Jaw bone pathology: TMJ diseases and disorders

TMJ anatomy

  • Condyle moves anteriorly on opening
  • Condyle moves posterior on closing
Anatomy of TMJ
  • Articular surface of bones are covered by fibrocartilage
  • Joint covered by fibrous capsule – a fibrous membrane, attaches to articular eminence, articular disc and neck of mandibular condyle
TMJ capsule
  • Articular disc is a fibrous extension of the capsule
  • Articular disc splits the joint into two synovial joint cavities, each lined by synovial membrane
  • The anterior disc attaches to the joint capsule and superior head of lateral pterygoid
  • The posterior portion attaches to mandibular fossa and is referred to as the retrodiscal tissue
  • Retrodiscal tissue is vascular and highly innervated, therefore a major contributor to pain of TMJ
Articular surfaces and disc
  • Three ligaments provide stability to the joint:
    • Temporomandibular ligament
    • Sphenomandibular ligament
    • Stylomandibular ligament
Temporomandibular ligament
Sphenomandibular ligament Stylomandibular ligament
  • TMJ muscles:
    • Temporalis – Elevation, retraction and lateral deviation of mandible
    • Lateral pterygoid – Depress, protrude and lateral deviation of mandible
    • Medial pterygoid – Elevate mandible and lateral deviation to opposite side
    • Masseter – Elevate mandible
TMJ muscles

Classification of TMJ disorders

  1. Congenital disorders:
  2. Growth disorders:
  3. Infections:
  4. Trauma:
    • Extracapsular: Condylar fracture
    • Intracapsular: Dislocation, disc displacement, ankylosis
  5. Ankylosis:
    • Bony or fibrous
    • Intracapsular (true ankylosis) or extracapsular (pseudocapsular)
  6. Dislocation:
    • Unilateral
    • Bilateral
  7. Internal derangement: Meniscal pathology
  8. Degenerative disorders:
    • Rheumatoid arthritis
    • Osteoarthritis
  9. Tumors:
    • Benign
    • Malignant
  10. Myofascial pain dysfunction syndrome (MPDS)

Symptoms associated with TMJ dysfunction:

  • CLICKING: Disk displacement.
  • LOCKING: Disk deformity + Adhesion
  • DISLOCATION: Displacement of the condyle (Single/recurrent episodes of inability to close the mouth)
Classification of temporomandibular joint disease and disorders


Epidemiology: Children (2-12 years), adolescents (12-17 years)


Classification of ankylosis


Clinical presentation:

  • Facial asymmetry (frontal view)
  • Mandibular deficiency (profile view): Birds beak
  • No or reduced TMJ motility – leading to poor oral hygiene, carious lesions, malnourished
  • Deviation of mandible to affected side in case of unilateral ankylosis
  • Malocclusion


  • Fusion of joint: “Mushroom” type bony union
  • Hyperplasia of coronoid process
  • Mandibular hypoplasia
  • Malocclusion

Objectives of management:

  • Restore mandibular growth
  • Restore function
  • Restore mouth opening
  • Restore esthetics
  • Prevent relapse


  • Aggressive resection
  • Ipsilateral/contralateral coronoidectomy
  • Lining of TMJ with temporalis fascia
  • Reconstruction of TMJ (costochondral graft)
  • Aggressive physiotherapy
  • Orthodontic and secondary orthognathic surgery
  • For long standing bilateral TMJ ankylosis:
    • Osteoarthrotomy: Condylectomy + bilateral coronoidectomy
    • Ramus osteotomy
    • Angle osteotomy
    • Total joint replacement: Indication:
      • Re-ankylosis
      • Failed autogenous graft/resorption of autograft
      • Failed previous alloplastic reconstruction
      • Severe inflammatory joint disease
      • Multiple previous surgeries

Complications of surgery:

  • Trauma to external auditory meatus
  • Damage to tympanic membrane
  • Hemorrhage – Maxillary artery, pterygoid plexus
  • Damage facial nerve
  • Paresthesia/anesthesia – Auriculotemporal nerve
  • Tear of dura mater – Middle cranial fossa
  • CSF leakage

Internal derangement

  • Abnormal location of the disk in relation to other components of the joint
  • A click sound on opening indicates a displaced meniscus
  • Late stages – intermittent locking of the jaw when the patient tries to open the mouth
  • Limited opening shows bilateral disease while deviation (towards affected side) shows unilateral disease
  • Causes of internal derangement are:
    • Microtrauma – parafunctional habits eg bruxism
    • Macrotrauma – coup and counter-coup injuries

Wilkes classification:

Wilkes classification of internal derangement
  • Stage 1 and 2: Disc displacement and reduction on opening
  • Stage 3 and 4: Disc displacement and no reduction, therefore no clicking sound
  • NB: A clicking joint does not lock and a locking joint does not click


Conservative aims:

  • Reduce pain and discomfort
  • Decrease inflammation in muscles and joints
  • Improve jaw function

Methods of conservative treatment:

  • Patient education
  • Medication
  • Physical therapy
  • Splints

Surgical treatment options:

  1. Arthrocentesis – joint aspiration
  2. Arthroscopy
  3. Arthrotomy + disc repair (eg. perforation)
  4. Arthrotomy + disc reposition
  5. Arthrotomy + discectomy
  6. Arthrotomy + discectomy + autologous graft
  7. Alloplastic joint replacement
  8. Condylotomy

Inflammatory changes in TMJ

A. Primary inflammatory changes:

  • JRA (Juvenile rheumatoid arthritis)
  • JPsA (Juvenile psoriatic arthritis)

B. Secondary inflammatory changes:

I) Direct extension of adjacent inflammatory change/infection:

  • Otitis media
  • Mastoiditis (direct extension, thrombophlebitis, hematogenous spread)
  • Osteomyelitis of temporal bone/ mandibular condyle

II) Hematological spread of infection (septicemia) resulting in septic arthritis:

  • Typhoid fever (or via otitis media/mastoiditis)
  • Peritonsillar abscess
  • Scarlet fever
  • Measles
  • Pneumonia
  • Meningitis
  • Bacterial endocarditis
  • Septic pharyngitis S
  • Sinusitis

Rheumatoid arthritis

A progressive destructive disease of bone – characterized by granuloma formation – starting in the joints of the hands and feet – spreading to affect weight bearing and minor joints

Etiology: Production of auto-antibody production against abnormal antigens in the joint tissues (rheumatoid factor)

Incidence: Temperate climates, middle aged female patients


  • Bilateral joint stiffness
  • Crepitus
  • Tenderness and swelling
  • Fever, malaise and fatigue
  • Dermal subcutaneous nodules in 25% of patients


  1. Genetic susceptibility: 65% – 80% of patients have HLA-DR4/1 & 75% have an RA specific motif in the DRB1-HV3 region of their T cells
  2. A primary exogenous arthritogen: EBV, retroviridae, parvoviridae, mycobacteria, borrelia and mycoplasma
  3. Autoimmune reaction mediated by cytokines


  • Pannus formation = proliferation of the synovial membrane
  • Condylar lipping + marginal proliferation


  • Fibrinoid necrosis in rheumatoid nodules
  • Surrounded by epithelioid histiocytes, lymphocytes and plasma cells


Juvenile chronic arthritis

Epidemiology: 70 % patients are female


  • Little/no pain
  • Limitation of movement
  • Micrognathia
  • Anterior open bite


  • Destruction of condylar process from articular surface
  • TMJ pain
  • Headache
  • Tenderness of joint & muscles (temporal, masseter & sternomastoid)


  • Chronic inflammatory arthritis in children under 5 years of age
  • Classical rash
  • Dactylitis (severe inflammation of the finger and toe joints – Sausage fingers)
  • Nail pitting
  • Onycholysis (painless detachment of the nail from the nail bed)
  • Family history



Articular crystal deposits (tophi) – due to acute and chronic bone disorders

Stages of gout progression:

  1. High uric aid levels – uric acid is building up in the blood and starting to form crystals around joints
  2. Acute gout – symptoms start to occur, causing a painful gout attack
  3. Intercritical gout – periods of remission between gout attacks
  4. Chronic gout – gout pain is frequent and tophi form in joints



A disorder of movable joints – deterioration and abrasion of articular cartilage with new bone formation at the joint surface.


  • Primary: Insidious age change
  • Secondary:
    • Secondary to repetitive overload of the joint
    • Underlying systemic disease eg diabetes


  • Heberden’s nodes (osteophytes develop in phalanges)
  • Crepitation sounds from joints
  • Restricted/normal mouth opening capacity (normal is 3 finger breadth)
  • Pain/no pain from joint area and mastication muscles


  • Condylar erosion
  • Eburnation
  • Subchondral sclerosis
  • Flattening of articular eminence
  • Osteophytes (bone projections)


  • Physical therapy
  • Pulsed electrical stimulation
  • Topical ointments
  • Supplements
  • Steroid injections – Corticosteroids only relieve pain but does not treat, therefore damaging the joint more
  • Hyaluronic acid injections
  • Acupuncture


TMJ pain dysfunction syndrome

AKA Myofacial pain dysfunction syndrome (MPDS)

A multifactorial syndrome of neurological, psychological and dental origins.

Etiology: Bruxism, masticatory muscle spasm, emotional status

Clinical: Laskin’s 4 signs:

  1. Unilateral pain – in front of the ear, over the joint
  2. Pain in related facial, jaw and neck muscles
  3. Associated limitation & deviation of jaw opening
  4. Clicking or popping sound in the joint

Negative characteristics:

  1. Absence of clinical, radiographic or biochemical evidence of organic changes in TMJ
  2. Lack of tenderness in TMJ area when palpated via EAM


  • Detailed examination
  • Panoramic tomography
  • Conservative approach: Occlusal splint, psychologist referral, relaxation techniques or low dose diazepam
  • Botox for masseter, temporalis and pterygoids
  • Soft diet, avoid excessive gum chewing
  • Gentle massage at TMJ area, warm and cold compresses


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