Temporomandibular Disorders (TMDs) or TMJ Dysfunction

TMDs have previously been referred to as TMJ disorders or TMJ dysfunction. The current term of TMDs is more clinically accurate as it encompasses disorders of associated structures as well as the TMJ itself.

Pain-related TMDs may be subdivided into different categories:

• Myalgia/myofascial pain — masticatory muscle disorders.
• Intra-articular disorders — such as disc displacement and/or arthralgia.
• Headache — typically confined to the temporal region.

TMDs may be also classified according to the duration of symptoms:

• Acute TMD pain is often of short duration, self-limiting, and may be related to prolonged jaw opening (such as following dental treatment or trauma).
• Chronic TMD pain is defined as lasting for more than 3 months.

The exact prevalence of temporomandibular disorders is difficult to establish, as the majority of people do not seek help from a healthcare professional. Temporomandibular disorder is the second most common musculoskeletal pain condition after chronic low back pain. It affects more than 35 million people in the US. A US review article suggests that only 5% of adults seek treatment for their symptoms. Females may be affected up to twice as much as males in the general population.

The causes of temporomandibular disorders (TMDs) are not fully understood. They are likely to be complex and multifactorial involving the interaction of anatomical, physiological, and psychosocial risk factors.

• Anatomical factors include internal derangement of the temporomandibular joint (TMJ), such as disc displacement.
• Trauma such as following a dental procedure or a fall onto the chin and parafunctional habits such as bruxism (grinding or clenching of the teeth) may overload the TMJ leading to cartilage breakdown and alterations in the synovial fluid
• Psychosocial factors such as stress, anxiety, and depression are significant predictors for the development of TMDs, and these may predispose to parafunctional habits in some people
• TMD is commonly associated with other chronic pain conditions, such as chronic fatigue syndrome, fibromyalgia, migraine, irritable bowel syndrome, and widespread chronic pain. People with these conditions may have increased generalized pain sensitivity (so-called ‘central sensitization’)

Pain in and around the temporomandibular joint (TMJ) and/or muscles of mastication, which may radiate to other structures.

• Pain typically affects the pre-auricular region and may radiate around the ear, to the temple, teeth, cheek, or angle of the jaw.
• Pain may be provoked by palpation of the masseter and/or temporalis muscles, or the TMJ, and may be provoked or modified by jaw movement or function (such as opening or closing the mouth, or chewing) or parafunction.

Reproducible joint noise of the TMJ (clicking, popping, or crepitus) on any jaw movements, with or without restricted movement or locking of the TMJ.

• Painless clicking may indicate disc displacement with reduction. An inability to open the mouth wide may indicate disc displacement with reduction with intermittent limited opening.
• Persistent closed lock may indicate disc displacement without reduction with limited opening.
• There may be repeated dislocation of the TMJ.
• Note: joint noises may be sporadic, and may occur in up to 50% of asymptomatic people who do not have a TMD.

Headache limited to the temporal region.

Otalgia and/or tinnitus in the absence of ear disease.

MASTICATORY MUSCLE DISORDERS

• Myalgia/myofascial pain
  • Pain is provoked on palpation of the masseter or temporalis masticatory muscles; pain within the body of the muscle or radiating beyond this.
  • Pain with maximum unassisted or assisted mouth opening.
  • Pain in the jaw, temples, pre-auricular area, or inside the ear. Pain is modified with jaw movements, function, or parafunction.
  • The pain is usually (but not always) unilateral, may be intermittent, and is frequently worse in the morning.
  • Myofascial pain with referral may have active muscle trigger points generating pain.

TEMPOROMANDIBULAR JOINT (TMJ) DISORDERS

• Disc displacement with reduction
  • Reproducible joint noise (clicking, popping, or snapping) occurs during mouth opening and closing (usually without significant restriction in jaw movement).
  • Pain, when present, is precipitated by TMJ movement, but it may be asymptomatic.
  • There may be deviation of the mandible during mouth opening that coincides with a click.
  • In a minority of people, it may progress to a ‘closed lock’ state.

• Disc displacement without reduction (‘closed lock’) with or without limited opening
  • There is persistent, markedly limited mouth opening and lateral jaw movement with a history of sudden onset (‘locking’).
  • Deviation of the mandible towards the affected side during mouth opening often occurs.
  • Typically, pain is precipitated if forced mouth opening is attempted, and there is often tenderness of the TMJ.
  • The onset of locking may be preceded by a period of clicking.

• Degenerative joint disease
  • Crepitus (related to articular surface disruption) with any jaw movement, often not associated with pain.
  • Pain from the TMJ occurs on jaw movement and there is point tenderness of the TMJ.
  • There may be restricted jaw movement; deviation of the mandible towards the affected side; and crepitus or grating noises.

• Subluxation
  • History of locking open and need for self-manipulation to achieve closure.
  • Often present in people with hypermobility, associated with deviation of the mandible on mouth opening.

• Arthralgia (may overlap with degenerative joint disease)
  • Pain in the TMJ region produced by palpation or assisted/unassisted jaw movements.
  • Maybe due to factors other than arthritis, for example, overstretching of the TMJ.

• Headache in the temporalis area which is modified with jaw movement, function, or parafunction.
• Headache is reproduced with palpation of the temporalis muscle or with jaw movements.

Specialist investigations may be considered for people with significant functional impairment of the temporomandibular joint (TMJ), and/or an intra-articular disorder such as anterior disc displacement or degenerative joint disease.

• Plain or panoramic X-rays to identify dental pathology, fractures, dislocations, or severe degenerative joint disease.
• CT to assess for degenerative joint disease or subluxation of the TMJ.
• MRI to assess for TMJ disc displacement, subluxation, arthrosis, or synovial proliferation.

Arrange referral to oral medicine or oral and maxillofacial surgery for specialist investigations and management, depending on clinical judgement, if a person has:

• A history of trauma or fracture of the temporomandibular joint (TMJ) complex.
• Markedly limited mouth opening (closed lock) suggesting disc displacement without reduction.

For all other people with a suspected TMD, encourage early self-management to help control symptoms and limit functional impairment:

• Reassure that the condition is usually non-progressive and that the symptoms may fluctuate, but should improve.
• Eat a soft diet and rest the jaw if there is acute pain.
• Try to avoid parafunctional activities that may exacerbate symptoms, such as wide yawning, teeth grinding or jaw clenching, chewing gum or pencils, and nail-biting.
• Consider simple analgesia for short-term use, such as paracetamol or a nonsteroidal anti-inflammatory drug (NSAID).
• Consider local measures for pain relief, such as applying covered ice or a warm flannel or heat pad, or massaging affected muscles.
• Try to identify sources of stress, and give advice on relaxation techniques, setting realistic targets, pacing activities, and getting social support where available. Manage any co-morbid depression.

Consider whether additional drug treatment may be helpful for adults:

• If symptoms are acute and severe, consider prescribing a short course of a low-dose benzodiazepine such as diazepam 2 mg up to three times daily, for a maximum of 2 weeks.
• If there is chronic pain, consider prescribing a neuropathic analgesic such as amitriptyline (off-label) or gabapentin (off-label).

Consider referral to additional specialists if appropriate, such as to:

• A dentist, if there is poor dental health, suspected malocclusion or dental pathology, or for consideration of an occlusal splint (usually worn at night; particularly useful for people who grind or clench their teeth). Note: referral to the local dental hospital or oral and maxillofacial surgery department may be appropriate depending on the person’s ability to pay for dental treatment.
• Psychology services for cognitive behavioural therapy (CBT), if there is marked psychological distress associated with symptoms, or to help with pain-related anxiety.
• Physiotherapy for advice on passive jaw stretching exercises, posture training, and massage or acupuncture to help relax muscle spasm, if available.

INTRAARTICULAR STEROID INJECTION

This should be considered in patients with degenerative disorder of the TMJ. A steroid injection can help reduce pain and swelling in a joint or the surrounding soft tissue. Most people report feeling less pain within the first 24 hours to one week.

BOTULINUM TOXIN INJECTION

The most commonly affected muscles are the temporalis muscle, masseter muscle and lateral pterigoid muscles. The temporalis muscle and masseter muscle are almost always involved and usually manifest as direct muscle pain. Lateral pterygoids involvement usually manifests as buccal pain, lateral jaw deviation or bruxism. We typically use a concentration of 2.5–5.0 units per 0.1 mL of Botox with a starting dose of 10–25 units for each temporalis muscle, 25–50 units to the masseter muscles and 7.5–10 units to the lateral pterygoids. Subsequent doses are individualized and are based on the patients’ response.

Approximately 3-4 weeks after the initial injection, patients are reevaluated for any adverse effects and/or suboptimal responses. Some patients may require a booster injection at that time. Additional BoNT injections are directed by the patients’ history and clinical examination, and pain diaries are a useful guide to help in patient directed therapy. It may take several weeks before patients experience the maximum pain relief from BoNT. Although the typical duration of efficacy is 12 weeks, we have noted tremendous variability among patients with respect to optimal dosing frequency. Some patients experience relief well beyond the predicted pharmacokinetic duration of the drug supporting the possibility that BoNT does not strictly act at the periphery and may be involved in neuromodulation at the level of the central nervous system. It is important to note that an individual patient’s response to toxin may change over time, which further supports the importance of patient-directed dosing.