Temporomandibular Joint Projection Question And Answer

Temporomandibular Joint Projection Question And Answer

Question 1. Describe transcranial projection with its indications.
Answer: Transcranial projection is otherwise known as Lindblom projection.

This view is used for the evaluation of:

• The superior surface of the condyle
• The translation of the condylar processes
• The surface of the articular eminence.

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Transcranial projection Technique:

• The cassette should be placed parallel to the patient’s midsagittal plane, centering the condyle of interest.
• The central ray is directed downward from the opposite side. It enters ^ inch posterior to the external auditory meatus and 2 inches above the external auditory meatus.
• Vertical angulation: + 25°
• Average horizontal angulation: 20°.
• Series of right and left TMJ in the closed and maximal open positions should be taken.

Transcranial projection Indications:

• To diagnose:
  • Displaced condylar fractures
  • Range of condylar motion
  • Disc position
  • Gross osseous changes on the lateral aspect of the jaw.

Transcranial projection Limitations: Condyle, temporal component, and joint spaces are shattered on the image.

Question 2. Describe trans pharyngeal projection.
(or)
Describe parma projection.
Answer:

This view is indicated for:

• Visualization of the superior surface of the condyle
• Screening arthritic changes.

Transpharyngeal projection Techniques:

• Patient is asked to hold the cassette against the head and turn 7° to 10° away from the side of interest. The cassette should be parallel to the midsagittal plane.
• The central ray is directed through the coronoid notch on the opposite from 0° to -5° perpendicular to the cassette.
• The patient should be instructed to widely open the mouth when the exposure is made.
• Exposure factors must be 70 kV 10 mA, and 0.1 seconds. The exposure time is greatly reduced because no bony structures are superposed.Transpharyngeal projection Limitation: Temporal component cannot be imaged accurately.

Question 3. Describe transorbital projection.
(or)
Describe Zimmer projection.
Answer:

This view is indicated for:

• Visualization of the superior surface of the condyle from the lateral to medial poles
• Condylar neck fracture.

Transorbital projection Techniques:

• The cassette should be placed behind the patient’s head.
• The patient should open the mouth at the maximal level or protrude the mandible to position to avoid the superimposition of the articular eminence or skull base over the condyle.
• Central ray should be directed downward at + 35° through the patient’s medial canthus, centering the condyle within the orbit. The patient’s head is rotated approximately 20° toward the side of interest to avoid superimposition of the mastoid process over the structures of interest.
• Exposure factors must be 75 kV 15 mA, and 0.1 seconds.

Question 4. Discuss about temporomandibular joint tomography. (or)
Describe the panoramic projection of the temporomandibular joint.
Answer:

• The panoramic TMJ view is principally used for screening the morphology of condyle and initial assessment of condylar translation. It is also used to detect the early changes associated with rheumatoid arthritis or degenerative joint disorders.
• TMJ tomography is a technique used to examine structures located within a selected plane of tissues while blurring the structures outside the plane. TMJ tomography provides the most definitive imaging of the bony components of TMJ and the glenoid fossa.
• It is also used to examine the joint space and evaluate the movement of the condyle in the open mouth position. This view has limited application and provides a distorted image of the joint due to its thick image layers.

Transorbital projection Limitations:

• Condylar position and movements cannot be interpreted.
• Not ideal for early diagnosis of mild osseous changes.

Question 5. Role of computed tomography in the diagnosis of temporomandibular joint disorders.
Answer:

Computed tomography (CT) is helpful in providing detailed information about the internal joint structures both osseous and soft tissues in a three-dimensional shape. It produces multiple image slices in axial and coronal planes which are manipulated and form images in the sagittal plane.

Temporomandibular joint disorders Applications:

• Computed tomography images are valuable in the diagnosis of:
  • Ankylosis
  • Neoplasm
  • Bone involvement in TMJ arthritis
  • Complex joint fractures.

Temporomandibular joint disorders Limitations: Articular disc changes cannot be studied precisely.

Question 6. Temporomandibular arthrography.
Answer:

• Arthrography is useful in viewing TMJ disc pathology. It is taken by injecting the radiopaque iodine dye as a contrast agent into the joint space under fluoroscopic guidance through the preauricular or transmittal portal.
• In this way, this image is helpful in detecting the disc perforation and adhesion by the way the contrast agent fills the joint space.

Arthrography Applications:

• To study the:
  • Disc position, structure, and function
  • Disc attachments.

Question 7. Radiographic features of TMJ ankylosis.
Answer: TMJ ankylosis is of two types: True (bony) or false (fibrous).

1. True ankylosis results from condyle or ramus attachment with the temporal bone.
2. Fibrous ankylosis results from the soft tissue union of the joint components
   • Coronal CT images are the best to diagnose ankylosis.

Bony Ankylosis:

• The joint space is either partially or completely obliterated by an osseous bridge
• There is a fusion of the condyle to the cranial base
• Elongation of the coronoid process and deepening of the antennal notch on the affected side.

Fibrous Ankylosis:

• The articular surfaces are eroded and appear irregular.
• The joint space appears narrow.
• Two irregular joint space may appear to fit one another and gives the appearance of a characteristic jigsaw puzzle.

Temporomandibular Joint Projection Viva Voce

Question 1. What is the use of submentovertex projection in the diagnosis of temporomandibular joint disorders?
Answer: The submentovertex (SMV) or basal projection is useful in the evaluation of facial symmetries, and condylar displacement, and to detection the horizontal rotation of the mandible following trauma or orthognathic surgeries.

Question 2. What are Ely cysts?
Answer: Ely cysts are the pseudo cysts seen in degenerative joint disorders (TMJ osteoarthritis). In radiographs, they appear as small, round radiolucent lesions surrounded by radiopaque boundaries below the articulating surfaces. These cysts denote the presence of fibrous tissues, granulation tissues, and osteoid structures as a degenerative change.

Temporomandibular Joint Projection Question And Answer Multiple Choice Questions

Question 1. The articular disc is best viewed in.

1. Arthrography
2. Computed tomography
3. Magnetic resonance imaging
4. Panoramic tomography

Answer: 3. Magnetic resonance imaging

Question 2. Joint inflammation and effusion are studied in.

1. T2—weighted magnetic resonance images
2. T1—weighted magnetic resonance images
3. Proton—weighted magnetic resonance images
4. Motion magnetic resonance studies

Answer: 1. T2—weighted magnetic resonance images

Question 3. In unilateral internal derangements, the mandible deviates to the.

1. Normal side on opening
2. Affected side on opening
3. Normal side on closing
4. Affected side on closing

Answer: 4. Affected side on closing

Question 4. Disc perforation is best studied in.

1. Arthrography
2. Computed tomography
3. Magnetic resonance imaging
4. Panoramic tomography

Answer: 1. Arthrography

Question 5. Resistance to injection of contrast agent in the joint space indicates.

1. Adhesion
2. Perforation
3. Reduction
4. Displacement

Answer: 1. Adhesion

Question 6. Joint mice denote.

1. Fibrous tissues
2. Granulation tissues
3. Broken osteophytes
4. Ely cysts

Answer: 3. Broken osteophytes

Question 7. Sharpened pencil appearance of the condyle is seen in.

1. Osteoarthritis
2. Rheumatoid arthritis
3. Fibrous ankylosis
4. Osseous ankylosis

Answer: 2. Rheumatoid arthritis

Question 8. The sharpened pencil appearance of the condyle denotes the.

1. Condylar hyperplasia
2. Condylar hypoplasia
3. Condylar erosion
4. Condylar effusion

Answer: 3. Condylar erosion

Question 9. Joint effusion denotes.

1. Soft tissue calcifications
2. The influx of fluid into the joint
3. Crystalline structures in the joint spaces
4. Hyaline metaplasia

Answer: 2. Influx of fluid into the joint

Question 10. A jigsaw puzzle appearance is seen in.

1. Bony ankylosis
2. Fibrous ankylosis
3. Osteoarthritis
4. Rheumatoid arthritis

Answer: 2. Fibrous ankylosis

Question 11. Nonspecific condylar destruction denotes.

1. Metastatic tumors
2. Osteoma
3. Osteochondroma
4. Osteogenic sarcoma

Answer: 1. Metastatic tumors

Question 12. Bone formation is a feature of.

1. Chondrosarcoma
2. Osteogenic sarcoma
3. Malignant primary tumors
4. Malignant metastatic tumors

Answer: 2. Osteogenic sarcoma