Dent 356-11 Diseases of the Temporomandibular Joint

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Dent 356-11Diseases of the Temporomandibular
Joint

• Structural Aspects
• Developmental Disorders
• Inflammatory Disorders
• Osteoarthrosis
• Functional Disorders
• Loose Bodies
• Neoplasms
• Age Changes in the Jaws TMJ
• Trismus Dislocation
• Dr. Huda Hammad

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Structural Aspects of the TMJ

• Components of the TMJ
• Mandibular condyle (articular surface)
• Articular fossa
• Articular disc

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Structural Aspects of the TMJ

• The articular surface of the mandibular condyle
• consists of 3 cell zones during growth
• articular zone, dense fbrous tissue covering
  surface.
• proliferative or cellular zone, main growth
  center.
• hypertrophic zone, endochondral ossification.

• In adults, the proliferative zone is reduced to a
  narrow band.
• The hypertrophic zone is replaced by
  fibrocartilage.
• With advancing age, the articular surface becomes
  increasingly fibrous.
• Remodeling of the articular surface takes place
  throughout life to compensate for occlusal wear
  or loss of teeth.

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Structural Aspects of the TMJ

• 2. The articular fossa
• Covered by a thin layer of fibrous issue which
  thickens over the articular eminence.
• Pathological changes involve the surface of the
  fossa much less frequently than the condyle.

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Structural Aspects of the TMJ

• 3. The articular disc
• Composed of fibrocartilage.
• The disc components result in a viscoelastic
  structure important in absorbing stress.
• Arranged in
• anterior band
• intermediate zone
• posterior band
• retrodiscal tissues.

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Structural Aspects of the TMJ

• The lateral pterygoid muscle is attached to the
  medial part of the anterior band.

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Structural Aspects of the TMJ

• The lateral part of the anterior band is related
  to masseter and temporalis muscles.

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Structural Aspects of the TMJ

• The posterior attachment of the disc is formed by
  the retrodiscal tissues, a loosely organized
  meshwork of collagen and elastic fibers, fat,
  numerous blood vessels and nerves.
• It connects the posterior band to the temporal
  bone, auditory meatus, and condyle.

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Developmental DisordersCondylar Aplasia

• Extremely rare.
• May be unilateral or bilateral.
• Most reported cases associated with other facial
  anomalies.

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Developmental DisordersCondylar Hypoplasia

• Congenital unknown causes, unilateral or
  bilateral.
• Acquired trauma (birth injury or fracture),
  radiation, or infection usually extension from
  middle ear.

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Developmental DisordersCondylar Hypoplasia

• The earlier the damage, the more severe is the
  resulting facial deformity.

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Developmental Disorders Condylar Hyperplasia

• Rare.
• Self-limiting.
• Unknown cause.
• Generally unilateral.

• Facial asymmetry and deviation of mandible to
  opposite side and malocclusion.
• Becomes apparent during 2nd decade of life.

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Inflammatory DisordersTraumatic Arthritis

• Damage to joint following acute trauma may lead
  to traumatic arthritis or hemarthrosis.
• Usually resolves if tissue damage is not severe.
• Otherwise, scar tissue formation may lead to
  ankylosis.

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Inflammatory DisordersInfective Arthritis

• Rare.
• Infection may reach TMJ by
• Direct spread from adjacent focus, e.g. middle
  ear or surrounding cellulitis.
• Hematogenous spread from distant focus.
• Facial trauma.
• Staphylococcus aureus most common isolate.
• TMJ may be involved in patients with infective
  polyarthritis, e.g. gonococcal or viral arthritis.

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Inflammatory DisordersInfective Arthritis

• Clinical Features
• Pain.
• Trismus.
• Deviation on opening.
• Signs of acute infection.

• Complications
• Fibrous or bony ankylosis.

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Inflammatory DisordersRheumatoid Arthritis

• Non-organ specific autoimmune disease with
  articular and extra-articular manifestations.
• Commonly begins in early adult life.
• Affects women more frequently than men.
• Systemic distribution in which joint involvement
  is the main feature.
• Other features include
• Anemia.
• Weight loss.
• Subcutaneous nodules over bony prominences and
  joints.
• 10 of patients may show features of Sjögren
  syndrome.

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Inflammatory DisordersRheumatoid Arthritis

• Smaller joints are usually affected, particularly
  in the hand.
• Distribution tends to be symmetrical.
• TMJs involved in 20-70 of cases, although few
  complain of TMJ pain.
• When symptomatic, TMJ involvement presents as
• Limitation of opening.
• Stiffness.
• Crepitus.
• Referred pain.
• Tenderness on biting.
• Severe disability is unusual.

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Inflammatory DisordersRheumatoid Arthritis

• Joint involvement starts as synovitis with
  intense infiltration of lymphocytes and plasma
  cells.
• Inflamed synovial tissues proliferate and
  synovial membrane becomes hyperplastic.

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Inflammatory DisordersRheumatoid Arthritis

• Synovial membrane forms folds which extend over
  articular surfaces, clothing them in a vascular
  pannus.

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Inflammatory DisordersRheumatoid Arthritis

• The pannus causes resorption of articular
  surfaces, which may extend into adjacent bone.
• Articular surfaces may become very irregular and
  fibrous ankylosis may result, either in the lower
  joint compartment or with total destruction of
  articular disc and complete ankylosis.

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Inflammatory DisordersRheumatoid Arthritis

• Erosion of condyle may be seen radiographically.
• This is a typical MRI of rheumatoid arthritis.
  The top of the condyle is ragged (red arrow) and
  the disc is displaced forward.
• Frequently the fossa also appears enlarged.

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Inflammatory DisordersRheumatoid Arthritis

• Serological findings
• Presence of rheumatoid factor (RF) in 85 of
  patients.
• RF an IgM-class autoantibody against chemical
  groups on IgG molecules.
• Its significance in RA and other CT diseases is
  unknown, but immune-complex deposition may be the
  mechanism involved.
• Elevated ESR because of hypergammaglobulinemia.

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Osteoarthrosis (Osteoarthritis)

• A degenerative disease which mainly affects
  weight-bearing joints.
• In the TMJ it differs from other joints probably
  because
• It is not a weight-bearing joint.
• The articular surface is covered with fibrous
  tissue rather than hyaline cartilage.
• It is rare in TMJ before 5th decade of life, but
  after that it increases proportionately with age.

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Osteoarthrosis

• Clinical features
• Pain.
• Crepitus.
• Limitation of jaw movement.
• Deviation on opening.
• Many cases are clinically silent.

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Osteoarthrosis

• Clinical features
• Clinical studies suggest a relationship in some
  cases between later development of osteoarthrosis
  and
• untreated myofascial pain-dysfunction syndrome,
• loss of molar support,
• disc displacement.
• Spontaneous resolution is common.

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Osteoarthrosis

• Histological changes
• Early changes consist of uneven distribution of
  cells in articular covering of condyle /- some
  osteoclastic resorption of subarticular bone.
• Vertical splits (fibrillation) develop in
  articular layer.
• Followed by fragmentation and loss of articular
  surface with eventual denudation of underlying
  bone.

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Osteoarthrosis

• Histological changes
• Reactive changes in exposed bone lead to
  thickening of trabeculae and formation of a dense
  surface layer-eburnation.
• Osteophytic lipping on anterior surface may
  occur.
• There may be eventual perforation of the
  articular disc.

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Osteoarthrosis

• Note how broad and flat the top of the condyle
  appears. The disc is destroyed and only a remnant
  remains in front of the condyle.

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Osteoarthrosis

• Radiographic changes
• Variable and not pathognomonic.
• Focal or diffuse areas of bone loss on articular
  surface of condyle.
• Flattening and reduction in total bony size of
  condyle.
• Reduction in joint space. Osteophytes may be seen
  at anterior edge of condyle.
• If large, they may fracture off and present on
  radiographs as loose bodies.

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Osteoarthrosis

• MRI of osteoarthritis the condyle (red arrow)
  takes on a classic "Bird beak" appearance.
• In this more severe case of degenerative
  arthritis, the top of the condyle has been
  completely destroyed (red arrow). The disc (green
  arrow) has been displaced anteriorly.

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Osteoarthrosis
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Osteoarthrosis
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Functional DisordersMyofascial Pain Dysfunction
Syndrome

• Commonest cause of complaint involving TMJ.
• 3 cardinal symptoms
• Pain associated with TMJ or its musculature.
• Clicking of the joint.
• Limitation of joint movement.

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Functional DisordersMyofascial Pain Dysfunction
Syndrome

• More frequent in women with a mean age at
  presentation of 30 years.

• Symptoms vary in intensity during the day.
• Most common in the morning.
• Tenderness to palpation of origins and insertions
  of masticatory muscles is usual.

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Functional DisordersMyofascial Pain Dysfunction
Syndrome
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Functional DisordersMyofascial Pain Dysfunction
Syndrome

• Strong clinical impression of relationship with
  various types of emotional stress.
• Occlusal disharmony common, but no consistent
  relationship.
• Bruxism and tooth clenching common in patients.

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Functional DisordersMyofascial Pain Dysfunction
Syndrome

• Many patients respond to reassurance and training
  in relaxed jaw movement.
• Others may need bite plates (night guard or
  occlusal splint), and medications.
• The principal factor thought to be responsible
  for the symptoms is masticatory muscle spasm
  which may be due to muscular overextension,
  contraction, or fatigue.
• Thought to be self-limiting since it is uncommon
  in old age.

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Functional DisordersDisc Displacement

• Abnormal positional relationship between the
  articular disc, the head of the condyle, and the
  articular fossa of the temporal bone.
• It has been reported in 25-65 of elderly
  patients.

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Functional DisordersDisc Displacement

• It is also prevalent in patients with myofascial
  pain-dysfunction syndrome and/or osteoarthritic
  changes in the joint.
• Whether the displacement precedes or follows such
  changes in unclear.
• Not all patients with displacements have or
  develop signs or symptoms.

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Disc Displacement

• Displacement may be initially an adaptive change
  reflecting remodeling of the disc to prevent
  tissue injury.
• Remodeling is associated with changes in shape
  and proportions of the disc and its posterior
  attachment, and with reactive changes in the
  tissues such as fibrosis and hyalinization in
  retrodiscal tissues.

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Disc Displacement
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Loose Bodies

• Radiopaque bodies apparently lying free within
  the joint space are common in major joints but
  rare in TMJ.
• They may cause discomfort, crepitus, and
  limitation of movement.
• The main causes in TMJ are
• Intracapsular fractures.
• Fractured osteophytes in osteoarthrosis.
• Synovial chondromatosis.

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Loose Bodies

• Synovial Chondromatosis
• disease of unknown etiology characterized by
  formation of multiple nodules of cartilage which
  may calcify and ossify, scattered throughout the
  synovium.
• They may be released in the joint space and
  appear as loose bodies.

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Neoplsams

• Primary neoplasms of the TMJ are rare.
• Benign tumors such as chondromas and osteomas are
  more frequent than sarcomas arising from bone or
  synovial tissues.

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Age Changes in the Jaws TMJ

• Atrophy of alveolar bone is mainly related to
  tooth loss.
• Its extent increases with age, and is probably
  accelerated by osteoporosis.
• It results in loss of facial height, upwards and
  forwards posturing of the mandible, especially in
  the absence of dentures.

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Age Changes in the Jaws TMJ

• In the TMJs, it is difficult to distinguish
  changes due to ageing from those related to
  osteoarthrosis.
• The main changes are related to remodeling of the
  articular surfaces and disc in response to
  functional changes following tooth loss.
• Remodeling may result in anterior displacement of
  the disc.
• There may be perforation of the disc,
  particularly of its posterior attachment with
  progressive joint damage and osteoarthrosis.

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Trismus and Dislocation

• Trismus limitation of movement.
• In the TMJ, temporary trismus is more common than
  permanent trismus.
• Trismus may be caused by intra-articular or
  extra-articular factors.

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Causes of Trismus

• Intra-articular
• Traumatic arthritis
• Infective arthritis
• Rheumatid arthritis
• Dislocation
• Intracapsular fracture
• Fibrous or bony ankylosis following trauma or
  infection

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Causes of Trismus

• Extra-articular
• Adjacent infection, inflammation, and abscesses
  (e.g. mumps, pericoronitis, submasseteric
  abscess)
• Extracapsular fractures (mandible, zygoma, middle
  3rd)
• Overgrowth (neoplasia) of the coronoid process
• Fibrosis from burns or irradiation
• Hematoma/ fibrosis of medial pterygoid (e.g.
  following inferior dental block)
• Myofascial pain-dysfunction syndrome
• Drug-associated dyskinesia psychotic
  disturbances
• Tetanus
• Tetany

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Dislocation

• Dislocation of the TMJ is uncommon.
• Displacement of the condyle out of the glenoid
  fossa beyond the articular eminence.
• Causes of unstable joint
• Abnormal neuromuscular activity.
• Weakness of capsule and lateral ligament.
• Anatomical factors related to contour of glenoid
  fossa or disc.
• Rarely, in some patients, dislocation may be
  recurrent or habitual.