Lower Jaw Dislocation: Causes, Symptoms, Treatment, and Prevention

What is dislocation of lower jaw?

A dislocation of the lower jaw, medically known as a temporomandibular joint (TMJ) dislocation or mandibular dislocation, occurs when the condyle (the rounded end) of the mandible (lower jawbone) moves out of its normal position within the glenoid fossa (a socket in the temporal bone of the skull), preventing the jaw from closing properly.

Understanding the Temporomandibular Joint (TMJ)

The temporomandibular joint (TMJ) is a complex, bilateral synovial joint that connects the mandible to the temporal bone of the skull. It is one of the most frequently used joints in the human body, facilitating essential functions such as chewing, speaking, and swallowing.

• Anatomy: The TMJ comprises several key components:

  • Mandibular Condyle: The rounded upper end of the lower jawbone.
  • Glenoid Fossa: A depression in the temporal bone of the skull where the condyle rests.
  • Articular Disc: A small, oval-shaped piece of cartilage (fibrocartilage) located between the condyle and the fossa. This disc acts as a shock absorber, facilitates smooth movement, and divides the joint into two compartments.
  • Joint Capsule: A fibrous tissue sac that encloses the joint, providing stability.
  • Ligaments: Strong bands of connective tissue (e.g., lateral ligament, sphenomandibular ligament, stylomandibular ligament) that reinforce the joint capsule and limit excessive movement.
  • Muscles of Mastication: Muscles like the masseter, temporalis, medial pterygoid, and lateral pterygoid are responsible for jaw movement. The lateral pterygoid muscle, in particular, plays a crucial role in pulling the condyle forward during mouth opening.

• Function: The TMJ allows for a combination of hinge-like (rotational) and gliding (translational) movements. When the mouth opens, the mandibular condyle first rotates within the glenoid fossa, then translates (slides) forward and downward along the articular eminence (a bony prominence anterior to the fossa). This complex motion is essential for wide opening.

What is a Dislocation?

A lower jaw dislocation occurs when the mandibular condyle translates too far forward, moving beyond the articular eminence and getting "stuck" in front of it. This prevents the jaw from returning to its closed position. It can affect one side (unilateral) or both sides (bilateral) of the jaw.

• Mechanism: Typically, a dislocation happens when the jaw opens excessively wide, causing the condyle to slide beyond its normal physiological limits. The muscles of mastication, particularly the lateral pterygoid, can then go into spasm, locking the condyle in its dislocated position.

Causes of Lower Jaw Dislocation

Dislocations of the lower jaw can result from various factors, often involving an extreme range of motion or direct trauma.

• Excessive Mouth Opening:
  • Yawning: A very wide yawn is a common cause.
  • Vomiting: Forceful emesis can lead to dislocation.
  • Dental Procedures: Prolonged periods with the mouth held wide open during dental work.
  • Intubation: During medical procedures requiring airway access.
  • Shouting or Laughing: Vigorous vocalization or laughter.
• Trauma:
  • Direct Blows: A punch or fall directly to the chin can force the jaw out of alignment.
  • Motor Vehicle Accidents: Impact can cause jaw displacement.
• Underlying Conditions:
  • Ligamentous Laxity: Individuals with naturally loose ligaments (e.g., Ehlers-Danlos syndrome, generalized joint hypermobility) are more prone to dislocations.
  • Anatomical Abnormalities: A flattened articular eminence or shallow glenoid fossa can predispose individuals to recurrent dislocations.
  • Chronic TMJ Disorders: Pre-existing issues with the TMJ can weaken its stability.
  • Muscle Spasms: Conditions causing severe muscle spasms, such as dystonia or tetanus, can lead to dislocation.

Signs and Symptoms

The signs and symptoms of a dislocated lower jaw are usually immediate and quite distinct.

• Inability to Close the Mouth: This is the most prominent symptom. The jaw remains wide open, often with the chin pointing to one side if the dislocation is unilateral.
• Severe Pain: Intense pain in the jaw joint, ear, and surrounding facial muscles.
• Visible Deformity: The jaw may appear visibly out of alignment, shifted to one side, or protruded forward.
• Difficulty Speaking and Swallowing: Articulation becomes challenging, and swallowing is often painful or impossible due to the inability to close the mouth.
• Excessive Salivation: Due to the inability to swallow normally.
• Facial Muscle Spasm: Muscles around the jaw may feel rigid and tender.

Diagnosis

Diagnosis of a lower jaw dislocation is typically straightforward and based on clinical presentation.

• Clinical Examination: A healthcare professional can usually diagnose a dislocated jaw by observing the patient's inability to close their mouth, the characteristic jaw position, and palpating the TMJ area.
• Imaging Studies: While often not strictly necessary for diagnosis, imaging may be used to confirm the dislocation, rule out fractures, or assess for underlying anatomical issues, especially in cases of trauma or recurrent dislocations.
  • X-rays: Provide a basic view of the bones.
  • CT Scans: Offer more detailed cross-sectional images, useful for complex cases or suspected fractures.

Treatment and Management

The primary treatment for an acute lower jaw dislocation is manual reduction.

• Manual Reduction: This procedure involves a healthcare professional (doctor, dentist, or oral surgeon) manually repositioning the jaw back into its socket.
  • The technique typically involves applying downward and backward pressure to the lower molars, guiding the condyle back over the articular eminence and into the glenoid fossa.
  • Sedation or local anesthesia may be used to relax the muscles and minimize pain, especially in cases of severe muscle spasm or patient anxiety.
• Post-Reduction Care:
  • Jaw Immobilization: After reduction, the jaw may be gently bandaged (e.g., a Barton bandage) or a soft cervical collar may be used for a short period (usually 1-3 days) to limit movement and allow the joint capsule and ligaments to heal.
  • Soft Diet: Patients are advised to consume soft foods for several days to weeks to avoid straining the joint.
  • Avoid Wide Opening: It is crucial to avoid excessive yawning, shouting, or chewing hard foods during the recovery period.
  • Pain Management: Over-the-counter pain relievers (NSAIDs) or muscle relaxants may be prescribed.
• Surgical Intervention: Surgery is rarely needed for acute dislocations but may be considered for:
  • Chronic Recurrent Dislocations: Procedures to tighten ligaments, reshape the articular eminence (eminoplasty), or restrict condylar movement may be performed.
  • Associated Fractures: If the dislocation is accompanied by a jaw fracture.

Recovery and Prevention

Recovery after a jaw dislocation involves protecting the joint and gradually restoring normal function. Prevention focuses on avoiding triggers, especially for those prone to recurrence.

• Recovery:
  • Rest: Allow the joint to rest and heal.
  • Gradual Return to Activity: Slowly reintroduce normal jaw movements and diet.
  • Physical Therapy/Rehabilitation: For recurrent dislocations or persistent symptoms, a physical therapist specializing in TMJ disorders can provide exercises to strengthen jaw muscles, improve joint stability, and increase range of motion without overstretching. These might include:
    • Gentle Jaw Opening Exercises: Controlled, limited opening to maintain mobility.
    • Isometric Exercises: Gentle resistance against jaw movement to strengthen muscles.
    • Posture Correction: Addressing head and neck posture that might influence jaw mechanics.
  • Occlusal Splints: Custom-made mouthguards may be recommended to reduce stress on the TMJ, especially during sleep.
• Prevention:
  • Control Yawning: Place a fist under your chin when yawning to prevent excessive opening.
  • Manage Dental Appointments: Inform your dentist if you have a history of jaw dislocations. They can use bite blocks or take breaks during long procedures.
  • Avoid Hard/Chewy Foods: Limit foods that require extensive chewing, especially if prone to dislocation.
  • Address Bruxism/Clenching: If you grind or clench your teeth, address this with a nightguard or stress management techniques.
  • Jaw Awareness: Be mindful of jaw posture, keeping teeth slightly apart and the tongue resting on the roof of the mouth.
  • Treat Underlying Conditions: Manage any conditions that contribute to joint laxity or muscle spasms.

When to Seek Medical Attention

Immediately seek emergency medical attention if you suspect a dislocated lower jaw. Prompt reduction is essential to minimize pain and muscle spasm. If you experience recurrent dislocations or persistent jaw pain and dysfunction after a previous dislocation, consult with an oral and maxillofacial surgeon, an ENT specialist, or a TMJ specialist.