EXTRAORAL RADIOGRAPHY

PRESENTED BY- GAURAV KATHERIYA

JR3

• Introduction

• Types Of Extraoral Radiography And Slight Elaboration

About Techniques

– Indications

– Landmarks

– Interpretations

• Overview

• Extraoral radiographs (outside the mouth) are

taken when large areas of the skull or jaw must be

examined or when patients are unable to open

their mouths for film placement.

• 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.

Historical aspect

Extra-oral Source

Discovered by

Dr. Hisatugu Numata of Japan, 1933

Father of Panoramic Radiography

•1949, extra-oral films

•X-ray source - stationary

Dr Yrjo Veli Paatero

Indication

• When it is not possible to place the film intraorally as

during trismus.

• To examine the extent of large lesions, especially when

the area of pathology is greater than which can be covered

by an intraoral periapical film.

• When jaws or other facial bones have to be examined for

evidence of disease lesions and other pathological

conditions.

4.To evaluate skeletal growth and development.

5. To evaluate the status of impacted teeth.

6. To evaluate trauma.

7. To evaluate temporomandibular joint area

Drawbacks

• Magnification occurs due to the greater object to

film distance used.

• Details are not well-defined due to the use of cassettes

and intensifying screens.

• For optimum balance between loss of image detail and

reduction of patient exposure medium or high speed

screen,film combinations should be used.

• Contrast is reduced as the secondary radiation

produced by the soft tissues is more.

Definition of Some Extraoral Landmarks

used for Patient Positioning

The Median Plane of the Head

• (Midsagittal Plane)

• line that is coincident with the sagittal suture between the

upper margins of the parietal bones, running from the top

of the skull backwards.

• The Infraorbital Line

This line runs across the face from one infraorbital

margin to the other.

• The Orbitomeatal Line (Canthomeatal Line)

This is an imaginary line from the outer canthus of the

eye to the tragus of the ear.

• This is known as the radiological base line and joins the

upper edge of the auditory meatus with the outer canthus

of the eye.

Fig. 12.1: Diagram showing external guide line used for patient

positioning: 1. Glabellomeatal line,

2. Orbitomeatal line, 3. Inframeatal line, 4. Acanthomeatal line

The Frankfort Horizontal Line

• Is the line which runs from the most inferior portion

of the infraorbital margin of the orbit to the highest

point on the superior surface of the external auditory

meatus.

Most Commonly Used Views For

Maxillofacial Imaging

A. Radiography of Sinuses

• 1. Posteroanterior Projection (also known as occipito frontal

projection of Nasal Sinuses)

There are 2 methods for obtaining this projection.

• a. Posterior Anterior (Granger Projection).

• b. Modified method, Inclined Posterior Anterior (Caldwell

Projection).

• Standard Occipitomental Projection (O° OM)

• Modified Method (30° occipitomental projection)

• Bregma Menton

• PA Water’s

C. Radiography of the Mandible

1. PA Mandible

2. Rotated PA Mandible

3. Lateral Oblique

Anterior body of mandible

Posterior body of mandible

Ramus of mandible

• D. Radiography of Base of the Skull

1. Submento Vertex projection

• E. Radiography of the Zygomatic Arches

1. Jughandle view (A Modification of submentovertex view)

• F. Radiography of the Temporomandibular Joint

1. Transcranial Projection

2. Trans Pharyngeal Projection

3. Trans Orbital Projection

4. Reverse Towne’s Projection

5. Dental panoramic tomograph (including specific TMJ field

limitation techniques)

6. Tomography, both linear and spiral.

G. Radiography of the Skull

• Lateral cephalogram

• True lateral

• PA cephalogram

• PA Skull

• Towne’s Projection

RADIOGRAPHY OF THE

PARANASAL SINUSES

• study the relationship of the sinuses to each other and to the

surrounding structures.

1. Posteroanterior Projection (also known as the Occipitofrontal

Projection of the Nasal Sinuses):-

• two methods for obtaining this projection:-

• A. Posteroanterior (Granger) Projection.

• B.Modified Method, Inclined Posteroanterior(Caldwell) Projection

A. Posteroanterior (Granger) Projection.

OF / PA VIEW1. Nasal Septum

2. Frontal Sinus

3. Maxillary Sinus

4. Ethmoid Sinus

5. Inferior Turbinate

6. Superior orbital fissure

7. Sagittal suture

8. Coronal suture

9. Sphenoid ridge

10. Mastoid process

11. Hard palate

12. Innominate line

13. Petrous ridge

2

1

4

3

5

6

7

8

9

10

12

11

13

Structures Shown

• excellent for evaluating the inner and middle ear

because the petrous pyramid can be viewed through

the orbits.

B.Modified Method, Inclined Posteroanterior

(Caldwell) Projection

• Also known as Occipitofrontal View Or Nose Forehead

Structure Seen:-

1. Frontal Sinuses (Seen Best)

2. Ethmoid Sinuses

3. Maxillary Sinuses

4. Frontal Process Of Zygoma And Zygomatic Process Of

Frontal Bone

5. Superior Margin Of Orbit And Lamina Papyracea

6. Superior Orbital Fissure

RADIOGRAPHY OF THE MAXILLARY

SINUSES

A.Standard Occipitomental Projection (0° OM)

This projection shows the facial skeleton and

maxillary antra., and avoids superimposition of the dense

bones of the base of the skull.

Indications:-

• Investigation of the maxillary antra

• Detecting the following middle third facial fractures

(using Campbell lines) :

• — 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).

• Examine the 0° OM using an approach based

• broadly on that suggested originally by

• McGrigor & Campbell (1950), often referred

• to as Campbell's lines.

B.Modified Method (30° Occipitomental

Projection)

• also shows the facial skeleton, but from a different angle from

the 0° OM, enabling certain bony displacements to be

detected.

• Main indications

• The main clinical indications include:

• • Detecting the following middle third facial

• fractures:

• — LeFortI

• — Le Fort II

• — Le Fort III

• Coronoid process fractures

3. Bregma Menton

Structures Shown

• 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.

4. PA Water’s

• Structures seen

• maxillary sinus, frontal and ethmoidal sinuses.

• The sphenoidal sinuses can be seen if the patient is

asked to open his mouth, whereby the sphenoidal

sinuses are projected on the palate.

• The orbit, frontozygomatic suture, nasal cavity,

coronoid process of the mandible and the zygomatic

arch are also seen.

C. Radiography of the Mandible

I. PA Mandible

•A posteroanterior projection

of the mandibular body and

the ramus.

•The symphysis region is not

well seen because of the

superimposition of the spine.

Indications

• used to study fractures of the posterior third of the

body of the mandible, angles, rami and lower

condylar neck

• mediolateral expansion of the posterior third of the

body or the rami in case of tumors or cystic

lesions,maxillofacial deformities and mandibular

hypoplasia or hyperplasia.

2. Rotated PA Mandible

• used to show the tissues

of one side

• of the face and used to

investigate the parotid

gland

• and the ramus of the

mandible.

Indications

• Stones/calculi in the parotid glands

• Lesions such as cysts or tumours in the ramus to note

any medio-lateral expansion.

• Submasseteric infection — to note new bone

formation.

A. Anterior Body of the Mandible

• Anterior body of the

mandible, position of

the teeth in the same

area.

indications

• evaluate impacted teeth

• fractures

• lesions located in the anterior portion of the

mandible

B. Posterior Body of the Mandible

• Structures seen

• Body of the mandible, position of the teeth in the

• same area, ramus of the mandible, angle of the

• mandible

Indications

• evaluate impacted teeth

• fractures

• lesions located in the posterior border of the

mandible.

C. Ramus of Mandible

• Structures seen

• a view of the ramus

from the angle of the

mandible to the

condyles.

indications

• to evaluate impacted third Molars

• large lesions

• fractures that extend into the ramus of the mandible.

RADIOGRAPHY OF THE BASE OF THE

SKULL1. Submento vertex Projection

Structures seen

• the base of the skull

sphenoidal sinuses

facial skeleton from

below.

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.

RADIOGRAPHY OF THE ZYGOMATIC ARCHES1. Jug Handle View (A Modification of the

Submentovertex View)

Structure seen

• A symmetrical axial view of the zygomaticarches.

RADIOGRAPHY OF THE TEMPORO

MANDIBULAR JOINTS

1. Transcranial

Structure seen

• Lateral aspect of:

• Glenoid fossa

• Articular eminence

• Joint space

• Condylar head

Indications

• TMJ pain dysfunction syndrome

• Internal derangements of the joint producing

pain,clicking and limitation in opening

• To investigate the size and position of the disc

• this can only be inferred indirectly from the

• relative positions of the bony elements of the joints

• To investigate the range of movement in the joints.

Diagnostic information

• Open mouth

• The range and type of movement

of the condyle

• A comparison of the degree of

movement on both sides.

• Closed mouth

• The size of the joint space.

• 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.

2. Transpharyngeal (Infracranial or McQueen

Dell Technique)

Structure seen

• Lateral view of:

• Condylar head and neck

• Articular surface

Indications

• TMJ pain dysfunction syndrome

• To investigate the presence of joint disease,particularly

osteoarthritis and rheumatoid arthritis

• To investigate pathological conditions affecting the

condylar head, including cysts or tumours

• Fractures of the neck and head of the condyle

3. Transorbital (Zimmer Projection)

• conventional frontal TM

joint projection.

Structures seen

• The anterior view of the

temporomandibular joint

• Medial displacement of

fractured condyle

• Fracture of neck of condyle

are clearly seen in this view.

4. Reverse Towne’s

Structures seen

• Posterior view of both

condylar heads and

necks

Indications

• To investigate the articular surface of the condyles

and disease within the joint

• Fractures of the condylar heads and necks

• Condylar hypo/hyperplasia

SKULL PROJECTION

1. Lateral Cephalogram

• Indications:-

• 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

• 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.

2. True Lateral

Structure seen

• shows the skull vault

and facial

• skeleton from the lateral

aspect.

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:

• — tumour of the pituitary gland in acromegaly.

3. PA Cephalogram

• This projection is identical

to the PA view of the

• jaws, except that it is

• standardized and

reproducible. This makes it

suitable

• for the assessment of facial

asymmetries and

• for preoperative and

postoperative comparisons

in

• orthognathic surgery

involving the mandible.

indications

• used for the assessment of facial asymmetries

• preoperative and postoperative comparisons in

• orthognathic surgeries involving the mandible

4. PA Skull

• Structures seen

• the skull vault, primarily

• the frontal bones and the jaws

indications

• Fractures of the skull vault

• Investigation of the frontal sinuses

• Conditions affecting the cranium, particularly:

• — Paget's disease

• — multiple myeloma

• — hyperparathyroidism

• Intracranial calcification

Towne’s Projection

• Structures seen

• the occipital area of

• the skull. The necks of the condyloid process can

• also be viewed.

‘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

Advantages

• All the teeth and their supporting structures

are shown on one film.

• The technique is reasonably simple

• The radiation dose is relatively low, particularly

with modern DC units with rare-earth intensifying

screens — the dose is equivalent to about three to four

perapical radiographs.

Demerits

• Only structures within the section will be evident and

in focus on the final film.

• image quality is inferior to that of intraoral (periapical

and bitewing) radiographs and interpretation is more

complicated

Indications

• Orthodontic assessment where there is a clinical need

to know the state of the dentition and the

presence/absence of teeth

• To assess bony lesions or an unerupted tooth that are

too large to be demonstrated on intraoral films

• Prior to dental surgery under general anaesthesia

• As part of an assessment of periodontal bone support

where there is pocketing greater than 5 mm

• Assessment of third molars, at a time when

consideration needs to be given to whether they

should be removed or not.

• Fractures of all parts of the mandible except the

anterior region

• Antral disease — particularly to the floor,posterior

and medial walls of the antra

• Destructive diseases of the articular surfaces of

theTMJ

• Vertical alveolar bone height as part of preimplant

planning.

BONY LANDMARKS IN MANDIBLE

97

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 foramen 10. Genial tubercle

13. Lingula

12. External Oblique Ridge

14. Hyoid bone

8

9

1011

1213

BONY LANDMARKS IN MAXILLA

98

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

1718

19

2021

22 2329

25

24

26

28.Pterygo max. fissure

30. Maxillary tuberosity29.Spine of the sphenoid bone 31. Lateral pterygoid plate

31

30

28

27

OTHER STRUCTURES

99

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

Overview

• Overview

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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.