas of the teeth. 

Correct horizontal angulation. (From Iannucci J, Jansen Howerton L: Dental radiography: principles and techniques, ed 3, St Louis, 2006, Saunders.)

Incorrect horizontal angulation. (From Iannucci J, Jansen Howerton L: Dental radiography: principles and techniques, ed 3, St Louis, 2006, Saunders.)

Overlapped contact areas.

Vertical Angulation

• Vertical angulation refers to the positioning of the PID in a vertical, or up-and-down, plane.
• The vertical angulation differs depending on the radiographic technique being used: 
  • With the paralleling technique, the vertical angulation of the central ray is directed perpendicular to the film and the long axis of the tooth. 
  • With the bisecting technique, the vertical angulation is determined by the imaginary bisector; the central ray is directed perpendicular to the imaginary bisector. 

Vertical angulation of the PID refers to PID placement in an up-and-down (head-to-toe) direction. 

Correct Vertical Angulation 

• Correct vertical angulation results in a radiographic image that is the same length as the tooth. 
• Incorrect vertical angulation results in an image that is not the same length as the tooth being radiographed. 
• The image appears longer or shorter: 
  • Elongated 
  • Foreshortened  

A, If the vertical angulation is to too steep, the image on the film is shorter than the actual tooth. B, Foreshortened images. (From Iannucci J, Jansen Howerton L: Dental radiography: principles and techniques, ed 3, St Louis, 2006, Saunders.)

A, If the vertical angulation is to too flat, the image on the film is longer than the actual tooth. B, Elongated images. (From Iannucci J, Jansen Howerton L: Dental radiography: principles and techniques, ed 3, St Louis, 2006, Saunders.)

A

B

Things to remember:

BAIs include a metal indicator arm, plastic bite-blocks, and plastic aiming rings. The Eezee-Grip is the easiest to use with experience, and it is more comfortable for patient. The Stabe Bite-Block is  disposable.

PID Angulations – During the learning stages of this technique, BAIs will be used.

Retakes are necessary if there are overlapped contact areas.

The x-ray beam is directed perpendicular to the film. The open end of the PID is aligned parallel to the film.

Measurement of vertical angulation is marked on the outside of the tubehead.

When the open end of the PID is pointing downward, the PID has positive angulation. When the open end of the PID is pointing upward, the PID has negative angulation.

Foreshortening occurs when vertical angulation is excessive.

Elongation occurs when vertical angulation is insufficient .