Jaw Dislocation: Understanding Causes, Symptoms, and Treatment

How did my jaw get dislocated?

A jaw dislocation occurs when the temporomandibular joint (TMJ) components, specifically the mandibular condyle, move out of their normal alignment with the temporal bone, often becoming locked in an open position due to excessive movement or trauma.

Understanding Your Jaw Anatomy: The Temporomandibular Joint (TMJ)

To comprehend how a jaw can dislocate, it's crucial to first understand the anatomy of the temporomandibular joint (TMJ). The TMJ is one of the most complex joints in the human body, facilitating the diverse movements required for chewing, speaking, and yawning.

• Components: The TMJ is formed by the mandibular condyle (the rounded end of the lower jawbone) fitting into the glenoid fossa (a depression in the temporal bone of the skull). Between these two bones lies a small, oval-shaped piece of cartilage known as the articular disc. This disc acts as a shock absorber and allows for smooth movement.
• Ligaments and Muscles: The joint is stabilized by several strong ligaments, including the temporomandibular ligament, and is surrounded by a joint capsule. A complex network of muscles, such as the masseter, temporalis, medial pterygoid, and lateral pterygoid, control the jaw's movement.
• Unique Movement: Unlike a simple hinge joint, the TMJ allows for both a hinging motion (opening and closing) and a gliding or sliding motion (forward, backward, and side-to-side). This gliding action, where the condyle moves anteriorly and inferiorly down the articular eminence during wide opening, is particularly relevant to dislocations.

What is a Jaw Dislocation?

A jaw dislocation, medically known as mandibular luxation, occurs when the mandibular condyle separates from the glenoid fossa and becomes locked outside its normal anatomical position. This usually happens when the condyle moves too far forward (anteriorly) and gets stuck beyond the articular eminence, a bony prominence just in front of the glenoid fossa.

• Anterior Dislocation: This is by far the most common type. The jaw becomes locked in an open position, unable to close.
• Posterior or Lateral Dislocation: These are extremely rare and typically result from severe direct trauma.

Common Mechanisms and Causes of Jaw Dislocation

Jaw dislocations often result from a combination of anatomical predisposition and specific actions that force the jaw beyond its normal range of motion.

• Excessive Mouth Opening: This is the most frequent cause. Activities that require a wide or prolonged opening of the mouth can lead to dislocation:
  • Yawning: A common scenario, especially if done forcefully or suddenly.
  • Laughing or Shouting: Particularly intense or prolonged episodes.
  • Vomiting: Forceful emesis can dislocate the jaw.
  • Dental Procedures: Prolonged periods with the mouth held wide open during dental work (e.g., wisdom tooth extraction, root canal) can fatigue the muscles and stretch the ligaments, increasing risk.
  • Singing: Especially high notes or prolonged vocalization.
• Trauma: A direct blow to the jaw or face can forcibly displace the condyle:
  • Sports Injuries: Impacts during contact sports.
  • Falls: Landing on the chin or side of the face.
  • Assaults: Direct punches to the jaw.
• Forceful Muscle Contraction:
  • Seizures: Involuntary, strong muscle contractions during a seizure can dislocate the jaw.
• Underlying Predisposing Factors: Some individuals are more susceptible due to anatomical or physiological characteristics:
  • Ligamentous Laxity: Conditions like Ehlers-Danlos syndrome or general joint hypermobility can lead to "loose" ligaments around the TMJ, making it easier for the joint to displace.
  • Shallow Glenoid Fossa or Flat Articular Eminence: Some people naturally have a less pronounced bony structure that normally prevents the condyle from sliding too far forward.
  • Previous Dislocation: Once dislocated, the ligaments and joint capsule can be stretched or damaged, significantly increasing the risk of recurrent dislocations.
  • Chronic TMJ Disorders: While not a direct cause, chronic issues like disc displacement or muscle imbalances can alter the mechanics of the joint, potentially predisposing it to dislocation.
  • Muscle Spasm: If the muscles that elevate the jaw (masseter, temporalis, medial pterygoid) go into spasm when the jaw is fully open, they can pull the condyle anteriorly and superiorly, locking it in place.

The Biomechanics of an Anterior Jaw Dislocation (Most Common)

Understanding the biomechanics explains why the jaw often gets stuck open.

1. Normal Opening: As you open your mouth, the mandibular condyle not only hinges but also slides forward (anteriorly) and slightly downward (inferiorly) along the articular eminence. This is a normal part of the TMJ's range of motion.
2. Over-Extension: If the mouth opens excessively wide, the condyle slides beyond the peak of the articular eminence.
3. Locking Mechanism: Once past the eminence, the strong elevator muscles of the jaw (masseter, temporalis, medial pterygoid), which are now in a stretched position, can spasm. This spasm pulls the condyle upward (superiorly) and further forward (anteriorly), effectively locking it in front of the articular eminence. The articular disc may also become displaced, contributing to the locking. The jaw is then unable to close because the condyle is physically obstructed from returning to the glenoid fossa.

Recognizing the Signs and Symptoms

A dislocated jaw is usually unmistakable and causes immediate distress.

• Inability to Close the Mouth: The most prominent symptom; the mouth remains wide open.
• Pain: Often severe and localized around the ear and jaw joint.
• Misalignment of the Jaw: The jaw may appear visibly shifted or protruded.
• Difficulty Speaking or Swallowing: Due to the open mouth position.
• Drooling: Inability to close the mouth leads to uncontrolled saliva flow.

What to Do If Your Jaw Dislocates

A dislocated jaw is a medical emergency that requires immediate professional attention.

• Seek Immediate Medical Attention: Do not attempt to reduce (put back in place) a dislocated jaw yourself. This should only be performed by a trained healthcare professional (e.g., emergency physician, oral surgeon, dentist). Incorrect manipulation can cause further damage to the joint, ligaments, or surrounding structures.
• Professional Reduction: A healthcare provider will use specific techniques to gently maneuver the condyle back into the glenoid fossa. This often involves applying downward and backward pressure on the jaw.
• Post-Reduction Care: After reduction, you may be advised to:
  • Limit Jaw Movement: Avoid wide opening for a period (e.g., soft diet, avoiding yawning).
  • Pain Management: Over-the-counter or prescription pain relievers.
  • Jaw Immobilization: In some cases, a bandage or splint may be used temporarily.

Prevention and Management

While not all dislocations can be prevented, especially those from trauma, individuals prone to dislocations or with predisposing factors can take steps to minimize risk.

• Avoid Extreme Jaw Opening: Be mindful during activities like yawning, laughing, or shouting.
• Support Your Jaw: During dental procedures, ask your dentist for a bite block or take breaks to rest your jaw.
• Manage TMJ Disorders: If you have a history of TMJ pain or dysfunction, work with a healthcare professional (dentist, oral surgeon, physical therapist) to manage your condition.
• Protective Gear: Wear appropriate mouthguards or facial protection during sports where jaw impact is a risk.
• Jaw Exercises: Under the guidance of a physical therapist, specific exercises can help strengthen the muscles around the TMJ and improve joint stability.