OMRD extraoral radiography-final (1).pptx

 Introduction
 Extraoral radiographic techniques
Radiography of the Skull
Lateral Cephalogram
True Lateral
PA Skull
PA Cephalogram
Towne’s Projection
Submentovertex view (base of the skull)
CONTENTS

Radiography of Paranasal sinuses
• Caldwell view
• Granger’s view
Radiography of Maxillary sinus
 Standard Occipitomental projection
 Modified Method (30 degree Occipitomental Projection)
 Bregma Menton
 PA Water’s

Radiography of the Mandible
 PA Mandible
 Rotated PA mandible
 Lateral oblique views
 Body
 Ramus
Radiography of Temporomandibular Joint
 Transcranial Projection
 Transpharyngeal Projection
 Transorbital Projection
 Reverse Towne’s Projection

Radiography of Zygomatic Arches
 Jughandle View (A modification of Submentovertex View)

 In Extraoral radiography both the X-ray source and image receptor
are placed outside the patient’s mouth.
 Extraoral radiographs do not show the details as good as intraoral
films.
 Extraoral radiographs are very useful for evaluating large areas of
the skull and jaws but are not adequate for detection of subtle
changes such as the early stages of dental caries or periodontal
disease.
 There are many type of Extraoral radiographs. Some types are
used to view the entire skull, whereas other types focus on the
maxilla and mandible.
INTRODUCTION

 When it is not possible to place the film intraorally as during
trismus.
 To examine the extent of large lesions.
 When jaws and other facial bones have to be examined for
evidence of disease lesions and other pathological conditions.
 To evaluate skeletal growth and development.
 To evaluate fractures of the maxillofacial skeleton.
 Investigation of the antra.
 To evaluate TMJ disorders.
Indications of Extraoral Radiography

 Magnification occurs due to greater object to film
distance.
 Details are not well-defined due to the use of
intensifying screens.
 Contrast is reduced as the secondary radiation is
produced by the soft tissues is more.
Drawbacks

 Extraoral radiographs are produced with
◦ Conventional dental X-ray machines
◦ Panoramic machines
◦ Higher capacity medical X-ray units.
Film focus distance used for all the skull radiography is 100
cms/40 inches except for cephalometry that has 150 cms/60
inches.
X-ray unit

 They make use of intensifying screens with
screen films.
Image receptors

Canthomeatal line
Reference planes

 Patient should be explained about the radiographic procedure
prior to the exposure.
 Lead apron should be placed on to the patient. A thyroid collar
is not recommended as it blocks part of beam and obscures
important diagnostic information.
 All the metallic objects in head and neck region such as
earrings, necklaces, hearing aids, hairpins, eyeglasses,
complete or partial removable dentures etc should be removed
from the patient.
Patient preparation

 It is a technique for producing a single tomographic
image of facial structures that includes both maxillary
and mandibular arches and their supporting
structures.
 This is curvilinear variant of conventional tomography
and is also used on the principle of the reciprocal
movement of an x-ray source and an image receptor
around a central point or plane called the image layer
in which the object of interest is located.

1) As a substitute for full mouth intraoral periapical radiographs.
2) For evaluation of tooth development for children, the mixed dentition and
also the aged.
3) To assist and assess the patient for and during orthodontic treatment.
4) To establish the site and size of lesions such as cysts, tumors and
developmental anomalies in the body and rami of the mandible.
5) Prior to any surgical procedures such as extraction of impacted teeth,
enucleation of a cyst, etc.
6) For detection of fractures of the middle third face and the mandible after
facial trauma.
INDICATIONS

7) For follow-up of treatment, progress of pathology of postoperative bony
healing.
8) Investigation of TM joint dysfunction.
9) To study the antrum, especially to study the floor, posterior and anterior
walls of the antrum.
10) Periodontal disease-as an overall view of the alveolar bone levels.
11) Assessment for underlying bone disease before constructing complete
or partial dentures.
12) Evaluation of developmental anomalies.
13) Evaluation of the vertical height of the alveolar bone before inserting
osseointegrated implants.

Lateral Cephalometric
Projection

 It is the most commonly used projection in dentistry.
 It is a standardized and reproducible form of skull
radiography.
 It is made with a cephalostat that helps maintain a
constant relationship among the skull, the film, and
the X-ray beam.
 The focal spot to film distance (150 cms/60 inches)
is maintained all throughout.

 The image receptor is positioned
parallel to the patient’s midsagittal
plane.The site of interest is placed
toward the image receptor to
minimize distortion.
 In cephalometric radiography, a
wedge filter at the tube head is
positioned over the anterior aspect
of the beam to absorb some of the
radiation and to allow visualization
of soft tissues of the face.
 The central ray is directed
perpendicular to the cassette
through the external auditory
meatus.
Technique

1 Parietal bone
2 Diploic canal
3 Coronal suture
4 Groove for the medial meningeal
artery
5 Lambdoid suture
6 Pineal body, with calcifications
7 Internal occipital protuberance
8 External occipital protuberance
9 Occipital squama
10 Internal occipital crest
11 Mastoid sinuses
12 Petrous part of the temporal bone
(petrosal
bone)
13 Occipital condyle
14 External auditory meatus
15 Internal auditory meatus
16 Atlas
17 Anterior tubercle of atlas
18 Dentoid process of axis
19 Styloid process
20 Temporomandibular joint
21 Clivus and basilar portion
22 Dorsum sellae, posterior clinoid
process
23 Sella turcica
24 Anterior clinoid process
25 Sphenoidal sinus
26 Floor of the medial cranial fossa
27 Major and minor alae of the
sphenoid bone
28 Anterior cranial fossa
29 Frontal sinus
30 Crista galli with the cribriform
lamina

31 Nasal bone
32 Ethmoid labyrinth
33 Optic canal
34 Orbit
35a Frontal process of the zygomatic
bone(distant from radiation
source)
35b Frontal process of the zygomatic
bone (near radiation source)
36 Fossa of lacrimal sac
37a Zygomatic process of the
maxilla
37b As 37a (near plane of focus)
38 Zygomatic arch
39 Inferior nasal concha
40 Maxillary sinus (borders)
41 Pterygopalatine fossa
42 Pterygoid process with laminae
43 Hamulus, medial lamina of the
pterygoid process
44 Nasal cavity, floor
45 Bony palate
46 Anterior nasal spine
47 Posterior nasal spine
48 Coronoid process of the
mandible
49 Condylar process of the
mandible
50 Mandibular canal
51 Soft tissue shadow of the tongue
52 Radiolucency of the epipharynx
53a Compact bone of the mandible
(distant from radiation source)
53b As 53a (near radiation source)
54 Chin
55 Lateral nasal cartilage
56 Alar nasal cartila

 This projection demonstrates the bones of the face, skull as well as
the soft tissue profile of the face.
 Clinical indications can be considered under two major headings -
orthodontics and orthognathic surgery
Orthodontics
 Initial diagnosis - confirmation of the underlying skeletal and/or soft
tissue abnormalities
 Treatment planning
 Monitoring treatment progress, e.g. to assess anchorage
requirements and incisor inclination
Indications

 Appraisal of treatment results, e.g. 1 or 2 months before
the completion of active treatment to ensure that treatment
targets have been met and to allow planning of retention.
Orthognathic surgery
 Preoperative evaluation of skeletal and soft tissue patterns
 To assist in treatment planning
 Postoperative appraisal of the results of surgery and long-
term follow-up studies.

 The image receptor is positioned
parallel to the patient’s midsagittal
plane.The site of interest is placed
toward the image receptor to minimize
distortion.
 The film is adjusted so that the upper
circumference of the skull is half inch
below the upper border of the
cassette.
perpendicular to the cassette and the
midsagittal plane and towards the
external auditory meatus.
Technique

 Fractures of the cranium and the cranial base
 Middle third facial fractures, to show possible downward and
backward displacement of the maxilla
 Investigation of the frontal, sphenoidal and maxillary sinuses
 Conditions affecting the skull vault,
◦ Paget’s disease
◦ Multiple myeloma
◦ Hyperparathyroidism
 Conditions affecting the sella turcica,
◦ Tumor of pituitary gland in acromegaly
INDICATIONS

 The image receptor is placed in
front of the patient,
perpendicular to the mid
sagittal plane and parallel to
coronal plane, so that the
canthomeatal line is
perpendicular to the image
receptor.
 Central Ray is directed at right
angles to the film through the
midsagittal plane through the
occiput.
Technique
頭往前傾
平行地面

 Fractures of the skull vault and other facial bones
 Disease or developmental abnormality
 Investigation of the frontal sinuses
 Conditions affecting the cranium
◦ Paget’s disease
◦ Multiple myeloma
◦ Hyperparathyroidism
 Intracranial calcifications
Indications

 It is identical to PA view of the jaws except
that it is standardized and reproducible.
 The cassette is placed perpendicular to
the floor.
 The sagittal plane should be vertical and
perpendicular to the film.
 The head is tipped downwards so that
only the nose touches the film.The
canthomeatal line is at 100
with the film.
 Central Ray is directed at right angles to
the film through the midsagittal plane
through the occiput.
Technique
100

 It is used for assessment of facial asymmetries and
for preoperative and postoperative comparisons in
orthognathic surgeries involving the mandible.
Indications

 The cassette is placed perpendicular to
the floor.
 The long-axis of the cassette is
positioned vertically.
 This is an anteroposterior view, with the
back of the patient’s head touching the
film.The canthomeatal line is
 The central ray is directed at 30 degrees
to the canthomeatal line and passes
through it at a point between the
Technique

 It is primarily used to observe the occipital area
of the skull.
 The necks of the condyles can also be viewed.

Submentovertex
(base of the skull)

 The image receptor is positioned parallel to
patient’s transverse plane and
perpendicular to the midsagittal and coronal
planes.To achieve this, the patient's neck is
extended as far backward as possible, with
the canthomeatal line forming a 50
degree
angle with the receptor.
 The central beam is perpendicular to the
image receptor, directed from below the
mandible toward the vertex of the skull and
centered about 2 cms anterior to a line
connecting the right and left condyles.
 Exposure parameters
 50 kVp 20-30 mA 0.4 sec
Technique

1 Maxillary teeth
2 Mandibular teeth
3 Impacted tooth 48
4 Basal compact bone of
the mandible
5 Anterior nasal spine
6 Osseous nasal septum
7 Nasolacrimal canal
8 Nasal conchae with
ethmoid labyrinth
9 Palatal bone, dorsal
border
10 Maxillary sinus, borders
11 Nasal cavity, lateral wall
12 Infraorbital margin
13 Canine fossa
14 Sphenoidal sinus
15 Pterygoid process,
lateral lamina
16 Pterygoid process,
medial lamina
17 Posterior nasal spine
18 Zygomatic bone
19 Zygomatic arch
20 Temporal fossa

21 Coronoid (muscular)
process of the mandible
22 Lingula
23 Mandibular condyle
24 Angle of the mandible
25 Coronal suture
26 Foramen ovale
27 Spinous foramen
28 Middle lacerate foramen
29 Carotid canal
30 Dorsum sellae
31 Anterior tubercle of atlas
32 Transverse foramen of
atlas
33 Odontoid bone (dentoid
process of axis)
34 Great occipital foramen
(foramen magnum)
35 Occipital condyle
36 Mastoid sinuses
37 Occipital bone
38 Cervical vertebrae

 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.
Indications

 Same as that in
submentovertex.
 The exposure time for the
zygomatic arch is reduced
to approximately one-third
the normal exposure time
for a submentovertex
projection.
Jug handle view

 The film and the sagittal plane of the patient’s head are not
parallel.
 The X-ray beam is aimed perpendicular to the film but is
oblique to the sagittal plane of the patient.
 A variety of different oblique lateral projections is possible
with different head and X-ray beam positions.

 Assessment of the presence and/or position of unerupted
teeth
 Detection of fractures of the mandible.
 Evaluation of lesions or conditions affecting the jaws including
cysts, tumors, giant cell Lesions, and osteodystrophies.
 As an alternative when intraoral views are unobtainable
because of severe gagging or if the patient is unable to open
the mouth or is unconscious.
 As specific views of the salivary glands or TMJ
Main indications

 The image receptor is
placed against the patient's
cheek on the side of interest
and centered in the molar-
premolar area.
 The cassette is positioned
so that its lower border is
parallel with the inferior
border of the mandible but
lies at least 2 cm below it.
 The sagittal plane is tilted so
that it is 50
to the vertical
and the head is rotated 100
to 150
from the true lateral
position.
 The mandible is
extended as far as
possible.
 The centring position of
the tube is the
contralateral side of the
mandible at a point 2 cm
below the inferior
border in the region of
the first/second
permanent molar
Technique

 The cassette is placed flat
against the patient's cheek
and is centered over the
ramus of the mandible.
 The mandible is protruded
slightly to separate it from
the vertebral column.
 The inferior border of the
cassette should be parallel
to the lower border of the
mandible and below it.
 The sagittal plane is tilted so
that it is 100
to the vertical and
the head is rotated 50
from the
true lateral position.
from 2 cm below the angle of
the mandible opposite to the
side of interest, to a point
posterior to the third molar
region on the side opposite the
cassette.The beam is directed
upward -100
to -150
and
centered on the ramus of the
mandible.The beam must be
directed perpendicular to the
horizontal plane of the film.
Technique

 The cassette is placed in front of the
patient, so that the median sagittal plane
should be perpendicular to the cassette.
The head is then adjusted to bring the
orbito-meatal baseline perpendicular to
the cassette
 The cassette should be positioned such
that the middle of cassette, is centred at
the level of the angles of the mandible.
perpendicular to the cassette and
centred in the midline at the levels of the
angles of the mandible.
Technique

 Fractures of the mandible involving the following sites:
◦ Posterior third of the body
◦ Angles
◦ Rami
◦ Condylar necks
 Lesions such as cysts or tumours in the posterior third of the
body or rami to note any medio-lateral expansion
 Mandibular hypoplasia or hyperplasia
 Maxillofacial deformities.
Indications

 This projection shows the tissues of one side of
the face and is used to investigate the parotid
gland and the ramus of the mandible.

 The patient is positioned facing the film, with the occlusal plane
horizontal.
 The head is then rotated 100
to the side of interest.This positioning
rotates the bones of the back of the skull away from the side of the
face under investigation.
 The X-ray tubehead is positioned with the central ray horizontal
(00
), aimed down the side of the face.
Technique

 Stones/calculi in the parotid glands
 Lesions such as cysts or tumours in the ramus to note
any mediolateral expansion
 Submasseteric infection - to note new bone formation.
Indications

PROJECTIONS FOR
MAXILLARY
SINUS

Standard Occipitomental
projection (00
OM)

 This projection shows the facial skeleton and
maxillary antra, and avoids superimposition of
the dense bones of the base of the skull.

 The cassestte is placed perpendicular to the floor.
 The patient is positioned facing the film with the head tipped
back so that the canthomeatal line is at 450
to the film.
 The central ray is directed horizontally (00
) through the occiput
Technique
頭往上仰

 Investigation of the maxiliary antra.
 Detecting the following middle third facial fractures:
◦ Le Fort I
◦ Le Fort II
◦ Le Fort III
◦ Zygomatic complex
◦ Naso-ethmoidal complex
◦ Orbital blow-out
 Coronoid process fractures
 Investigation of the frontal and ethmoidal sinuses
Indications

 The patient is in exactly the same position as for the 00
OM,
i.e. the head tipped back, radiographic baseline at 450
to the
film.
 The X-ray tube head is aimed downwards from above the
head, with the central ray at 300
to the horizontal, centered
through the lower border of the orbit
Technique
頭往上仰

◦ Le Fort I
◦ Le Fort II
◦ Le Fort III
 Coronoid process fractures.
 Note: Ideally for fracture diagnosis two views at right
angles are required but the 00
OM and 300
OM provide
two views of the facial bones at two different angles
therefore in cases of suspected facial fracture both views
are needed.
Indications

 This projection is primarily used to demonstrate the
walls of the maxillary sinus (especially in the
posterior areas), the orbits, the zygomatic arches
and the nasal septum.
 It also demonstrates medial or lateral deviations of
any part of the mandible.

 The cassette is placed parallel to the
floor.
 The midsagittal plane should be vertical
and perpendicular to the plane of the
film.
 The patient's chin is extended as far as
comfortable, to make the lower border of
the mandible as parallel to the cassette
as possible.
 Only the chin touches the cassette.
 The canthomeatal line should also be
approximately parallel to the plane of
the film.
Technique

PA Water’s view
(Parietoacanthial
Projection)

front of the patient and
perpendicular to the midsagittal
plane.
 The patient's head is tilted
upward so that the canthomeatal
line forms a 37 degrees angle
with the image receptor.
 If the patient's mouth is open, the
sphenoid sinus will be seen
superimposed over the palate.
 The central beam is
receptor and centered in the area
of maxillary sinuses.
Technique

 It is primarily used to demonstrate the
maxillary sinus, frontal and ethmoidal sinuses.
 The sphenoidal sinuses are seen if the patient
is asked to open his/her mouth.They are
projected on the palate.

 Investigation of the maxiliary antra.
◦ Le Fort I
◦ 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).
Indications

PROJECTIONS FOR
PARANASAL SINUSES
[PA projections (occipito-
frontal projections for nasal
sinuses)]

 The image receptor is placed
in front of the patient,
perpendicular to the mid
sagittal plane and parallel to
coronal plane, so that the
canthomeatal line is
receptor.
 The central ray is directed to
the midline of the skull so that
the X-ray beam passes
through the cantomeatal line
Technique

Caldwell’s projection
(modified method of PA)

 This view is also known as the frontal sinus view.
 This position is ideally suited for studying frontal
sinuses. In this position the frontal sinuses are in direct
contact with the film hence there is no chance for any
distortion or geometric blur to occur.

 The cassette is placed
perpendicular to the
floor.
 The patient is made to
sit in front of the film
with the radiographic
base line tilted to an
angle of 15 - 20 degrees
upwards.
 The incident beam is
horizontal and is
centered 1/2 inch below
the external occipital
protruberance.

Frontal sinus
Superior
orbital fissure
Ethmoid sinus
Petrous part
of temporal
bone
Maxillary sinus

 The lateral one fourth to one third of the condyle is
best visualized with the transcranial projection
because the x-ray beam is tangential to the superior
surface of the lateral pole.
 As a result the central and medial structures are
superimposed on the radiographic image, inferior to
the visualized lateral pole.

 The cassette is placed flat against the patient’s ear and
centered over the TM- joint of interest, against the facial skin
parallel to the sagittal plane.
 The patient's head is adjusted so that the sagittal plane is
vertical.
 The ala-tragus line is parallel to the floor.
 This view is taken with both open and closed position.

 There are 3 techniques for transcranial view
 In all the 3 techniques the central ray is directed
caudally at an angle of 200
to 250
.
 The point of exit is through the TM joint of interest.

 In Lindblom technique (1936), central ray
entered half inch behind and 2 inches above
Technique

 It shows the lateral aspect of TMJ.
Structures seen are
◦ Glenoid fossa
◦ Articular eminence
◦ Joint space
◦ Condylar head

 Assessment of Joint Space and Condylar Position
and their relationship.
 Detection of Osseous Disease. Significantly, the
earliest arthrotic changes tend to occur on the crest
of the articular eminence.
Indications

The information provided by the closed view includes:
 The size of the joint space- this provides indirect information
about the position and shape of the disc.
 The position of the head of the condyle within the fossa.
 The shape and condition of the glenoid fossa and articular
eminence (on the lateral aspect only).
 The shape of the head of the condyle and the condition of the
articular surface (on the lateral aspect only)
 A comparison of both sides.
Diagnostic information

The information provided by the open view includes:
 The range and type of movement of the condyle.
 A comparison of the degree of movement on both
sides.

 It is a lateral projection showing medial aspect of
condylar head and neck.

 The cassette is placed flat
against the patient’s ear, over
the TM joint of interest, against
the facial skin parallel to the
sagittal plane.
 The patient is positioned so
that the sagittal plane is
vertical and parallel to the
film.The patient is instructed
to slowly inhale through the
nose during exposure.
 The patient should open mouth

from the opposite side
cranially, at an angle of -5 to -
10 degrees posteriorly.
 It is directed through the
mandibular notch, that is a
window between the
coronoid, condyle and the
zygomatic arch, of opposite
side below the base of the
skull to the TM joint of
interest.
Technique

 To visualize erosive changes of the condyle.
 To evaluate the fracture of condylar head and neck.
 Any pathological conditions affecting the condyle.
Indications

 The film behind the patient’s
head at an angle of 45
degrees to the sagittal
plane.
 The patient is positioned so
that the sagittal plane is
vertical.
 The canthomeatel line
should be 10 degrees to the
horizontal, with the head
tipped downwards.The
mouth should be wide open.
 The tube head is placed in front
of patient’s face.
 The central ray is directed to
the joint of interest, at an angle
of +20 degrees, to strike the
cassette at right angles.
 The point of entry may be taken
at:
◦ Pupil of the same eye, asking the
patient to look straight ahead.
◦ Medial canthus of the same eye
◦ Medial canthus of the opposite eye
Technique

The anterior view of the temporomandibular
joint

 It is the anterior view of TMJ.
 Osseous changes of the condyle can be seen.
 Fracture involving condylar head and neck are best
evaluated.
Indications

front of the patient, perpendicular to
the midsagittal and parallel to the
coronal plane.
 The patient’s head is tilted
downward so that the canthomeatal
line forms a 25 to 30 degree angle
with the image receptor.
 Exposure parameter:
 KVp=65-70
 mA=7-10
 Seconds=2-3
 To improve visualization of the
condyles, the patient’s mouth is
opened so that the condylar
heads are located inferior to
the articular eminence.
 The central beam is
receptor and parallel to
patient’s midsagittal plane and
it is centered at the level of the
condyles.
Technique

 Primary mean to view condylar neck and head
 High fractures of condylar neck, intracapsular
fractures of the TMJ
 Condylar hypoplasia or hypertrophy
Indications

 White and Pharoah- oral radiology 6th
edition.
 White and Pharoah- oral radiology 5th
edition.
 Freny R Karjodkar.Textbook of and dental and
maxillofacial radiology.2nd
edition. 2011.
 A guide to Dental Radiology 3rd
edition – Rita A.Mason
 Eric Whaites. Essentials of dental radiography and
radiology.3rd
edition.2003.
References

OMRD extraoral radiography-final (1).pptx

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