TMJ wilkinson

Question 1

What are SIX signs/symptoms of TMD?

Answer 1

• Tender muscles
• Tender TMJ
• Ear signs (pain, blockage)
• Limited opening (reflex opening inhibition due to inflammed TMJ)
• Clicking/locking
• Crepitus (hard and soft)

Question 2

What is ONE biological reason why women might present for treatment of pain 3x more than men?

Answer 2

Oestrogen potentiates pain at a spinal level (peak pain seen in child bearing years)

Question 3

What are FIVE causes of jaw pain that TMD is NOT considered?

Answer 3

• Iatrogenic trauma
• Infection
• Neuropathic pain (trigeminal neuralgia, migraine, atypical odontalgia)
• Neoplasia
• Non-parafunctional tooth wear

Question 4

What was atypical odontalgia previously known as?

Answer 4

Atypical odontalgia was previous known as phantom tooth pain

Question 5

Why might an impression of the mandible be less accurate when the patient is at max opening?

Answer 5

The mandible can flex laterally up to 2mm during max opening.

Question 6

Which ligament acts as the posterior restraint (prevents condyle moving too posteriorly)

Answer 6

Temporomandibular ligament (aka. lateral ligament)

Question 7

What is the reasoning for wanting to change centric relation from most posterior to most anterior position?

Answer 7

We want centric relation to coincide with a physiological (ie. not pathological) position of the condyle. Most posterior is stretching the TM ligament to the max = not physiological, so most anterior makes sense.
NOTE: definition includes condition that disk is in place.

Question 8

Which is thinner, the anterior thick or posterior thick portion of the articular disk of the TMJ? Why?

Answer 8

• Anterior thick (in adults)

- Due to loading wear and tear and lack of regenerative ability (low blood supply)

Question 9

Which dictates the position of the other: TMJ vs. teeth. What is ONE implication?

Answer 9

Teeth dictate the position of the TMJ. Implications for ortho.

Question 10

What is the main function of the upper head of the lateral pterygoid?

Answer 10

It contracts to produce a stiff ‘leather strap’ to keep the foot of the articular disk in line with the condyle during final/slow closing (it is attached to both).

Question 11

What is the main role of the TMJ?

Answer 11

To aid in mastication (gaining nutrients)

Question 12

What are SIX aspects of an ideal TMJ?

Answer 12

• High speed movement
• Minimal friction
• Minimal loading
• Congruency
• Stability in centric
• Pressure compensation

Question 13

Why do ear symptoms occur during TMD?

Answer 13

Neural confusion between TMJ and ear (not due to residual ear elements in TMJ)

Question 14

How does the articular eminence differ from birth to adulthood?

Answer 14

It begins fairly flat at birth and becomes curved towards adulthood (influenced by position of teeth)

Question 15

What is so special about the articular surface of the TMJ and sternoclavicular joint vs. the rest of the body?

Answer 15

TMJ and sternoclavicular joint articular surfaces are made of dense fibrous tissue, the rest of the body’s articular surfaces are hyaline cartilage.

Question 16

What are THREE differences between hyaline cartilage and fibrous tissue?

Answer 16

• Glassy (hyaline) vs. dense white (fibrous)
• Good for compressive and torsion (hyaline), better for shearing than compressive (fibrous)
• Some regenerative ability (hyaline), adapts in response to loading (fibrous)

Question 17

What are the SIX layers of a fibrous joint? (name some functions where necessary)

Answer 17

1. CT lining
2. Mesenchymal layer (contain stem cells that aid in adaptation through production of fibrous cartilage)
3. Transitional layer (for fine tuning during different stages of dentition. Not present in elderly)
4. Fibrous cartilage (articular surface)
5. Compact bone (condyle)
6. Spongy bone (condyle)

Question 18

Why does the TMJ need pressure compensation and how is this acheived?

Answer 18

• Condyle movement in/out of the mandibular fossa creates a piston effect producing pressure
• Compensated via retrodiscal tissue taking its place, eliminating piston pressure

Question 19

Superficial vs. Deep masseter:

• Location
• Roles
• Marathon vs. sprinter?

Answer 19

Masseter muscle is a sprinter. Sustained contraction may result in muscle soreness.
Superficial
- Force generator for mastication
- Placed over dentition
Deep
- Stabiliser
- Placed over TMJ

Question 20

When does the masseter activate vs. temporalis?

Answer 20

Temporalis activates quite early, with masseter only coming on just before bolus is pierced.

Question 21

Where can pain from the temporalis present as?

Answer 21

• Headache (it runs high up the skull)

- Pain behind the eye (anterior portion goes deep near eye)

Question 22

What reflex is the digastric muscle prominent in?

Answer 22

Unloading reflex (tenses when biting into something that might break, activates after the break)
NOTE: it depresses mandible when hyoid is held in place

Question 23

How does condyle movement at the working (chewing) side and non-working side differ?

Answer 23

• Working side moves posterior to a point behind the original position and moves anterio-superiorly against the eminence
• Non-working side keeps moving anterior after working side starts moving posterior

-> Net effect: jaw swings laterally towards working side and moves back to intercuspal to attack bolus.

Question 24

What bony structure takes significantly more load than the neighbouring bone during chewing?

Answer 24

Articular eminence
(mandibular fossa takes very little load. As a result, eminence is very thick, while superior portion of fossa is very thin.)

Question 25

When chewing, which condyle takes the most load: ipsilateral or contralateral? How might this be relevant clinically?

Answer 25

Contralateral, because the bolus is taking most of the load at the ipsilateral side. Clinically, someone may be more comfortable chewing on their sore side vs. good side.

Question 26

What is unique about loading the 3rd molars vs. areas more anterior in the mouth?

Answer 26

It produces an unloading effect on the TMJ, theoretically predisposing it to injury.

Question 27

What are the names of the THREE main click patterns of TMJ dysfunction? Are the clicks painful or painless? Out of the three, which most likely requires treatment?

Answer 27

Eminence, Deviation in form, Anterior displacement. - Clicks are usually painless. - Anterior displacement, because with reduction could progress to without reduction and jaw will then have a 'locked' feeling as condyle is unable to reclaim disk.

Question 28

Eminence: - Where does the click/s occur? - Description of what's happening - Cause - Treatment

Answer 28

- Click on wide opening, no click on closing - Click due to condyle moving past tip of eminence - Cause: Starts due to clicking habit - Tmt: Stop the habit (dont open too wide e.g. during yawning, dont chin sit ie. moves condyle anteriorly)

Question 29

Deviation in form: - Where does the click/s occur? - Description of what's happening - Cause - Treatment

Answer 29

- Click usually on middle third with reciprocal click on closing - Click due to thickening of fibrous portion of joint in response to biomechanical loading - Cause: Pencil biting or clenching - Tmt: Stop the habit and hopefully deviation in form will decrease

Question 30

Anterior displacement: - Where does the click/s occur? - Description of what's happening - Cause - Treatment

Answer 30

- Click anywhere on opening (depends on severity of anterior disk displacement), click on final closing (at intercuspal position) - Click when condyle moves back under disk and click when disk slips off to the front of condyle - Cause: Natural variation, macro/microtrauma, increased friction (disk can get gluey on eminence) - Tmt: ??

Question 31

What are TWO main differences between diurnal (daytime) and nocturnal parafunction?

Answer 31

- Diurnal is light forces, nocturnal is heavy forces | - Diurnal associated with oral habits

Question 32

Histologically, what position would you usually find the junction between retrodiscal tissue and thick portion of the disk?

Answer 32

12 o'clock