radiographs of the TMJ Flashcards
DJD / osteoarthritis
1) occurs when the load on the TMJ exceeds the body’s ability to withstand it
2) will show as flattening and discontinuity of cortex
3) when load decreases, the cortex will start to close again, but will not become round again
shape of TMj
1) healthy
- round
- intact cortex
2) DJD active
- shape flattened
- cortex interrupted
3) inactive DJD
- shape flattened
- cortex intact / sclerotic
DJD occlusal changes
1) posteriors may wear on the occlusals to compensate
- the rest of the teeth will remain in contact
2) teeth may not be able to compensate eventually
- anterior open bite develops (less common)
with active DJD
1) avoid orthodontics
- why arrange occlusion when it will open up afterwards
2) esthetic work
- if they develop anterior open bite after veeners, they will be dissatisfied
with active DJD caution with distalmost teeth
1) between crown prep and delivery
- occlusal clearance may collapse rapidly
- temporary may break repeatedly
2) DO composite may fracture or dislodge repeatedly
3) Implant may fail due to overloading
if DO has to be done
1) tell them it may fracture repeatedly
2) not as much of a concern on non-distalmost teeth
With Inactive Degenerative Joint
Disease
1) treat it like a
normal/healthy joint
* Except remember that DJD could always re-activate
* If they respond to stressors with DJD, it could happen again
2) let them know there is some risk bite may shift sometime in the future
individual slices
1) middle upper
- birds eye view
2) right and left coronal view in corns
3) right and left sagittal view
- 6 adjacent slices each
- show progressively deeper slices
4) Allow detection of much smaller (earlier) cortical interruptions than Pano
- By the time a cortical interruption shows on a pano (moderate size), it’s often past the point of opportunity for
meaningful dental intervention
why cant a pano detect small breaks
1) x-ray beam has to pass through lots of healthy cortex
2) cannot be detected if there is more healthy cortex relative to interrupted cortex
individual slices avoid obscuring by other structures
1) The superiormost 10% is what gets obscured in a PANO
- because it passes through the socket
2) unfortunately, this is the only area where cortical interruption occurs
Non-distorted imaging (while in maximum intercuspation bite) allows
assessment of position of the TMJ condyle
- cannot be visualized on a pano because it takes a round skull and flattens it (distorted)
When to Re-Scan Active DJD To
Determine If It Has Become Inactive
1) At least 6-12 months after the prior scan
* Recortication takes 6 months to show radiographically
2) needs to be done before othodontics are done
Between scans:
Habit reduction
1) First 1-2 weeks:
* Oral Behaviors Checklist (ask WHY?)
* Hourly reminders
* Determine causes
2) Subsequently
* Address causes
* Periodic timers to check on progress
The longer the wait, the less
- Radiation
- Feedback on progress
round condyle
1) looks like a thumb with a clear cortical border (thumbnail)
2) should be centered in fossa
sclerosis
1) thickening of cortex where there is pressure
2) implies the joint has been stressed and was able to close the interruption
mild DJD
1) continuous cortex
2) mild flattening
pressure =
force/area
moderate DJD inactive
1) moderate flattening
2) may or may not have discontinuous cortex
3) osteophytes visible (look like bird beaks in every slice)
- span the whole area
moderate DJD, active
1) subchondral cysts
- areas of erosion
2) interrupted cortex
3) osteophytes do not go away
- so this is a sign it was previously inactive
severe DJD
1) severe flattening
2) subchondral cysts
3) osteophyte may be broken off
4) bony ligament
3) irregular surface
severe rheumatoid arthritis
1) looks similar to DJD
2) body attacks the joint
3) should already have a systemic diagnosis, so we can tell it is caused by mid-late stage
- ask them if they have OTHER joint pain if they do not know
idiopathic condylar resorption
1) flattening of TMJ with no clear overload, joint degeneration, etc
2) no cause can be determined
3) likely to develop anterior open bite
