Radiography Of The Temporomandibular Joint

Radiography Of The Temporomandibular Joint

Write short note on various radiographic views to visualize temporomandibular joint pathologies.
or
Write short answer on transorbital views.
or
Write short answer on radiographic views used for TtMJ disorders.
Answer. Following are the various radiographic views to visualize temporomandibular joint:

• Transcranial projection
• Transpharyngeal projection
• Transorbital projection
• Reverse Towne’s projection.

Tranpharyngeal Projection

This view is a lateral projection which shows medial surface of condylar head and neck.

Film Placement

Cassette should be placed flat against the ear of patient and is centered to a point half inches anterior to external auditory meatus over temporomandibular joint of interest against the facial skin parallel to sagittal plane.

“Understanding the role of radiography in diagnosing TMJ disorders: Q&A explained”

Patient’s Position

• Patient is positioned in such a manner that sagittal plane is vertical and parallel to the film and the temporomandibular joint of interest is adjacent to film.
• Occlusal plane should be parallel to transverse axis of film so that soft parts of nasopharynx should be in one line with temporomandibular joint.
• Patient is told to slowly inhale through the nose at the time of exposure to ensure filing of nasopharynx with air at the time of exposure.
• Patient should open his mouth.

“Importance of studying TMJ radiography for better imaging outcomes: Questions explained”

Central Ray

• Directed from opposite side cranially from angle of –5 to –10° posteriorly.
• Ray is directed via mandibular notch in a window between coronoid, condyle and zygomatic arch of opposite side below base of skull to TMJ of interest.

“Common challenges in performing TMJ radiography effectively: FAQs provided”

Exposure Parameters

By Intraoral X-ray Machine

kVp: 65 to 70

mA: 7 to 10

Seconds: 0.8

By Extra-oral X-ray Machine

KVp: 40

mA: 40

Seconds: 1

Transorbital Projection (Zimmer Projection)

It is most successful in delineating the joint with minimum superimposition and lead to production of relatively true projection.

TMJ panoramic radiography

Structures shown

Anterior surface of TMJ, medial displacement of condyle and fractured neck of condyle.

Film Position

It is positioned behind the head of patient at an angle of 45° to sagittal plane.

Patient’s Position

• Positioning of patient should be in such a way that sagittal plane is vertical.
• Canthomeatal line is 10° to horizontal with head tipping downwards.
• Patient is asked to widely open the mouth.

“Factors influencing success with TMJ radiography techniques: Q&A”

Central Ray

• Head of the tube should be in front of the face of patient.
• Central ray is directed over the TMJ of interest at an angle of +20°, to strike the cassette at right angles.
• The point of entry may be taken at.
  • Pupil of same eye, asking the patient to look straight ahead
  • Medial canthus of same eye
  • Medial canthus of opposite eye.

“Role of counseling in clarifying TMJ radiography goals for patients: Questions answered”

Exposure Parameters

By Intraoral X-ray machine

kVp: 65 to 70

mA: 7 to 10

Seconds: 0.8

Best X-ray for TMJ diagnosis

By Extraoral X-ray Machine

kVp: 40

mA: 40

Seconds: 1

“Steps to explain types of TMJ radiographs: Panoramic vs CBCT: Q&A guide”

Reverse Towne’s Projection

It is used for viewing condylar head and neck, fracture of neck of condyle, intracapsular fracture of TMJ, condylar hypoplasia or hyperplasia.

Film Position

It is placed perpendicular to the flor in a cassette-holding device. Long axis of cassette is placed vertical.

Patient’s Position

• Sagittal plane should be vertical and perpendicular to the film.
• Film is adjusted in a manner such that lips centered over the film.
• Patient’s forehead should touch the film.

TMJ Radiography: X-ray Views and Diagnostic Applications

“Role of panoramic radiography in TMJ imaging: Questions answered”

Central Ray

Directed through mid-sagittal plane at mandible and perpendicular to the film.

Exposure Parameters

By Extraoral X-ray Machine

KVp: 70–80

mA: 60–50

Seconds: 1.6 (bucky grid)