TMJ RADIOGRAPHY

Enumeration & Classification

• Plain film Radiography(1900)�Transcranial�Transpharyngeal�Transorbital�Reverse Townes�Sub- mento vertex view�
• Panoramic Radiography (1960)
• Tomography�Conventional �Computed Tomography�Cone Beam Computed �

• Arthrogram(1970)�Arthrography

Arthroscopy�MRI (1984)

• Miscellaneous Modalities�Ultrasound�Radionuclide Imaging�Thermography�

Based on Principle�Hard / Soft tissue

Screening / Diagnostic

Plain Film Radiography

• Advantages - Less time, Conventional machines
• Disadvantages- only mineralized part, superimposition; visualize,multiple angles
• Transpharyngeal
• Transcranial
• Transorbital
• Facial projections

Reverse Townes�Sub- mento vertex view�

• Transcranial view

• Sagittal view of lateral aspect of condyle and temporal component.
• Identify gross osseous changes on

1) lateral aspect of the joint

2) Displaced condylar fracture

3) range of motion

Arthritic changes in articular surfaces

Evaluate joints bony relationship

Film placement

• Cassette is placed on the surface of the ear
• Centered over the tm joint
• Film is parallel to the sagital plane

Patient position

• Patient s sagital plane should be

perpendicular to floor.

• Ala- tragal line should be parallel to floor

Central x-ray

Is directed at vertical angulation 25⁰

½”behind and 2”above the auditory meatus.

Sagittal plane

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Central ray 25

red arrow = head of condyle

black arrow = glenoid fossa

• Transpharyngeal

(Infracranial or Mc Queen Dell technique)

Structures seen

• Condylar head and neck
• Sagittal view of the medial pole

of the condyle

Indication

• Fracture of the Condylar head
• Erosive changes of condylar head

Film placement

½” ant to the E A M

POSITION OF THE PATIENT

• Sagital plane is parallel to film
• Inhale through nose during exposure
• Patient should open his mouth

Central x-ray

• Directed from opposite side cranially
• Angle of -5 to -10 Posteriorly
• Directed through the mandibular notch

• Trans orbital projection

(Zimmer projection)

This is the conventional frontal TMJ joint projection which

is most successful.

Structure seen

• Articular surface
• Articular eminence

• It is perpendicular to trans cranial.
• Mediolateral dimension of Articular eminence, condylar neck , head is visible.
• Condylar neck fracture

Patient position

• Sagital plane is perpendicular to floor
• Canthomeatal line 10⁰ to horizontal
• Head tipped downwards.
• Mouth is wide open

Central x-rays

• Tube is placed in front of the face
• Ray is directed+20 angulation

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Point of entry

• Pupil of the same eye
• Medial canthus of the same eye
• Medial canthus of the opposite eye

Film position

• Film placed behind the head at an angle 45⁰ to the sagital plane

Panoramic view

• Panoramic helps in screening any odontogenic diseases and other disorders .
• Gross osseous changes in condyle may be seen.

Reverse Towne's

• PA with open mouth
• Define all but the most superior parts of condylar process
• Condylar neck & head
• CLINICAL CONSIDERATION

fractures of condylar neck- unilateral/bilateral

Intra capsular fracture of TMJ

Unfavorable fracture- superomedial displacement

Condylar hypo/hyperplasia

Reverse Towne's

• Technique

Submentovertex View

• To determine the angulations for corrected Tomogram

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• to study facial asymmetries and to reveal condylar displacements and rotation in the horizontal plane associated with trauma or orthognathic surgery.
• ruling out TMJ erosions from nasopharyngeal carcinoma

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Submento Vertex View

• Technique

Conventional tomography

• Morphological abnormalities or erosive changes of the condylar head are suspected.
• Entire condylar head is visible in Mediolateral plane .

Computed Tomography

Advantages

• 3D - Bony images- different planes
• Disc is thickened/ shape is altered

Disadvantages

• Cost, availability, radiation exposure, pt co-operation
• Clinical consideration
• Presence & extent of ankylosis neoplasams
• Bone involvement in arthritides
• Complex fractures
• Shape of condyle,fossa, eminence
• Articulating surface

CT

Cone Beam Computed Tomography

• Advantages
• Low radiation exposure
• Cost
• Disadvantage
• Pt – stationary
• Soft tissue
• Artifacts/ streaks
• Facility not widely available

Cone beam Computed Tomography

• Clinical indication
• Full assessment of the whole joint to determine the presence & site of any bone disease / abnormality
• To investigate the condyles & condition of articular fossa when pt is unable to open mouth
• Assessment of fractures of condylar head & articular fossa & intracapsular fractures
• Diagnostic information
• Shape of condyle & condition of articular surfaces
• Condition of glenoid fossa & eminences
• Nature of any disease affecting condylar heads

Radiographic investigation to examine different aspects of TMJ

• Transcranial Lateral aspect of glenoid

fossa,articular eminence

joint space,condylarhead

• Transpharyngeal Lateral aspect of condylar

head, articular surface

• OPG Lateral view of both condylar

heads lying within focal trough

• Reverse Towne’s Posterior view of both condylar

heads & necks

• Transorbital Anterior view of condylar head & neck,

articular surface

• Tomography All aspects of glenoid fossa, articular eminence, joint

space , condylar head

Arthrography

• Arthrography - x-ray examination of a joint space
• Real time imaging

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• Non – ionic aqueous contrast mediume (eg-iopamidol- Niopam)- fluoroscopy
• TMJ arthrography is indicated for evaluating soft-tissue components, especially disk position, function, and morphology (eg, perforation, swelling, adhesions)
• Position, shape & condition of disc
• Perforations & adhesions

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Arthroscopy

• Arthroscopy is a technique of introducing an optical instrument into the joint allowing direct visual examination
• Invasive diagnostic approach
• Diagnostic as well as theraupetic
• Patients with signs and symptoms of intracapsular disorders such as disc displacement, hypomobility, osteoarthritis,and synovitis with adhesive capsulitis; unresponsive for at least3 months of conservative therapy are candidates for TMJ arthroscopy.

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MRI

• MRI- Gold standard- good quality images - excellent definition of soft and hard tissue structures.�
• Advantages- no radiation, no harmful biological effect , operator independent, multiple planes (disc displacement)
• Disadvantages - high cost, its inability to visualize perforations of the posterior attachment or of the disk.

MRI

• INDICATION FOR TMJ soft tissue imaging are
• Determination of position, function, and form of the disk
• D/d of pts with facial pain of unclear etiology
• D/d of pts with headache aggravated by jaw function
• Disk displacement or deformation
• Joint effusion
• Bone marrow edema
• Tumors

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Image Findings – Normal Joint

• y

Clinical Consideration

• Bony ankylosis- CT, Conventional tomography, MRI
• Remodeling - CT, Conventional Tomography, Transcranial, Transpharyngeal, Transorbital
• Arthridites - CT,MRI, Conventional Tomography, Transcranial , Panoramic, Transpharyngeal, Transorbital
• Developmental: (Arthrography); CT, conventional, panoramic
• Neoplasam- CT, MRI,Conventional Tomography
• Trauma – Transorbital, CT; Panoramic, SMV, Conventional, MRI
• RANGE OF MOTION- Transcranial, Conventional , Arthrography; MRI
• Asymmetry- Panaromic, conventional ,SMV(MRI, Arthrography)

CLINICAL CONSIDERATION

• Disk position- MRI, Arthrography; CT
• Disk perforation- arthrography
• Fibrous ankylosis- MRI, Arthrography
• Joint effusion- MRI, Arthrography
• Inflammatory condition- MRI, Arthrography
• Joint space calcification- CT, Conventional, MRI, Transcranial, Transpharyngeal

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