EXTRAORAL RADIOGRAPHY

Terminology

Posterior view Lateral view Axial view Sagittal plane Radiographic base line= canthomeatal

line ( outer canthus of eye to external auditory meatus)

Parallel ║, perpendicular ┴ Central beam

Cassette with intensifying screen Grid Bucky table

Cephalometric and skull views:1. Lateral skull/ lateral Cephalometric projection

○ True lateral skull view

2. Submentovertex (base)view

3. Waters view○ standard occipitomental view (0º OM)○ 30º OM

4. PA skull/ ceph○ Rotated PA

5. Reverse-Towne (open mouth)

Mandibular oblique lateral1. Mandibular ramus view

2. Mandibular body view

Lateral Skull/ Lat Ceph Film║ to midsagittal plane Central beam ┴ to film

True lateral skull view

Indications Fractures of cranium and cranial baseMiddle third facial fracturesTo investigate frontal, spenoidal and maxillary

sinusesDiseases of skull e.g

○ Paget’s○ Multiple myeloma○ Hyperparathyroidism ○ Tumors of sella tursica

P A skull view (occipito-frontal) view CM line at 10º to film Central beam ┴ to film

Indications Fractures of skull vault, mandibular fractures

( post. third of body, angle, rami, low condylar neck)

Frontal sinus Conditions effecting cranium, intra cranial

calcifications Mandibular and maxillofacial deformities,

tumors, cysts.

Rotated PA view (puff cheek/ cheek tangential)

Indications

Stones/ calculi in parotid glands Cysts/ yumors in ramus- to note medio-lateral

expansion Submesseteric infections- to node new bone

formation.

Waters view (PNS view) CM line at 37º with film Central beam ┴ to film Mouth open- spenoid sinus

seen

Indications Investigations of sinuses

Mainly maxillary antrumFrontal. Ethmoidal, sphenoidal (open mouth- seen on

palate) Fractures

Middle third fractures= Le Fort I, II, IIIZygomatic complex fractures, naso-ethmoidal, orbital

blow out.Coronoid process fracture

Submentovertex view (SMV) CM line ║ to film Central beam ┴ to film

Indications Fracture of zygomatic arches- these thin bones

are seen with reduced exposure= jug handle view

Destructive/ expansive lesions effecting palate, pterygoid region, base of skull

Sphenoidal sinuses

Reverse Towne view CM line -30º with film Central beam ┴ to film

Indications

Towne’s view= AP view High fractures of condylar necks Intracapsular fractures of TMJ Condylar hypoplasia and hyperplasia

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Caldwell Sinus Projection The Caldwell Projection

will have the petrous ridges below the orbits.

Positioning is exactly like the P-A skull with the exception of the use of a 15 degree caudal tube angle to lower the petrous ridges.

Madibular oblique lateral views

Receptor size minimum 5 x 7 inch (13 x 18 cm)

Mandibular oblique lateral body view Film in contact with cheek at molar area Central beam aims at molar-premolar area

Mandibular oblique lateral ramus view Film in contact with cheek at ramus area Central beam aims at ramus area

Summary