Temporal–mandibular Joint Injury/syndrome

Basics

Description

  • Myofascial pain causing temporomandibular joint (TMJ) dysfunction
  • Prevalence of 40–75% of 1 sign of TMJ disorder
  • Most common in 18–44 yr olds
  • Higher prevalence in women by 1.5×
  • 40% have symptoms that resolve spontaneously
  • TMJ is a synovial joint:
    • Allows for hinge and sliding movements
    • Normal range is 35–55 mm (maxillary to mandible incisors)
  • Articular disorders:
    • Congenital or developmental
    • Degenerative joint disorders:
      • Inflammatory (rheumatoid arthritis)
      • Noninflammatory (osteoarthritis)
    • Trauma
    • TMJ hypermobility:
      • Laxity
      • Dislocation
      • Subluxation
    • TMJ hypomobility:
      • Trismus
      • Fibrosis
    • Infection
    • Neoplasm
  • Masticatory muscle disorders:
    • Local myalgias
    • Myositis
    • Muscle spasm
    • Contracture
    • Myofascial pain disorder
  • TMJ clicking:
    • May be normal finding; present as a transient finding in 40–60% of the population
    • TMJ motion: Limited by adhesions within the joint or disk displacement or trismus from muscle spasm
  • Intra-articular disk disorder:
    • Anterior displacement with reduction:
      • Displacement in closed mouth position
      • Often with a click and variable pain with opening mouth
      • May worsen over time
    • Anterior disk displacement without reduction:
      • Disk is a mechanical obstruction to opening mouth
      • Maximal opening may be limited to 20–25 mm
      • Often difficult to correct

Etiology

TMJ dysfunction is poorly understood:
  • Multifactorial:
    • Bruxism (teeth grinding)
    • Trauma
    • Malocclusion
  • Onset can be related to stress

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