Temporomandibular Joint Dysfunction

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Temporomandibular Joint Dysfunction

Temporomandibular Joint Disorders

Temporomandibular joint disorders are commonly seen in clinical practice. They are reported to be more common in women and have a peak age incidence of 20–40 years. Clinical presentations of temporomandibular joint disorders are characterised by acute or chronic pain and may include the following:

• Temporomandibular joint dysfunction
• Facial pain
• Ear pain, a feeling of ear fullness, and tinnitus
• Neck pain
• Orbital pain
• Dizziness

Temporomandibular Joint Dysfunction

Temporomandibular joint dysfunction is characterized by pain arising from an abnormal relationship between the temporomandibular joint (TMJ) articular disc and the adjacent articular surfaces, as well as the surrounding myofascial structures.

The TMJ is an extremely important articulation necessary for mastication, swallowing, facial expression, and communication. This joint is classified as a ginglymoarthrodial joint allowing essentially a hinge-like movement (rotation) combined with a gliding motion (translation). On opening the mouth, the movement begins with rotation of the mandibular condyle in the glenoid fossa, followed by a forward translation of the condyles.

The TMJ involves articulation between the mandibular condyle and the glenoid fossa of the temporal bone. These two osseous structures are separated by a fibrocartilagenous disc. The TMJ is strengthened by its joint capsule and several ligaments (the sphenomandibular, stylomandibular, pterygomandibular, malleolomandibular and collateral ligaments).

The muscles involved in the opening and closing of the mouth are the primary muscles of mastication, including the masseter, temporalis, and medial pterygoid muscles which elevate the mandible to close the mouth, and the lateral pterygoid muscle which assists in opening the mouth by guiding forward movement of the jaw. Innervation of the TMJ and its associated muscles involves branches of the third division of the trigeminal nerve.

The etiology of TMJ dysfunction is thought to be multifactorial, including anatomical, pathophysiological, and psychosocial factors. Musculoskeletal dysfunction is the most common contributing factor to TMJ dysfunction. This could be due to the following:

• Joint trauma
• Muscle imbalance
• Poor head and neck posture
• Myofascial pain syndromes
• Internal joint derangement
• Degenerative joint disease
• Chronic bruxism (clenching or grinding the teeth)
• Dental malocclusion
• A physical manifestation of a psychological disorder (e.g., depression, anxiety, or post-traumatic stress disorder)

Differential Diagnosis of Orofacial Pain

Patients presenting with orofacial pain may be suffering from several conditions. The differential diagnosis includes the following:

• TMJ dysfunction
• Dental caries, abscess, or malocclusion
• Otitis media and otitis externa
• Upper cervical facet joint dysfunction
• Mastoiditis
• Migraine headache
• Cluster headache
• Tension-type headache
• Trigeminal neuralagia
• Post-herpetic neuralgia
• Giant cell arteritis (Temporal arteritis)
• Parotitis
• Mandibular fracture or dislocation
• Sinusitis
• Cancer of the jaw, head, or neck

• Preauricular pain that is usually described as deep and aching with sharp exacerbations on jaw movement
• Pain that may refer to the head and neck
• Pain that is aggravated by chewing, yawning, or talking for extended periods
• Joint clicking, popping, or snapping on jaw movement
• Limited jaw opening
• May have jaw-locking
• Headache
• May have associated otological symptoms (e.g., tinnitus, vertigo, earache, or hearing loss)

• Abnormal mandibular movement
• Decreased TMJ range of motion (inability to fully open the mouth, typically 25 mm or less)
• Local tenderness over the joint and/or in the muscles of mastication
• Palpation may reveal a clicking or popping sensation with jaw movement
• Palpation may reveal grinding or crepitus with jaw movement
• Muscle tension or spasm
• Pain on jaw clenching due to dynamic loading
• May have evidence of tooth wear or malocclusion
• May have abnormal cervical posture

The diagnosis of TMJ dysfunction is usually clinical. Plain radiography can help to rule out degenerative joint disease, fractures, dislocations, and bone pathology. Magnetic resonance imaging (MRI) is considered the gold standard for the investigation of TMJ disorders as it is able to assess soft tissue structures, articular disc displacement, and the presence of joint effusion.

The following are examples of red flags for patients presenting with orofacial pain:

• A history of significant injury
• Severe pain
• Unrelenting pain
• Nocturnal pain
• Unexplained weight loss
• Fever
• Deformity
• Trismus
• Significant swelling
• Unilateral hearing loss or a new onset of tinnitus
• Vestibular dysfunction
• Significant loss of range of motion
• Severe tenderness on palpation or severe pain with any examination procedure

If any red flags are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.

TMJ Palpation

When palpating the TMJ (e.g., by placing fingers in the patient’s ears while they open and close their mouth), if a crackling or grating sound or sensation is present, this suggests osteoarthritis. If a clicking sensation is present, this could indicate displacement of the intra-articular disc.

Innervation of the TMJ and Associated Muscles 

Since innervation of the TMJ and its associated muscles involves branches of the third division of the trigeminal nerve, pain from mandibular pathology or the mandibular teeth can be referred to the preauricular area and misinterpreted as arising from TMJ dysfunction. On the other hand, pain arising from the TMJ may be perceived by the patient as an earache.

Myofascial Pain Syndrome Presenting as TMJ Pain

In patients presenting with TMJ pain, a complete clinical examination should include an evaluation for the presence of myofascial trigger points as either the primary cause of the pain or as a concomitant condition. The primary muscles to evaluate include the following:

• Medial Pterygoid: Pain primarily in the region of TMJ
• Lateral Pterygoid: Pain primarily in the region of TMJ and maxillary area sometimes resembling as “sinus pain”
• Masseter – Superficial Layer: Pain primarily in the lowewr jaw and zygomatic arch
• Masseter – Deep Layer: Pain primarily in the TMJ (trigger point palpated intraorally)
• Sternocleidomastoid – Clavicular Division: Pain primarily in the forehead (may refer to both sides), pain deep in the “ear” with/without feeling of lightheadedness and imbalance
• Sternocleidomastoid – Sternal Division: Pain primarily in the temporal region and deep behind the eye