Temporomandibular Joint Dysfunction (TMD)

Temporomandibular joint dysfunction (TMD) encompasses pain and dysfunction of the jaw muscles and temporomandibular joints (TMJ). It can significantly impact quality of life due to chronic and difficult-to-manage symptoms such as pain, restricted jaw movement, and joint noises.

Classification

TMD is categorised into muscular and arthrogenic types. Muscular causes include hyperactivity, spasm, inflammation, trauma, myofascial pain, and fibromyalgia. Arthrogenic causes encompass disc displacement, dislocation, arthritis, infections, metabolic diseases, capsulitis, ankylosis, fractures, and neoplasia.

Definitions and Terminology

TMD is a cluster of related disorders rather than a single syndrome. Terminology varies geographically; in the UK, "pain dysfunction syndrome" is common, while in the US, "temporomandibular disorder" is preferred. Definitions also differ, with some describing TMD as musculoskeletal disorders affecting the TMJs and associated musculature.

Signs and Symptoms

TMD symptoms typically involve pain and tenderness in the jaw muscles or TMJ, limited jaw movement, and joint noises such as clicking or crepitus. Pain is usually dull, intermittent, and localised in front of the ear. Additional symptoms may include headaches, neck pain, hearing loss, tinnitus, dizziness, and a sensation of malocclusion.

Causes

TMD's aetiology is multifactorial and poorly understood, often involving genetic, hormonal, anatomical, and psychosocial factors. Commonly proposed causes include:

• Disc Displacement: Tear in the joint capsule leading to anterior disc displacement.
• Degenerative Joint Disease: Osteoarthritis or rheumatoid arthritis affecting the TMJs.
• Psychosocial Factors: Stress, anxiety, and depression increasing muscle activity and pain.
• Bruxism: Excessive clenching and grinding of teeth, particularly during sleep.
• Trauma: Both microtrauma and macrotrauma, including prolonged mouth opening and whiplash injuries.
• Occlusal Factors: Although controversial, occlusal abnormalities were historically considered a cause.

Diagnosis

Diagnosis involves clinical examination and may include auscultation for joint noises, palpation for tenderness, and assessment of jaw movement. The Research Diagnostic Criteria (RDC/TMD) is often used, involving physical (axis I) and psychological (axis II) diagnoses.

Medical Imaging

Imaging techniques are useful for diagnosing TMD of articular origin:

• Plain Radiography and Panoramic Tomography: Limited to extensive lesions due to superimposition issues.
• Computed Tomography (CT) and Cone Beam CT (CBCT): Provide detailed views of bony components.
• Magnetic Resonance Imaging (MRI): Gold standard for soft tissue evaluation, particularly for disc position and intra-articular changes.
• Ultrasound: Useful for initial assessment, especially in MRI contraindicated individuals.

Management

Management of TMD is multidisciplinary, often involving reversible, non-invasive treatments.

Psychosocial and Behavioural Interventions

Psychosocial factors play a significant role in TMD. Cognitive Behavioural Therapy (CBT) and relaxation techniques like yoga and meditation are beneficial.

Devices

Occlusal splints, made of acrylic, are commonly used. They can be full or partial coverage, designed for upper or lower teeth. Stabilisation splints are more complex but may reduce pain severity.

Medication

Pain management includes analgesics, benzodiazepines, anticonvulsants, muscle relaxants, and topical treatments. Injections of local anaesthetics, steroids, and botulinum toxin are also used.

Physiotherapy

Physiotherapy focuses on increasing jaw movement range and reducing pain through stretching exercises, massage, and possibly TENS or ultrasound.

Surgery

Surgical interventions like arthrocentesis, arthroscopy, and joint replacement are reserved for severe cases. Surgical outcomes can be variable, with potential for worsening symptoms.

Alternative Medicine

Acupuncture and chiropractic adjustments are sometimes used, though evidence of efficacy is limited. Acupuncture may provide short-term pain relief, while chiropractic care for TMD lacks strong evidence.

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Self-assessment MCQs (single best answer)

Which classification of TMD includes conditions like myofascial pain and fibromyalgia?

In the UK, what term is commonly used to refer to TMD?

Which imaging technique is considered the gold standard for evaluating soft tissues in TMD?

Which of the following is NOT a common symptom of TMD?

What is the primary goal of using occlusal splints in TMD management?

Which of the following is a reversible and non-invasive treatment for TMD?

What condition involves the excessive clenching and grinding of teeth, often during sleep, and is associated with TMD?

Which factor is NOT commonly proposed as a cause of TMD?

Which medical imaging technique provides detailed views specifically of the bony components of the TMJ?

Which intervention is typically reserved for severe cases of TMD due to the potential for variable outcomes and worsening symptoms?