Review: Bisecting Technique

Author: Boban Fidanoski

1. The principle which states that two triangles are equal if they have two equal angles and they share a common side is called: rule of isometry
   
   
2. In geometry the side of a right triangle opposite the right angle is called: hypotenuse
   
   
3. Where is the film placed in relation to the tooth when performing bisecting angle radiography?
   Along the lingual surface of the tooth
   
   
4. List two ways to stabilize the film during bisecting angle radiography?
   - Film holder
   - Finger holding method
   
   
5. List reasons why the digital method of film stabilization is least desirable?
   1. Unnecessary radiation of patient’s/client’s hand
   2. Patient/client may use excessive force to stabilize the film, causing it to bend and distort the image
   3. Patient/client may allow film to slip from its original position, resulting in inadequate exposure of the area
   4. Dental radiographer may align PID incorrectly, due to a lack of a film holder, causing partial image or cone-cut
   
   
6. How is the vertical angulation different when using the bisecting angle technique compared with paralleling technique?
   With paralleling technique, vertical angulation is directed perpendicular to the film, whereas with bisecting technique, vertical angulation is directed perpendicular to the imaginary bisector.
   
   
7. Describe the proper direction of the central ray in the bisecting technique?
   - Vertical angulation of the central beam is directed perpendicular to the imaginary bisector
   - Horizontal angulation is directed through the contact areas between the teeth
   - X-ray beam has to be centered directly towards the film, to avoid cone-cut
   
   
8. Describe the distance between the film and tooth in the bisecting technique?
   - Film must be placed against the lingual surfaces of the tooth
   - Occlusal end of the film must extend 1/8 of an inch beyond incisal edge or occlusal surfaces
   - The apical end must rest against the palatal or alveolar tissues
   
   
9. What is the result when using excessive vertical angulation with bisecting angle radiography?
   Foreshortening of the image results from excessive vertical angulation.
   
   
10. What is the result when using insufficient vertical angulation with bisecting angle radiography?
    Elongation of the image results from insufficient vertical angulation
    
    
11. Describe the film placement for bisecting angle radiography with anterior teeth?
    Seven X-ray images are required for anterior section of the teeth, 4 for maxillary and 3 for mandibular teeth. Film with size No.1 is used. Procedure has to begin from maxillary left side to maxillary right side, then down to mandibular right side and finish with mandibular left side. Sequence for film placement:
    1. Maxillary left canine
    2. Maxillary left central and lateral incisor
    3. Maxillary right central and lateral incisor
    4. Maxillary right canine
    5. Mandibular right canine
    6. Mandibular incisors
    7. Mandibular left canine
    
    
12. List five guidelines for film placement when using bisecting angle technique?
    1. White side of the film always faces the teeth
    2. Anterior films are always placed vertically
    3. Posterior films are always placed horizontally
    4. Incisal or occlusal edge of the film has to be 1/8 of an inch extended beyond incisal edge or   occlusal surfaces of the teeth.
    
    
13. What is the major advantage of using bisecting angle radiography?
    It can be used without film holder when the anatomy of the patient precludes the use of a film-holding device
    
    
14. What are some disadvantages of using bisecting angle radiography?
    1. Image distortion
    2. Angulation problems
    3. Unnecessary exposure
    
    
15. What is the position of the identification dot when bisecting angle radiography?
    Towards the incisal edge or occlusal surfaces of the tooth.
    
    
16. Which size film is used most often when performing bisecting angle radiography on an adult?
    For anteriors, film No.1, for posteriors film No.2
    
    
17. What is the direction of the central ray when using bisecting angle technique?
    Central ray has to be positioned centrally to the examined area so the film is positioned in the middle of the central ray. Central ray has to be parallel to the imaginary bisector.
    
    
18. Which technique is preferred for exposure of periapical films?
    The paralleling technique is preferred to the bisecting technique for exposure of periapical films and should be used whenever possible.

© February, 2007 Copyright - Text
by B.Fidanoski- Port Credit, ON - Canada