TMJ anatomy
- Condyle moves anteriorly on opening
- Condyle moves posterior on closing
- 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
- 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
- Three ligaments provide stability to the joint:
- 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
Classification of TMJ disorders
- Congenital disorders:
- Growth disorders:
- Condylar hyperplasia (uni/bi)
- Coronoid hyperplasia (TMJ ankylosis)
- Infections:
- Primary:
- Secondary:
- Trauma:
- Extracapsular: Condylar fracture
- Intracapsular: Dislocation, disc displacement, ankylosis
- Ankylosis:
- Bony or fibrous
- Intracapsular (true ankylosis) or extracapsular (pseudocapsular)
- Dislocation:
- Unilateral
- Bilateral
- Internal derangement: Meniscal pathology
- Degenerative disorders:
- Rheumatoid arthritis
- Osteoarthritis
- Tumors:
- Benign
- Malignant
- 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)
Ankylosis
Epidemiology: Children (2-12 years), adolescents (12-17 years)
Classification:
Causes:
- Trauma: Intracapsular fracture, penetrating wounds (gunshot), forceps delivery
- Chronic infection
- Rheumatoid arthritis
- Cancrum oris
- Radiotherapy: Osteoradionecrosis
- Burns
- Tumors
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
Radiology:
- 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
Management:
- 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:
- 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
Management:
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:
- Arthrocentesis – joint aspiration
- Arthroscopy
- Arthrotomy + disc repair (eg. perforation)
- Arthrotomy + disc reposition
- Arthrotomy + discectomy
- Arthrotomy + discectomy + autologous graft
- Alloplastic joint replacement
- 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
Clinical:
- Bilateral joint stiffness
- Crepitus
- Tenderness and swelling
- Fever, malaise and fatigue
- Dermal subcutaneous nodules in 25% of patients
Pathology:
- 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
- A primary exogenous arthritogen: EBV, retroviridae, parvoviridae, mycobacteria, borrelia and mycoplasma
- Autoimmune reaction mediated by cytokines
Radiology:
- Pannus formation = proliferation of the synovial membrane
- Condylar lipping + marginal proliferation
Histology:
- Fibrinoid necrosis in rheumatoid nodules
- Surrounded by epithelioid histiocytes, lymphocytes and plasma cells
Juvenile chronic arthritis
Epidemiology: 70 % patients are female
Clinical:
- Little/no pain
- Limitation of movement
- Micrognathia
- Anterior open bite
I) JRA:
- Destruction of condylar process from articular surface
- TMJ pain
- Headache
- Tenderness of joint & muscles (temporal, masseter & sternomastoid)
II) JPsA:
- 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
Gout
Articular crystal deposits (tophi) – due to acute and chronic bone disorders
Stages of gout progression:
- High uric aid levels – uric acid is building up in the blood and starting to form crystals around joints
- Acute gout – symptoms start to occur, causing a painful gout attack
- Intercritical gout – periods of remission between gout attacks
- Chronic gout – gout pain is frequent and tophi form in joints
Osteoarthritis
A disorder of movable joints – deterioration and abrasion of articular cartilage with new bone formation at the joint surface.
Subtypes:
- Primary: Insidious age change
- Secondary:
- Secondary to repetitive overload of the joint
- Underlying systemic disease eg diabetes
Clinical:
- 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
Radiology:
- Condylar erosion
- Eburnation
- Subchondral sclerosis
- Flattening of articular eminence
- Osteophytes (bone projections)
Management:
- 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:
- Unilateral pain – in front of the ear, over the joint
- Pain in related facial, jaw and neck muscles
- Associated limitation & deviation of jaw opening
- Clicking or popping sound in the joint
Negative characteristics:
- Absence of clinical, radiographic or biochemical evidence of organic changes in TMJ
- Lack of tenderness in TMJ area when palpated via EAM
Management:
- 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
DentMistry 
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