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DENT 322 - Image Interpretation > TMJ > Flashcards

TMJ Flashcards

1
Q

5 indications for TMJ imaging

A
  • Osseous lesion of abnormality
  • Trauma
  • Dysfunction, limitation of movement
  • Changing occlusion
  • Infection

NOTE: Should always follow a clinical exam

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2
Q

3 contraindications for TMJ imaging

A
  • Clicking in the absence of other symptoms such as pain or limitation of opening
  • Pre-orthodontic treatment in children and adolescents
  • Baseline record
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3
Q

Usefulness of panoramic rx for TMJ

A

Useful for fractures of the ramus and to evaluate mandibular asymmetry

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4
Q

4 ways the panoramic radiograph is not so useful in imaging the TMJ

A
  • Mandible is in protrusion because the patient bites on a bite-block –> cannot evaluate condylar position
  • Base of skull and zygomatic arch obscure the condyle at the superior aspect
  • Medial pole of the condyle is projected superiorly
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5
Q

4 shapes of the madibular condyle that are normal variants in the coronal plane

A
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6
Q

Average dimensions of the mandibular condyle

A
  • 20 mm mediolaterally
  • 10 mm anteroposteriorly
  • 100 mm from center of R to center of L
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7
Q

Angle of the long axis of the condyle with the coronal plane

A

10 - 30o (average 15o)

Lateral view optimally achieved when x-rays are directed along the long axis of the condyle

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8
Q

Depth of fossa

A

7 mm

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9
Q

Angulation of highest point of fossa to lowest point of articular eminence

A

40o

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10
Q

Dimensions of the disk

A
  • Thin central part = 1 mm (where movement occurs)
  • Anterior band = 2 mm
  • Posterior band = 3 mm (NOTE: superior to condyle)
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11
Q

2 joint compartments

A
  • Superior compartment (superior joint space)
  • Inferior compartment (inferior joint space)
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12
Q

What is the relationship between the two joint compartments

A

The two do not normally communicate. Only rarely communicate when the disk is perforated

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13
Q

Radiographic appearance of the joint space

A

Crescent shaped radiolucency on plain films between the superior aspect of the condyle and the glenoid fossa that contains the soft tissues of the joint:

  • Disk and posterior attachment
  • Collagenous connective tissue covering the articular surgace (0.1 - 1 mm thick)
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14
Q

3 indications for CBCT of TMJ

A
  • Evaluation of bony structures
  • Evaluation of condulat position from the medial pole to the lateral pole
  • Evaluation of joint spaces
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15
Q

2 disadvantages of CBCT for TMJ imaging

A
  • Non-dynamic
  • No soft tissues imaging
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16
Q

3 movements of the condyles

A
  • Rotation in the lower joint space
  • Translation in the upper joint space
  • During translation, the condyle reaches the height of the articular eminence or slightly anterior
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17
Q

Condition associated with retruded condyle

A

Anteriorly displaced disk

NOTE: Asymptomatic patients may not have this

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18
Q

Condition associated with protruded condyle

A

Juvenile rheumatoid arthritis

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19
Q

Condition associated with inferior condylar position

A

Bloor or fluid in the joint

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20
Q

Condition associated with superior condylar position

A

Osteoarthritis (loss, perforation or displacement of soft tissues)

21
Q

Purpose of arthrography

A

To image the position and morphology of the disk under sterile conditions

22
Q

Describe the process of arthrography

A
  1. Injection of radiopaque contrast agent (iodine) into the inferior joint space or inferior and superior joint spaces
  2. Contrast agent in the joint spaces outlines the disk and its anterior and posterior attachments
23
Q

When is arthrography indicated

A

In case of suspected internal derangements, particularly is surgery is contemplated

24
Q

Most common abnormality when imaging patients with TMJ disorder

A

Disk displacement

25
Q

4 symptoms of internal derangement of TMJ

A
  • Pain in TMJ region
  • Clicking (but not treatment necessary if asymptomatic)
  • Limitation of movement with possible deviation
  • Tenderness of muscles of mastication upon palpation
    • Masseter
    • Temporalis
    • Medial and lateral pterygoids
26
Q

Describe a normal arthrogram

A
  • Posterior recesses of the upper and lower joint spaes are large when the mouth is opened
  • The anterior recess of the lower joint space follows the outline of the condule and articular eminence
27
Q

3 characteristics of anteriorly placed disk with reduction

A
  • Early phase of spectrum of internal derangement
  • Reciprocal clicking (on opening and closing)
    • NOTE: absence of clicking does not indicate a normal joint
  • Deviation in condylar path during opening and closing
28
Q

Describe the arthrogram of an anteriorly displaced disk with reduction

A
  • Close: The anterior recesses of the upper and lower joint spaces extend anteriorly. This is ABNORMAL, the disk is anteriorly displaced
  • Open: The posterior recesses of the upper and lower joint spaces are large. The anterior recesses of the upper and lower joint spaces do not extend anteriorly. This is NORMAL, the disk reduces (disk recaptured upon opening)
29
Q

5 characteristics of anteriorly displaced disk without reduction

A
  • Often preceded by reduction so it is a progression of internal derangement
  • Closed lock
  • Perforations of the disk are common
  • Limitation of opening, reduced translation, deviatoin to the affected side
  • Pain upon opening
30
Q

Describe the arthrogram of an anteriorly displaced disk without reduction

A
  • Close: The anterior recesses of the upper and lower joint spaces extend anteriorly. This is ABNORMAL, the disk is anteriorly displaced.
  • Open: The posterior recesses of the lower joint spaces does not fill with contract. The anterior recesses of the upper and lower joint space continue to extend anteriorly. This is ABNORMAL. The disk does not reduced
31
Q

4 indications for MRI of TMJ

A
  • Evaluation of internal derangement
  • More accurate and less invasive than arthrography to evaluate disk position
  • Evaluation of join effusion and inflammatory changes (T2)
  • Evaluation of damage to retrodiskal tissue in cases of trauma
32
Q

Describe finding of MRI for anteriorly displaced disk with reduction

A

Condyle is displaced posteriorly at rest

33
Q

Describe the finding of MRI for anteriorly displaced disk without reduction

A

Anterior and posterior bands are anteriorly displaced even upon opening (does not correct)

34
Q

3 characteristics of condylar hyperplasia

A
  • One condyle larger than the other. Ramus can be affected
  • Bowing of the inferior border
  • Asymmetry of the face, deviation to the unaffected side
35
Q

4 characteristics of condylar hypoplasia

A
  • One condyle smaller than the other. Ramus can be affected
  • Deep antegonial notch
  • Asymmetry of the face, deviation to the affected side
  • Bilateral hypoplasia in mandibulofacial dysostosis: Trecher-Collins’ syndrome
36
Q

Describe the clinical findings of a condylar fracture

A

Mandible is normally positioned upon closing but deviates upon opening to the side of the fracture

37
Q

2 potential causes for bifid condyle

A
  • Possible developmental abnormality
  • Sometimes due to condylar fracture
38
Q

Describe the radiographic appearance of bifid condyle

A
  • Depression in the center of the superior surgce of the condyle
  • Double heads
39
Q

Most likely cause of size difference between R and L rami

A

Rotation of the head

40
Q

Define osteoarthritis

A

Deterioration of the soft tissue covering the articular surgaces and exposure of the underlying bone. 85% of population affected after age 70

41
Q

TMJ symptoms of osteoarthritis (5)

A
  • Pain
  • Deviation
  • Crepitus
  • Stiffness
  • Limited opening
42
Q

2 TMJ conditions associated with osteoarthritis

A
  • Anteriorly displaced disk without reduction
  • Perforated disk
43
Q

6 radiographic findings of degenerative joint disease (i.e. such as osteoarthritis) in TMJ

A
  • Narrowing or loss of joint space
  • Resorption of the anterior/superior surface of the condyle
  • Resorption of the anterior surface of the fossa. Eminence becomes glattened and fossa enlarges
  • Subchondral sclerosis
  • Osteophytes (bony spurs) form on anterior/superior surface of condyle
  • Subchondral cysts (small areas of degeneraiton below the articular surface; Ely cysts)
44
Q

Cause of ankylosis of TMJ

A

Previous trauma or infection

NOTE: Usually in young patients <15 yrs

45
Q

3 characteristics of ankylosis of TMJ

A
  • When ankylosis occurs before the end of the growth of the mandible, the ankylosed side is underdeveloped
  • Prominent antegonial notch
  • Bud of 3rd molar develops higher on the ankylosed side
46
Q

4 benign tumors of bone or cartilage in TMJ

A
  • Osteoma (bone growth from cortical bone)
  • Osteochondroma (bone and cartilage growth from cancellous bone)
  • Chondroma (cartilage growth from cancellous bone)
  • Synovial chondromatosis (leads to calcification of joint)

NOTE: rare

47
Q

4 consequences of benign tumors of TMJ

A
  • Facial asymmetry
  • Malocclusion
  • Limitation of opening
  • Pain
48
Q

5 tumors of bone or cartilage that may affect TMJ

A
  • Chondrosarcoma
  • Osteosarcoma
  • Synovial sarcoma
  • Fibrosarcoma of the joint capsule
  • Metastases

NOTE: extremely rare

49
Q

4 consequences of malignant tumors on TMJ

A
  • Facial asymmetry
  • Malocclusion
  • Limitation of opening
  • Pain

DENT 322 - Image Interpretation (12 decks)

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