Temporomandibular joint dysfunction


Temporomandibular joint dysfunction is an umbrella term for a spectrum of disorders relating to pain and dysfunction of the muscles of mastication and the temporomandibular joints. The major common presenting symptoms are pain, alterations in the range of mandibular movement, and/or noises from the temporomandibular joints during function. Although TMD is not life-threatening, it can be detrimental to quality of life, especially in the form of chronic pain.
In this article, the term temporomandibular disorder is taken to mean any disorder that affects the temporomandibular joint or masticatory muscles, and temporomandibular joint disorder is taken to mean dysfunction of the temporomandibular joint. However, there is no single, globally accepted term or definition concerning this topic.
TMDs have a range of causes and often co-occur with a number of overlapping medical conditions, including headaches, fibromyalgia, back pain, and irritable bowel. However, these factors are poorly understood, and there is disagreement as to their relative importance. There are many treatments available, although there is a general lack of evidence for any treatment in TMD, and no widely accepted treatment protocol. Common treatments include provision of occlusal splints, psychosocial interventions like cognitive behavioral therapy, physical therapy, and pain medication or others. Most sources agree that no irreversible treatment should be carried out for TMD.
The prevalence of TMD in the global population is 34%. It varies by continent: the highest rate is in South America at 47%, followed by Asia at 33%, Europe at 29%, and North America at 26%. About 20% to 30% of the adult population are affected to some degree. Usually people affected by TMD are between 20 and 40 years of age, and it is more common in females than males. TMD is the second most frequent cause of orofacial pain after dental pain. By 2050, the global prevalence of TMD may approach 44%.

Classification

Temporomandibular Joint Disorders
  1. Joint pain
  2. # Arthralgia
  3. # Arthritis
  4. Joint disorders
  5. # Disc disorders
  6. ## Disc displacement with reduction
  7. ## Disc displacement with reduction with intermittent locking
  8. ## Disc displacement without reduction with limited opening
  9. ## Disc displacement without reduction without limited opening
  10. # Hypomobility disorders other than disc disorders
  11. ## Adhesions/Adherence
  12. ## Ankylosis
  13. ### Fibrous
  14. ### Osseous
  15. # Hypermobility disorders
  16. ## Dislocations
  17. ### Subluxation
  18. ### Luxation
  19. Joint diseases
  20. # Degenerative joint disease
  21. ## Osteoarthrosis
  22. ## Osteoarthritis
  23. # Systemic arthritides
  24. # Condylysis/Idiopathic condylar resorption
  25. # Osteochondritis dissecans
  26. # Osteonecrosis
  27. # Neoplasm
  28. # Synovial Chondromatosis
  29. Fractures
  30. Congenital/developmental disorders
  31. # Aplasia
  32. # Hypoplasia
  33. # Hyperplasia
Masticatory Muscle Disorders
  1. Muscle pain
  2. # Myalgia
  3. ## Local myalgia
  4. ## Myofascial pain
  5. ## Myofascial pain with referral
  6. # Tendonitis
  7. # Myositis
  8. # Spasm
  9. Contracture
  10. Hypertrophy
  11. Neoplasm
  12. Movement Disorders
  13. # Orofacial dyskinesia
  14. # Oromandibular dystonia
  15. Masticatory muscle pain attributed to systemic/central pain disorders
  16. # Fibromyalgia/widespread pain
Headache
  1. Headache attributed to TMD
Associated Structures
  1. Coronoid hyperplasia
TMD is considered by some to be one of the four major symptom complexes in chronic orofacial pain, along with burning mouth syndrome, atypical facial pain and atypical odontalgia. TMD has been considered as a type of musculoskeletal, neuromuscular, or rheumatological disorder. It has also been called a functional pain syndrome, and a psychogenic disorder. It is hypothesized that there is a great deal of similarity between TMD and other pain syndromes like fibromyalgia, irritable bowel syndrome, interstitial cystitis, headache, chronic lower back pain and chronic neck pain.

Definitions and terminology

Frequently, TMD has been treated as a single syndrome, but the prevailing modern view is that TMD is a cluster of related disorders with many common features. Indeed, some have suggested that, in the future, the term 'TMD' may be discarded as the different causes are fully identified and separated into different conditions. Sometimes, "temporomandibular joint dysfunction" is described as the most common form of temporomandibular disorder, whereas many other sources use the term 'temporomandibular disorder' synonymously, or instead of the term 'temporomandibular joint dysfunction'. In turn, the term 'temporomandibular disorder' is defined as "musculoskeletal disorders affecting the temporomandibular joints and their associated musculature. It is a collective term which represents a diverse group of pathologies involving the temporomandibular joint, the muscles of mastication, or both". Another definition of temporomandibular disorders is "a group of conditions with similar signs and symptoms that affect the temporomandibular joints, the muscles of mastication, or both." 'Temporomandibular disorder' is a term that creates confusion since it refers to a group of similarly symptomatic conditions, whilst many sources use the term temporomandibular disorders as a vague description, rather than a specific syndrome, and refer to any condition which may affect the temporomandibular joints. The temporomandibular joint is susceptible to a huge range of diseases, some rarer than others, and there is no implication that all of these will cause any symptoms or limitation in function at all. Only 33% of those with signs of TMD will have symptoms.
The preferred terms in medical publications is to an extent influenced by geographic location. For example, in the United Kingdom, the term 'pain dysfunction syndrome' is in common use. In the United States, the term 'temporomandibular disorder' is generally favored. The American Academy of Orofacial Pain uses 'temporomandibular disorder', whilst the National Institute of Dental and Craniofacial Research uses 'temporomandibular joint disorder'. A more complete list of synonyms for this topic is extensive, with some being more commonly used than others. In addition to those already mentioned, examples include 'temporomandibular joint pain dysfunction syndrome', 'temporomandibular pain dysfunction syndrome', 'temporomandibular joint syndrome', 'temporomandibular dysfunction syndrome', 'temporomandibular dysfunction', 'temporomandibular disorder', 'temporomandibular syndrome', 'facial arthromyalgia', 'myofacial pain dysfunction syndrome', 'craniomandibular dysfunction', 'myofacial pain dysfunction', 'masticatory myalgia', 'mandibular dysfunction', and 'Costen's syndrome'.
The lack of standardization in terms is not restricted to medical papers. Notable internationally recognized sources vary in both their preferred term, and their offered definition. For example:

By cause and symptoms

Some classification systems distinguish muscle-related TMD from joint-related TMD, based upon whether the muscles of mastication or the TMJs themselves are predominantly involved. This classification, which effectively divides TMD into 2 syndromes, is followed by the American Academy of Orofacial Pain. However, since most people with TMD could be placed into both of these groups, it makes a single diagnosis difficult when this classification is used. The Diagnostic Criteria allows for multiple diagnoses in an attempt to overcome the problems with other classifications. DC/TMD considers temporomandibular disorders in 2 axes; axis I is the physical aspects, and axis II involves assessment of psychological status, mandibular function and TMD-related psychosocial disability. Axis I is divided into 5 general groups of disorders and allows for diagnoses from each group for each joint. These include the muscle pain, joint pain, disc displacement, degenerative joint disorder, and subluxation disorder diagnoses. Axis II assessments allows clinicians to evaluate the impact of TMD on quality of life in the process of diagnosis, and treatment planning.
It has been suggested that TMD may develop following physical trauma, particularly whiplash injury, although the evidence for this is not conclusive. This type of TMD is sometimes termed "posttraumatic TMD" to distinguish it from TMD of unknown cause, sometimes termed "idiopathic TMD".

By duration

Sometimes distinction is made between acute TMD, where symptoms last for less than three months, and chronic TMD, where symptoms last for more than three months. Not much is known about acute TMD since these individuals do not typically attend in secondary care.

Signs and symptoms

Signs and symptoms of temporomandibular joint disorder vary in their presentation. The symptoms will usually involve more than one of the various components of the masticatory system, muscles, nerves, tendons, ligaments, bones, connective tissue, or the teeth.
The three classically described, cardinal signs and symptoms of TMD are:
  1. Pain and tenderness on palpation in the muscles of mastication, or of the joint itself. Pain is the defining feature of TMD and is usually aggravated by manipulation or function, such as when chewing, clenching, or yawning, and is often worse upon waking. The character of the pain is usually dull or aching, poorly localized, and intermittent, although it can sometimes be constant. The pain is more usually unilateral rather than bilateral. It is rarely severe.
  2. Limited range of mandibular movement, which may cause difficulty eating or even talking. There may be locking of the jaw, or stiffness in the jaw muscles and the joints, especially present upon waking. There may also be incoordination, asymmetry or deviation of mandibular movement.
  3. Noises from the joint during mandibular movement, which may be intermittent. Joint noises may be described as clicking, popping, or crepitus.
TMJ dysfunction is commonly associated with symptoms affecting cervical spine dysfunction and altered head and cervical spine posture.
Other signs and symptoms have also been described, although these are less common and less significant than the cardinal signs and symptoms listed above. Examples include: