1. Extra oral Radiology
Islam Kassem
ikassem@dr.com

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3. Skull Radiography
• Lateral cephalometric projection
• Posteroanterior projection
• Water’s projection
• Submentovertex projection
• Reverse Towne’s projection

4. Main indications
• Fractures of the maxillofacial skeleton
• Fractures of the skull
• Investigation of the antra
• Diseases affecting the skull base and vault
• TMJ disorders.
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7. Main maxillofacial/skull projections
Standard occipitomental (0° OM)
• 30° occipitomental (30° OM)
• Postero-anterior of the skull (PA skull) sometimes
referred to as occipitofrontal (OF)
• Postero-anterior of the jaws (PA jaws)
• Reverse Towne's
• Rotated postero-anterior (rotated PA)
• True lateral skull
• Submento-vertex (SMV)
• Transcranial
• Transpharyngeal.
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8. Standard occipitomental (0° OM)
• This projection shows
the facial skeleton and
• maxillary antra., and
avoids superimposition
of the
• dense bones of the
base of the skull.
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9. The main clinical indications include:
Investigation of the maxillary antra
Detecting the following middle third facial
fractures:
— LeFortI
— Le Fort II
— Le Fort III
— Zygomatic complex
— Naso-ethmoidal complex
— Orbital blow-out
Coronoid process fractures
• Investigation of the frontal and ethmoidal
sinuses
• Investigation of the sphenoidal sinus
(projection needs to be taken with the patient's
mouth open).
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10. Technique and positioning
1. The patient is positioned facing the film with
the head tipped back so the radiographic baseline
is at 45° to the film, the so-called nose-chin position.
This positioning drops the dense bones of the base
of the skull downwards and raises the facial bones
so they can be seen.
2. The X-ray tube head is positioned with the
central ray horizontal (0°) centered through the
occiput
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13. 30° occipitomental (30° OM)
• This projection also
shows the facial
skeleton, but
• from a different angle
from the 0° OM,
enabling
• certain bony
displacements to be
detected.
ikassem@dr.com

14. Main indications
• Detecting the following middle third facial
fractures:
— LeFortI
— Le Fort II
— Le Fort III
• Coronoid process fractures.
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15. Technique and positioning
1. The patient is in exactly the same position as
for the 0° OM, i.e. the head tipped back,
radiographic baseline at 45° to the film, in the nose-
chin position.
2. The X-ray tube head is aimed downwards
from above the head, with the central ray at 30° to
the horizontal, centered through the lower border
of the orbit
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18. Postero-anterior of the skull (PA skull)
This projection shows the
skull vault, primarily
the frontal bones and the
jaws.
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19. Main indications
• Fractures of the skull vault
• Investigation of the frontal sinuses
• Conditions affecting the cranium, particularly:
— Paget's disease
— multiple myeloma
— hyperparathyroidism
• Intracranial calcification.
ikassem@dr.com

20. Technique and positioning
1. The patient is positioned facing the film with the
head tipped forwards so that the forehead and tip
of the nose touch the film — the so-called forehead-
nose position. The radiographic baseline is
horizontal and at right angles to the film. This
positioning levels off the base of the skull and
allows the vault of the skull to be seen without
superimposition.
2. The X-ray tube head is positioned with the
central ray horizontal (0°) centered through the
occiput .
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24. Postero-anterior of the jaws (PA
jaws/PA mandible)
• This projection shows the
posterior parts of the
• mandible. It is not
suitable for showing the
facial
• skeleton because of
superimposition of the
base of
• the skull and the nasal
bones.
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25. Main indications
• Fractures of the mandible involving the
following sites:
— Posterior third of the body
— Angles
— Rami
— Low condylar necks
• Lesions such as cysts or tumors in the
posterior third of the body or rami to note any
medio-lateral expansion
• Mandibular hypoplasia or hyperplasia
• Maxillofacial deformities.
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26. Technique and positioning
1. The patient is in exactly the same position as
for the PA skull, i.e. the head tipped forward, the
radiographic baseline horizontal and perpendicular
to the film in the forehead-nose position.
2. The X-ray tube head is again horizontal (0°),
but now the central ray is centered through the
cervical spine at the level of the rami of the
mandible.
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29. Reverse Towne's
This projection shows the
condylar heads and necks.
The original Towne's view
(an AP projection) was
designed to show the
occipital region, but also
showed the condyles.
However, since all skull
views used in dentistry are
taken conventionally
in the PA direction, the
reverse Towne's (a PA
projection) is used.
ikassem@dr.com

30. Main indications
• High fractures of the condylar necks
• Intra capsular fractures of the TMJ
• Investigation of the quality of the articular
surfaces of the condylar heads in TMJ disorders
• Condylar hypoplasia or hyperplasia.
ikassem@dr.com

31. Technique and positioning
1. The patient is in the PA position, i.e. the
head tipped forwards in the forehead-nose position,
but in addition the mouth is open. The radiographic
baseline is horizontal and at right angles
to the film. Opening the mouth takes the condylar
heads out of the glenoid fossae so they can be
seen.
2. The X-ray tube head is aimed upwards from
below the occiput, with the central ray at 30° to
the horizontal, centered through the condyles.
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34. True lateral skull
This projection shows the skull
vault and facial skeleton from
the lateral aspect. The main
difference between the true
lateral skull and the true
cephalometric lateral skull
taken on the cephalostat is
that the true lateral skull is not
standardized
or reproducible. This view is
used when a single lateral view
of the skull is required but not
in orthodontics or growth
studies.
ikassem@dr.com

35. Main indications
• Fractures of the cranium and the cranial base
• Middle third facial fractures, to show possible downward
and backward displacement of the maxillae
• Investigation of the frontal, sphenoidal and maxillary sinuses
• Conditions affecting the skull vault,
particularly:
— Paget's disease
— multiple myeloma
— hyperparathyroidism
• Conditions affecting the sella turcica, such as:
— tumor of the pituitary gland in acromegaly.
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37. Technique and positioning
1. The patient is positioned with the head
turned through 90°, so the side of the face touches
the film. In this position, the sagittal plane of the
head is parallel to the film.
2. The X-ray tube head is positioned with the
central ray horizontal (0°) and perpendicular to
the sagittal plane and the film, centered through
the external auditory meatus .
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40. Submento-vertex (SMV)
• This projection shows
the base of the skull,
sphenoidal
• sinuses and facial
skeleton from below.
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41. Main indications
• Destructive/expansive lesions affecting the
palate, pterygoid region or base of skull
• Investigation of the sphenoidal sinus
• Assessment of the thickness (medio-lateral) of
the posterior part of the mandible before
osteotomy
• Fracture of the Zygomatic arches — to show
these thin bones the SMV is taken with
reduced exposure factors.
ikassem@dr.com

42. Technique and positioning
1. The patient is positioned facing away from the film. The head is
tipped backwards as far as is possible, so the vertex of the skull
touches the film. In this position, the radiographic baseline, is
vertical and parallel to the film.
2. The X-ray tube head is aimed upwards from below the chin, with the
central ray at 5° to the horizontal, centered on an imaginary line
joining
the lower first molars .
Note: The head positioning required for this projection
means it is contraindicated in patients
with suspected neck injuries, especially suspected
fracture of the odontoid peg.
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46. Water’s view
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52. Temporomandibular Joint Radiography
Radiographs of the temporomandibular joint
(TMJ) can be very difficult to examine because
of the multiple adjacent bony structures.
The articular disc and other soft tissues of the
TMJ cannot be examined by radiographs.
Special imaging techniques (e.g., arthrography,
magnetic resonance imaging) must be used.
Radiographic projections of the TMJ can be used
to show the bone and the relationship of the
jaw joint.

54. Thank you
• You can get the lecture on
• http://www.slideshare.net/islamkassem
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