Types of TMD

Question 1

Clinical features of Temporomandibular Pain Dysfunction ‘syndrome’ (muscle cause of limitation of movement)

Answer 1

• F:M = 4:1
• Most pts between 16-40 years
• Onset is usually gradual
• Pain usually one-sided, rarely severe. Typically felt in front of ear
• Typically, a dull ache is made worse by mastication
• Frequently also limitation of opening
• Clicking or crepitus in the joint
• Ultimately self-limiting
• Causes no long term damage to joint

Question 2

What is the main intracapsular cause of persistent limited mouth opening

Answer 2

Ankylosis - limited mouth opening due to fibrous or bony union of the condyle and temporal bone
Causes of ankylosis:
1. trauma: intracaspular fracture of the condyle, penetrating wounds, forceps delivery at birth
2. Infection: Otitis media/mastoiditis, osteomyelitis of the jaws, haematogenous - pyogenic arthritis
3. Arthritides: Systemic juvenile arthritis, Psoriatic arthropathy, osteoarthritis, RA
4. Neoplasms of joint: chondroma, osteochondroma, osteoma (benign tumours of the jaw)
5. Miscellaneous: synovial chondromatosis (benign)

Question 3

What is the treatment for ankylosis?

Answer 3

• Treated in a similar way regardless of cause
• All the fibrous or bony tissue causing ankylosis is removed, and interposition of temporalis muscle flap/other implant material prevents healing across the defect
• Early mobilisaiation with aggressive physiotherapy is required to prevent the ankylosis reforming

Question 4

What are some other intracapsular causes of persistent limited mouth opening

Answer 4

1. Osteoarthritis
   - Occasionally seen by chance - not a cause of significant symptoms
   - Any significant limitation of movement is likely to be from osetophytes around the joint or fragments of osteophytes
2. Neoplasia
   - Osteochondroma is the most common tumour of condyle or coronoid process
   - Osteoma and chondroma and their malignant counterparts may develop
3. Rheumatoid arthritis
   - TMJ never involved alone, and TMJ involvement is usually a late sign. 3/4 pts have clinical or RAD abnormalities of TMJ but pain and swelling are not features
   - When there are symptoms of TMJ, they are crepitus and limitation of movement with pain on clenching or chewing
   - Shape of condyle is flattened first. In severe cases, shape of condyle and glenoid fossa can be lost
4. Synoival chondromatosis
   - Multiple rounded nodules of benign cartilage grow in the joint capsule and fall into the joint space causing locking, deviation, crepitus, pain and swelling

Question 5

What are extracapsular causes of persistent limitation of movement (‘false ankylosis’)

Answer 5

1. Mechanical interference with jaw movement
   - Trauma: depressed fracture of the zygomatic bone or arch
   - Hyperplasia: developmental overgrowth of coronoid process
   - Neoplasms: osteochondroma, osteoma of the coronoid process
   - Irradiation fibrosis
   - Systemic sclerosis
2. Capsular causes
   - Trauma: periarticular fibrosis from wounds or burns
   - Infection: fibrosis from chronic periarticular suppuration
   - Joint capsule fibrosis

Question 6

What are the causes of temporary limitation of movement (trismus)

Answer 6

1. Tempromandiublar pain dysfunction ‘syndrome’
   - most common cause
2. Dislocation
   - If condyle slides over anterior articular eminence, TMJ can become fixed in open position
   - Very painful
   - Press downward and backward on or behind lower poster teeth with thumbs while standing behind pt
3. Injuries
   - E.g. unilateral or bilateral condylar neck fracture, damage to fossa, bleeding into joint (=> bloodclart => bone formation => ankylosis)
   - Any unstable mandibular fractures causes protective muscle spasm and limitation of movement
4. Infection and inflammation in or near the joint
   - Any infection or inflammation involving the muscles of mastication will lead to trismus, either making opening painful, or because oedema or swelling prevent movement
   - The main causes are surgical extraction of third molars, acute pericoronitis, and infections of dental origin in fascial spaces
   - Submasseteric abscess results in profound trismus

Question 7

What are the primary signs and symptoms of temporomandibular pain dysfunction ‘syndrome’?

Answer 7

1. Muscle and joint pain/tenderness
   - Felt during jaw movement or mastication, and on palpation
   - Pain is not severe, more of an ache or tenderness and is classically preauricular. Often poorly localised
2. Limitation of mandibular movement
   - Reduced opening and lateral excursion, associated with pain
   - Mandible deviates to the side of the pain reflecting muscle spasm
3. Joint noises
   - Usually clicks or crepitus on movement
   - Not painful

Question 8

What are the secondary signs and symptoms of temporomandibular pain dysfunction ‘syndrome’?

Answer 8

4. Bruxism
   - Pts wake up with limitation of movement and pain that slowly reduces during the day
5. Headache
   - May be misinterpreted temporalis pain, referred pain or relate to stress
6. Locking of the joint
   - Occasional
   - Indicates uncoordinated movement of the condyle, disk and muscles
7. Ear pain
   - Probably referred pain from the joint

Question 9

What is the aetiology of temporomandibular pain dysfunction ‘syndrome’?

Answer 9

• Unknown and probably multifactorial
• Stress and anxiety: recognised causes of clenching and bruising, with constant contraction of facial and masticatory muscles and pts may have other stress-associated disorders (IBS, chronic fatigue, stress headache)
• The joint is almost always normal
• Suggestions that occlusion is a primary cause have not been validated in studies
• Abnormal neuromuscular coordination, focusing areas of spasm of masticatory muscles appears to be a likely main cause

Question 10

What investigations should be done for temporomandibular pain dysfunction ‘syndrome’?

Answer 10

• Due to absence of objective signs, diagnosis is largely by exclusion
• Main function of the history and examination
  1. Organic disease/joint disease
  2. Giant cell arteritis through palpation of temporal artery
  3. Referred pain from the teeth
• Joint examination (palpation for tenderness and swelling which suggests organic disease)
• Muscle examination (identify tender areas)
• Functional examination (check movement of the mandible)
• Radiographs (exclude fluid accumulation (widening of joint space) or damage/deformity of the joint surfaces (organic disease))

Question 11

What are the principles of treatment of temporomandibular pain dysfunction ‘syndrome’?

Answer 11

• Reassurance and education
• Conservative management- reversible tx only
• Soft diet and jaw exercises
• Consider need for a splint
• Analgesics or anxiolytics in selected cases
• TMD is ultimately self-limiting and does not progress to permanent damage or degenerative arthritis later in life
• No irreversible tx should be undertaken
• There is a strong placebo effect
• Splint has diagnostic and therapeutic roles. Interfere with neuromuscular control of jaw movements and break learned habits changing the pain and joint symptoms to confirm diagnosis
  1. soft splints are easily provided for night wear to reduce bruxism
  2. hard splints are more complex to make and may either permit movement in all directions (removing occlusal guidance of jaw movement or attempt to guide the jaw to artificial correct posture)