This document compares and contrasts the parallel angle technique and bisecting angle technique for periapical radiographs. The parallel angle technique positions the film parallel to the tooth's long axis with the x-ray beam directed perpendicularly, allowing for reproducible images. However, it can be uncomfortable and difficult to position. The bisecting angle technique aims the beam at 90 degrees to an imaginary line bisecting the tooth's angle to the film, making positioning easier but resulting in more variable images. Both techniques have advantages and disadvantages related to reproducibility, positioning, and distortion.

2. PERI-APICAL RADIOGRAPHS
VS
Bisecting Angle Technique
Parallel Angle Technique
SALMAN ZAHID
DEPARTMENT OF OPERATIVE DENTISTRY
SUPERVISED BY DR. SADAF ALI

3. Peri-apical radiograph:
Intraoral techniques designed to show individual teeth
and the tissues around the apices.

4. Peri-apical radiograph Indications:

5. Caries detection

6. Pulp chamber & canal
Anatomy of pulp chamber
and canal is highly variable
Pulp Stones

7. Canal length determination

8. Secondary caries detection

9. Status of Root Filling

10. Follow up

11. Trauma

12. Peri-apical pathology
12

13. Root resorption

14. Bone loss
 Alveolar bone height
 Alveolar bone health
 Generalised vs localised
alveolar bone loss

15. Basically two techniques for
peri-apical radiographs have
been developed
 1- Parallel angle technique
 2- Bisecting angle technique

16. Paralleling technique
 In this technique film is positioned parallel to the
long axis of the tooth under investigation and
beam is directed perpendicularly

18. Film
Central axis of tooth

19. Film
Central axis of tooth
Central rays of x-ray beam

20. Bisectingangle technique
 Based on principal of aiming x-ray beam at 90 degrees to
an imaginary line which bisects the angle between the
longitudinal axis of the tooth and the film

24. comparISON OF advantages of the two techniques
1. Vertical and horizontal
angulation automatically
determined
2. Reproducible
radiographs when placed
in holder
3. Relative position of
film, teeth and x-ray
beam are always
maintained
Paralleling technique Bisecting technique
1. Positioning of the film is
comfortable
2. simple and quick
3. same length of tooth formed
on radiograph

25. comparISON OF advantages of the two techniques
1. Vertical and horizontal
angulation automatically
determined
2. Reproducible
radiographs when placed
in holder
3. Relative position of
film, teeth and x-ray
beam are always
maintained
Paralleling technique Bisecting technique
1. Positioning of the film is
comfortable
2. simple and quick
3. same length of tooth formed
on radiograph

26. comparISON OF advantages of the two techniques
1. Vertical and horizontal
angulation automatically
determined
2. Reproducible
radiographs when placed
in holder
3. Relative position of
film, teeth and x-ray
beam are always
maintained
Paralleling technique Bisecting technique
1. Positioning of the film is
comfortable
2. simple and quick
3. same length of tooth formed
on radiograph

27. comparISON OF disadvantages of the two techniques
Paralleling technique
1. Positioning of image receptor
can be very uncomfortable and
causes gagging
2. Positioning film holder with in
the mouth is difficult
3. Anatomy of mouth makes
technique impossible e.g curved
palate
4. Technique can not performed
satisfactorily using a short focal
distance because of resultant
magnification
Bisecting technique
1. Involvement of variable
causes distortion of image
2. Zygomatic buttress frequently
overlies the root of molar
3. Non reproducible views
4. Coning off or cone cutting
may result if beam not aimed at
center
5. Incorrect horizontal
angulation cause overlapping

28. comparISON OF disadvantages of the two techniques
Paralleling technique
1. Positioning of image receptor
can be very uncomfortable and
causes gagging
2. Positioning film holder with in
the mouth is difficult
3. Anatomy of mouth makes
technique impossible e.g curved
palate
4. Technique can not performed
satisfactorily using a short focal
distance because of resultant
magnification
Bisecting technique
1. Involvement of variable
causes distortion of image
2. Zygomatic buttress frequently
overlies the root of molar
3. Non reproducible views
4. Coning off or cone cutting
may result if beam not aimed at
center
5. Incorrect horizontal
angulation cause overlapping

29. comparISON OF disadvantages of the two techniques
Paralleling technique
1. Positioning of image receptor
can be very uncomfortable and
causes gagging
2. Positioning film holder with in
the mouth is difficult
3. Anatomy of mouth makes
technique impossible e.g curved
palate
4. Technique can not performed
satisfactorily using a short focal
distance because of resultant
magnification
Bisecting technique
1. Involvement of variable
causes distortion of image
2. Zygomatic buttress frequently
overlies the root of molar
3. Non reproducible views
4. Coning off or cone cutting
may result if beam not aimed at
center
5. Incorrect horizontal
angulation cause overlapping

30. REFERENCES:
 ESSENTIAL OF RADIOGRAPHY AND RADIOLOGY BY
ERIC WHAITES
 IMAGES FROM INTERNET