Thorough knowledge of the indications of various extra oral techniques allows accurate and timely diagnosis of various maxillofacial pathologies. Further, we can arrive at a diagnosis with minimum number of x-rays there by reducing patient exposure to radiation.

2. Radiographs
(Part 2)
Presented by
Dr. Neha Sharma
PG II YR

3. CONTENTS
3
 PANORAMIC IMAGING
 EXTRAORAL RADIOGRAPHS
CEPHALOMETRIC LANDMARKS
LATERAL SKULL PROJECTION
SUBMENTOVERTEX PROJECTION
PA WATERS PROJECTION
REVERSE TOWNES PROJECTION
TMJ IMAGING
 CONCLUSION

4. HISTORY OF -
EXTRAORAL RADIOGRAPHIC TECHNIQUES

5. EXTRA-ORAL SOURCE
Discovered by
Dr. Hisatugu Numata of
Japan, 1933

6. Father of Panoramic Radiography
•1949, extra-oral films
•X-ray source - stationary
Dr Yrjo Veli Paatero

7. What is panoramic imaging
/pantomography???
A technique for producing a single tomographic
image of the facial structures that includes both
the maxillary and mandibular dental arches and
their supporting structures.

8. ‘Panorama’ ‘Tomography’
An
unobstructed
view of a
region in
every
direction
An X-ray technique
for making
radiographs of
layers of tissue in
depth without the
interference of
tissues above and
below the level
PANTOMOGRAPHY

9. Equipment
1. Panoramic X-ray unit

10. 2. Screen film

11. 3. Intensifying screens

12. 4.
Cassette

14. BONY LANDMARKS IN MANDIBLE
14
1
1. Condylar head 2. Sigmoid notch 3. Coronoid process 4. External oblique ridge
5. Mandibular canal
2
3
4
5
6. Post. Border of Ramus 8. Lower border7. Gonial Angle
6
7
9. Mental ridge 11. Mental foramen10. Genial tubercle
13. Lingula
12. External Oblique Ridge
14. Hyoid bone
8
9
10
11
12
13

15. BONY LANDMARKS IN MAXILLA
15
15
15. Glenoid fossa
19. Floor of Max.Sinus
17. Zygomatic Arch16. Articular eminence 18.Post. wall max. sinus
20. Zygomatic process of max. forming innominate line
21. Hard palate 22. Floor of the orbit 23. Nasal septum 24. Incisive foramen
25. Inferior choncha 26. Meatus 27. Frontal process of Z.bone
16
17
18
19
20
21
22
23
29
25
24
26
28.Pterygo max. fissure
30. Maxillary tuberosity29.Spine of the sphenoid bone 31. Lateral pterygoid plate
31
30
28
27

16. OTHER STRUCTURES
16
32
32. External acoustic meatus 34. Shadow of ear lobe33. Styloid process
35. nose 36. Shadow of Cervical spine
33
34
35
36 37
37. Cervical vertebrae
38
38. Nasopharyngeal space 39. Shadow of uvula
40
39
40 Submandibular fossa

17. A panoramic film is not
as useful as periapical
radiography for
detecting small carious
lesions, periodontal
diseases, or periapical
lesions.
It should not be used as a
substitute for intraoral
films.

18. Impacted teeth and its relation with the mandibular
canal.

19. To evaluate eruption patterns

20. To detect diseases, lesions, conditions of the jaws
and the extent of large lesions.

21. to evaluate trauma

22. Retainedteethor root tips in edentulous patients

23. Post-operative examination and patient education.

24. Implants

25. ROTATION
CENTER
The pivotal point or axis,
around which the cassette
carrier and X-ray
tubehead rotate, is
termed a ROTATION
CENTER.

26. Double center of rotation

27. Three stationary centers of rotation

28. Continously moving center of rotation

30. During the exposure cycle, the machine shiftsto one or
more additional rotation centers.
This rotational change allowsthe image layer to
conformto the shape of the dental arches.
The location and no. of rotational centers influence the
size and shape of the focal trough.

31. Focal
trough
The focal trough (also
known as the Image layer)
is defined as a 3-D
curved zone in which
structures are clearly
demonstrated on a
panoramic radiograph.

32. Advantages
1. Fieldsize
2. Minimal exposure
3. Simplicity
4. Patient cooperation
5. Useful in patients with trismus & gagging
6. Valuable visual aid for patient education

33. Disadvantages
1. Cannot be usedin detection of caries and periodontal disease.
2. Overlapping of teethin premolar region
3. Focal trough limitations
4. Shadowof cervical spine in the lower anterior region.
5. Ghost images
6. Equipment cost

34. 34
COMMON ERRORS

35. PATIENT POSITIONING ERRORS

36. Positioning of lips and tongue

37. Positioning of Frankfort plane
upward

38. Positioning of Frankfort plane
downward

39. Positioning of teeth anterior to
focal trough

40. Positioning of teeth posterior to
focal trough

41. Positioning of midsagittal plane

42. Patient movement

43. Positioning of spine

44. Processing Errors
Underexposed, light, washed out
image
Very dark film, Overexposed
Film Fog
Improper filter in daylight loader

45. Panoramic Image=
Right lateral
image+
PA image+
Left Lateral image

46. EXTRAORA
L
RADIOGRA
PHIC
TECHNIQUE
S
7/29/2014 46

47. LATERAL CEPHALOMETRIC
PROJECTION
Film position - cassette is
placed perpendicular to the floor
with long axis of the cassette
placed vertically.
Position of patient - left side
of the face is positioned against
the cassette. Mid sagittal plane is
perpendicular to the floor and
parallel to film.
Central ray - perpendicular to
the film.

48. Exposure parameters
KVp= 84
mAs= 13
Seconds =1.6

49. INDICATIONS
• To evaluate facial growth and
development, trauma, disease and
developmental anomalies.
• Demonstrates the bones of the face,
skull as well as the soft tissue profile
of the face.

50.  Film position - cassette is
perpendicular to the floor with long
axis of the cassette placed vertically.
 Position of patient –The film is
adjusted so that the upper
circumference of the skull is .5 inch
below the lower border of the cassette.
 Central ray - perpendicular to the film
towards the E.A.M.
TRUE LATERAL SKULL

51. LATERAL SKULL PROJECTION
51
Exposure parameters
KVp= 65 mAs= 10 Seconds =.5-2 sec

52. To survey skull and facial bone for trauma or pathology.
Nasopharangeal soft tissue, paranasal sinus and hard
palate.
Condition affecting sella turcica, such as tumour of pitutary
gland in acromegaly.
Indications

53. 7/29/2014 53
PA WATERS PROJECTION
Film position - cassette is
perpendicular to the floor with
long axis of the cassette placed
vertically.
Position of patient - mid
sagittal plane perpendicular to the
floor and parallel to film.
Head is extended so that only the
chin touches the casette.
The tip of nose is .5 to 1.5 cm
away from the cassette
Central ray- perpendicular
and to the midpoint of the film.

54. 54
Exposure parameters
• KVp= 65
• mAs= 10
• Seconds =2-3 sec

55. INDICATIONS
55
• Demonstrate the maxillary , frontal and ethmoidal
sinuses.
• The orbit, frontozygomatic suture, nasal cavity,
coronoid process of the mandible and the zygomatic
arch are also seen.

56. 56
Film position- cassette is placed
perpendicular to the floor with long
axis of the cassette placed
horizontally.
Position of patient- head is
centered on the cassette (Head and
neck tipped back).Vertex of the skull
touches the cassette.
Central raY- perpendicular to the
film. It enters via between angle of
mandible and in a coronal plane ¾
inches anterior to the external
auditory meatus.
SUBMENTOVERTEX (BASE)
PROJECTION

57. SUBMENTOVERTEX (BASE) PROJECTION
57
Exposure parameters
KVp= 50
mAs= 20
Seconds =.4

58. INDICATIONS
58
 Help to study destructive lesion affecting
the palate, pterygoid region or base of the
skull, sphenoidal sinus.
 Fractures of zygomatic arches (JUG
HANDLE).

59. LATERAL OBLIQUE
Film position - flat against the
patient cheeks and is centered over
the body of the mandible.
Position of patient - ala tragus line
is parallel to the floor. Inferior border
of the cassette should be parallel to
the lower border of the mandible and
below it.
Central ray - directed 2cm behind
the angle of the mandible and beam
is directed -10° to -15°

60. Exposure parameters
KVp= 65-70 mAs= 10 Seconds =.8

61. Lateral Oblique Views - Largely
replaced by panoramic views
Indications:
• Impacted third molars
• fractures of the ramus, condyle or body of
the mandible.
61

62. 62

63. TRANSCRANIAL VIEW
63
Film position - cassette is
placed flat against the patient ear
and centred over the TMJ of
interest.
Position of patient - head is
adjusted so that the saggital plane
is vertical.
The ala tragus is parallel to floor.
Central ray - is ½ inch behind
and 2 inch above the auditory
meatus

64. 64
Exposure parameters
KVp= 70
mAs= .7
Seconds =1.5
Indications
• Arthritic changes on the articular surface.
• To evaluate the joint’s bony relationship.

65. TRANSPHARYNGEAL VIEW
65
Film position - cassette is placed
flat against the patient ear and is
centered to a point ½’” anterior to
ext. auditory meatus, over the TMJ
of interest.
Position of patient - head is
adjusted so that the saggital plane is
vertical.The ala tragus is parallel to
floor.
Central ray - from the opposite
side cranially at an angle -5° to -10°.

66. INDICATIONS
66
• Fracture of condylar head and neck of the mandible
Exposure
parameters
KVp= 70
mAs= 7
Seconds =1.5

67. VIEW
67
Film position - cassette is placed
behind the patient’s head at an angle
of 45° to the saggital plane.
Position of patient - head is
adjusted so that the saggital plane is
vertical. The canthomeatal line is
parallel to floor. The mouth should be
wide open.
Central ray - from the opposite side
cranially at an angle -5° to -10°.

68. INDICATIONS
68
 The anterior view of the temporomandibular joint
 Medial displacement of fractured condyle
 Fracture of neck of condyle.
 There is minimum superimposition.
Exposure
parameters
KVp= 70
mAs= 7
Seconds =.8

69. REVERSE-TOWNE PROJECTION(OPEN
MOUTH)
69
Film position - cassette is
placed perpendicular to the floor
with long axis of the cassette
placed horizontally.
Position of patient-
Pt. forehead and tip of the nose
should touch the film and is
asked to keep his mouth wide
open
Central ray- directed via mid
saggital plane at the level of the
mandible and is perpendicular
to the film.

70. 70
Exposure
parameters
KVp = 65
mAs = 10
Seconds = 2-3
INDICATIONS:
• Suspected fracture of the condylar neck.
• Intracapsular fracture of the TMJ
• Shows posterolateral wall of maxillary sinus

71. DRAWBACKS OF EXTRA ORAL
TECHNIQUES
71
 Magnification occurs due to the greater object
to film distance used.
 Details are not well defined.
 Contrast is reduced as the secondary
radiation produced by the soft tissues is
more.
 It is a 2- D image of 3- D structure.

72. CONCLUSION
Thorough knowledge of the indications of
various extra oral techniques allows accurate
and timely diagnosis of various maxillofacial
pathologies. Further, we can arrive at a
diagnosis with minimum number of x-rays
there by reducing patient exposure to
radiation.

73. • White SC, Pharoah MJ.Oral Radiology
Principles And Interpretations.6thelsevier::
Missouri; 2009
• Mac Donald,Avery.Dentistry For The Child
And Adolscent.9th.elsevier: Missouri; 2011
• Langland and Langlais.. Principles Of Dental
Imaging.7thed.elsevier: Muir; 2005
• Freny R,Karjodkar.Textbook Of Dental And
Maxillofacial Radiology.6thed.elsevier: Reed;
2000
• Dental radiography, Principles and
Techniques; Haring, Howerton;Third
edition.

74. DR ANKIT GOEL, SUBHARTI.