Temporomandibular Dysfunction

Question 1

Where does the masseter muscle originate and insert?

Answer 1

Originates from the zygomatic buttress (zygomatic arch) and the angle of the mandible
Inserts on the under surface of the zygomatic arch

Question 2

Where does the temporalis muscle originate and insert?

Answer 2

Originates in the temporal fossa
Inserts on the coronoid process

Question 3

Where does the medial pterygoid muscle originate and insert?

Answer 3

Originates on the medial side of the lateral pterygoid plate
Inserts on the medial side of the angle of the mandible

Question 4

Where does the lateral pterygoid muscle insert and originate?

Answer 4

2 origins- one from the base of the skull and the other from the lateral surface of the lateral pterygoid plate
Inserts onto the pterygoid fovea which is just below the condyle of the mandible but some of its fibres go into the capsule and join onto the articulator disc

Question 5

What is the blood supply to the TMJ?

Answer 5

Deep auricular artery (branch of 1st part of the maxillary artery)

Question 6

What is the nerve supply to the TMJ?

Answer 6

Auriculotemporal (gives sensation to parts of external auditory meatus)
Masseteric
Posterior (deep) temporal nerve

Question 7

What is anterior disc displacement with reduction?

Answer 7

The articulator disc can return to its normal place
Slips in front of the condyle but is able to slip back into its correct place

Question 8

What is articulator disc displacement without reduction?

Answer 8

Articulator disc slips in front of the condyle and is not able to slip back therefore is in front of the condyle permanently

Question 9

What are the causes of TMD?

Answer 9

Myofacial pain (problems related to muscles)
Disc displacement
Degenerative disease
–localised (osteoarthritis- wear of the joint)
–generalised (systemic)- rheumatoid arthritis
Chronic recurrent dislocation
Ankylosis - Condyle is fused to base of skull (rare)
Hyperplasia
Neoplasia
Infection

Question 10

What is condylar hyperplasia?

Answer 10

One condyle grows more than the other
Causes facial asymmetry
Can cause TMD

Question 11

What is the pathogenesis of TMD?

Answer 11

Inflammation of muscles of mastication or TMJ secondary to parafunctional habits
Trauma, either directly to the joint or indirectly (i.e. mouth open for long periods of time)
Stress (clenching teeth)
Psychogenic

Question 12

What are the intraoral signs of parafunctional habits?

Answer 12

Cheek biting
Linea alba- white line on inside of cheek following the occlusal plane
Tongue scalloping
Occlusal non-carious tooth surface loss (attrition) usually from grinding (rubbing teeth together) not clenching (just keeping the teeth together)

Question 13

What special investigations can be done when examining possible TMD?

Answer 13

Not usually required but if there is a suspicion of pathology they can be justified
-OPT
-CT/CBCT specifically of the joints (not done routinely)
-MRI- only if suspecting the disc is out of place
-Transcranial view (TMJ view)
-Nuclear imaging (Technetium 99)
-Arthrography- injecting something into the joint and then taking an image
-Ultrasound

Question 14

What is Nuclear Imaging?

Answer 14

Radioactive isotope can be injected into the patients if you suspect conditions like hyperplasia
If you have overgrowth on any part of the body, injecting the technecium-99 it will be taken up more in the areas of increased cellular activity
The machine then picks up the hot spots of where increased cellular activity is occurring

Question 15

What are the common clinical features of TMD?

Answer 15

More commonly females
18-30 years most commonly
Intermittent pain of several months or years duration
Muscle/joint/ear pain, particularly on wakening
Trismus/locking
Clicking/popping noises
Headaches
Crepitus (indicates late degenerative changes)

Question 16

What are some of the differential diagnosis for TMD?

Answer 16

Dental pain
Sinusitis
Ear pathology
Salivary Gland pathology
Referred neck pain
Headache
Atypical facial pain
Trigeminal Neuralgia
Condylar fracture
Temporal arteritis

Question 17

What is temporal arteritis?
Treatment?

Answer 17

Severe inflammation of the artery
If it is not treated, can result in blindness
Treatment
–high dose steroids and then biopsy

Question 18

What non pharmacological treatment can be provided for TMD?

Answer 18

Patient education
Counselling (chronic condition)
Jaw exercises (physiotherapy)
Gumshield

Question 19

What pharmacological treatment can be provided for TMD?

Answer 19

NSAIDs
Muscle relaxants
Tricyclic antidepressants
Botox
–paralyses the muscle and can reduce clenching habit (not 1st line treatment, used when they have failed)
Steroids
–reduce inflammation within the joint and muscles

Question 20

What counselling can be provided for a patient suffering from TMD?

Answer 20

Reassurance
Soft diet
No wide opening
No chewing gum
Cut food into small pieces
Stop parafunctional habits e.g. nail biting, grinding
Support mouth on opening e.g. yawning

Question 21

What physical therapy can be provided for a patient suffering from TMD?

Answer 21

Physiotherapy
Massage/heat
Acupuncture
Relaxation techniques
TENS (transcutaneous electronic nerve stimulation) - relaxes muscles
Hypnotherapy and CBT
Splints (bite raising appliances, anterior repositioning splint)

Question 22

What do bite raising appliances do?

Answer 22

Stabilise the occlusion and improve the function of the masticatory muscles, thereby decreasing abnormal activity. They also protect the teeth in cases of tooth grinding

Question 23

What types of TMJ surgery can be performed for TMD?

Answer 23

Surgery is not routinely carried out as if you don’t deal with the underlying cause e.g. clenching habit then surgery is only a temporary fix
Arthrocentesis
Arthroscopy
Disc-repositioning surgery
Disc repair/removal
High condylar shape
Total joint replacement

Question 24

What causes the joint to click in TMJ?

Answer 24

Due to lack of coordinated movement between the condyle and the articular disc
Upon opening as the condyle moves forward and it slides past the articular eminence that disc should move with it but what happens in disc displacement is because of the increased pressure in the joint that disc slips in front of the joint while the mouth is closed so when they come to open their mouth the first part is normal but then when they go to open their mouth full the disc is trapped so patient feels pain or limited mouth opening until they hear a click/pop where the disc is moving back to where it should be