TMD lectures Flashcards
What are the signs and symptoms of TMD?
- Tender muscles
- Tender TMJ
- Ear signs
- Limited opening
- Clicking/Locking
- Crepitus - popping and clicking sounds
What are temporomandibular disorders?
It is a cluster of musculoskeletal disorders of the mastication system that share many common symptoms.
It is characterised by jaw and face pain, temporal headaches, referred ear symptoms, limited opening, TMJ clicking and other.
It flactuates with time
What dose TMD doesn’t include?
- Iatrogenic trauma or infective causes
- Neuropathic pain - e.g. trigeminal neuralgia
- Neoplasia
- Non-parafunctional tooth wear - attrition is okay but erosion is NOT
What is the importance of the tmj ligament of the articulating disk?
The TMJ ligaments allow the disc to stay in the appropriate position and not allowing it to slip backwards or forwards
Why is the lateral surface of the articulating disk seems to sustain more damage than the media surface?
It is understood that during clenching, the joint bent medially putting a larger amount of pressure on the lateral side of the articulating disk.
Thus, through life it experiences more wear and tear and it is more likely to be perforated.
Similarly on the lateral side of the articular disk, a thickening of the TMJ ligament occurs over time
What is an important fact to distinguish when assessing the TMJ on the MRIs?
The posterior part of the articulating disk should sit at 12 o’clock to the condyle. If it it at 10 or 10.5 o’clock the joint is considered displaced.
This rule is a little be broken when talking about a steep eminence, because to to it’s steepness the condyle could see further down into the mandibular eminence thus making the joint move forward.
What is the importance of the inferior belly of the lateral ptergygoid muscle in terms of the movement to of the condyle? What does the superior belly do?
It stay active during both opening and closing thus providing a steady, regulate speed at which the condyle moves forward and back thus reducing the “rubber banding effect” of the muscle that might cause damage to the TMJ.
The superior belly acts as a disk stabilising muscle at the end of the movement.
What kind of principals would you give to a TMJ if you were to design it?
- High speed of movement
- Minimal friction
- Congruency between join surfaces
- Stability in centric
- Have minimal loading
- Able to perform pressure compensation
What are the important stages of TMJ development starting at Embryological stage all the way to adult hood?
- Around 6 week in utero - the simple reptilian join of merckel’s cartilage is created - soon to be replaced with soft tissue and the merckel’s cartilage will become the ear
- Around 12 weeks - soft tissue replace the bone - firbour tissue that will become the dist may appear
- Similar structure of TMJ at birth as in adult but the eminence and the condyle are not very developed
- In adults - the eminence is fully developed only after the deciduous dentions has been exfoliated
What is the difference between the TMJ and other synovial joints?
Normal synovial joints occur from the initial cartilage model during the embryonic development
TMJs are made up of dense fibrous tissue and arise from that rather than initial cartilage
What is the main way to compensate pressure during opening on the articulating disk?
It is mostly filled by the venous resoirvoir (pterygoid plexus) and increase the venous volume of retrodiscal tissues.
Main role of retrodiscal tissues is to perform pressure compensation
What happens to both condyles during unit lateral chewing?
The working condyle considerably shift laterally during the forwards chewing movement while the non-working condyle has a considerably less medial movement
Why does chewing, really, does not cause much damage to the teeth (talking about not chewing on rocks or other griddy things)?
It is due to the fact that during the chewing we nearly never achieve full closing of the jaws thus teeth do not contact during chewing and only contact during swallowing!
When does the most damage to the TMJ complex occurs?
It believed that the most load it taken by the contra-lateral side to the working side thus it is believed the contra-lateral side takes more damage.
This occurs due to the fact that the mandible bends thus making the pathway of the contra-lateral more irregular
When does the clikcing sound usually occurs in the TMJ that is not related to parafunction?
It occur when the disc-condyle complex go over the eminance - this is normal when click only occur during the opening
What happens if we have 2 clicks - equally spaced on the opening-closing process?
This could due to a deviation in form - a condylar or eminence bulge!
What happens if we have 2 clicks - not equally spaced on the opening-closing process?
This could be as a result of anterior disc displacement - could be due to discal ligament being loose
