Temporomandibular Joint Disorder (TMD)

BASICS

DESCRIPTION

  • Syndrome characterized by
    • Pain and tenderness involving the muscles of mastication and surrounding tissues
    • Sound, pain, stiffness, or grating in the temporomandibular joint (TMJ) with movement
    • Limitation of mandibular movement with possible locking or dislocation
    • Recent research suggests that TMD is a complex disorder with multiple causes consistent with a biopsychosocial model of illness.
  • System(s) affected: musculoskeletal
  • Synonym(s): TMJ syndrome; TMJ dysfunction; myofascial pain–dysfunction syndrome; bruxism; orofacial pain

EPIDEMIOLOGY

Incidence

  • Annual first-onset incidence is 3.9%.
  • Greatest risk of onset is between 18 and 44 years

Prevalence

  • May be as high as 31% in adults and 11% in children
  • 1.5 times higher in females than males
  • Up to 50% of people may have at least one symptom of TMD, but most are not limited by symptoms.
  • <1:4 seek treatment.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Pathophysiology is multifactorial and includes anatomic, behavioral, emotional, and cognitive origins, akin to other chronic pain disorders that reflect CNS sensitization.
  • The American Academy of Orofacial Pain categorizes TMD according to three anatomic origins of pain, including the following:
    • Muscle disorders involving the muscles of mastication
      • Bruxism
      • Masticatory muscle spasm
      • Myositis
      • Myofibrosis
      • Poorly fitting oral devices (dentures, splints)
      • Contracture
      • Neoplasia
    • Articular disorders of the joint
      • Congenital disorders
      • Inflammatory disorders (synovitis, arthritides, capsulitis, ankyloses)
      • Avascular necrosis
      • TMJ disk derangement, osteoarthritis
      • Hyper- or hypomobile TMJ
      • TMJ trauma (condylar fractures, dislocation)
    • Cranial bone disorders including the mandible
      • Congenital and developmental disorders
      • Acquired disorders (fracture, neoplasm)

Genetics

Gene polymorphisms, such as catechol O-methyltransferase (COMT), is thought to be associated with changes in pain responsiveness in TMD

RISK FACTORS

  • Trauma to the face, jaw, and neck
  • Rheumatologic and degenerative conditions involving the TMJ
  • Psychosocial stress and poor adaptive capabilities
  • Repetitive microtrauma from dental malocclusion, including inappropriate dental treatment
  • Inconsistent association with bruxism and jaw/teeth clenching
  • Hormonal contraceptive use
  • Repetitive jaw motions and positions may be associated

GENERAL PREVENTION

  • Elimination of tension-causing oral habits
  • Stress reduction
  • Reduction in overall muscle tension

COMMONLY ASSOCIATED CONDITIONS

Craniomandibular disorders, somatization disorder, somatoform pain disorder, other chronic pain syndromes, fibromyalgia, juvenile idiopathic arthritis, tension headache, irritable bowel syndrome, sleep disturbance, tobacco use

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