The temporomandibular joint (TMJ) is the complex joint connecting your jawbone (mandible) to the skull’s temporal bone, located just in front of your ears. This joint enables everyday movements such as chewing, speaking, and yawning. “Closed lock” TMJ refers to a specific, often painful condition where the jaw’s movement becomes severely restricted, making it difficult to open the mouth fully.
What is Closed Lock TMJ?
Closed lock TMJ is a functional disorder of the temporomandibular joint. It occurs when the articular disc, a small piece of cartilage that cushions the joint, becomes displaced forward (anteriorly) from its usual position. When the jaw attempts to open, this displaced disc does not return to its proper place between the condyle (the rounded end of the jawbone) and the temporal bone, effectively blocking the condyle’s movement. This condition is also known as “disc displacement without reduction with limited opening”.
The primary characteristic of closed lock TMJ is a marked limitation in the ability to open the mouth. This restriction is often accompanied by pain localized to the area in front of the ear, which can be sharp and sudden, especially during attempted jaw movement. While some people with TMJ issues experience clicking or popping sounds, these noises typically disappear once the jaw becomes locked because the disc is no longer moving in and out of place. The jaw may also deviate to the affected side when attempting to open, and the maximum mouth opening might be less than 40 millimeters.
Why Closed Lock TMJ Occurs
Several factors can contribute to closed lock TMJ. Trauma to the lower jaw is a common cause of disc displacement, which can lead to a closed lock. This can include direct impacts or injuries to the jaw or head.
Chronic teeth clenching or grinding, known as bruxism, can also contribute to disc displacement. The constant stress and force on the joint from these habits can make the disc more prone to displacement. Hypermobility, or excessive flexibility of the jaw joint, can also predispose individuals to disc displacement as the ligaments supporting the disc may be looser, allowing it to move out of position more easily.
Degenerative joint diseases, such as osteoarthritis, can affect the TMJ, leading to changes in the joint’s structure and potentially causing disc displacement. Systemic connective tissue disorders can also increase susceptibility to closed lock TMJ.
How Closed Lock TMJ is Diagnosed and Treated
Diagnosing closed lock TMJ begins with a thorough clinical examination. A healthcare professional will assess the jaw’s range of motion, listen for joint sounds, and gently press on areas around the jaw to identify tenderness. During this examination, a limited maximum mouth opening, often less than 40 millimeters, and a deviation of the jaw to the affected side during opening can be observed. Applying passive force to the jaw does not significantly increase the range of opening.
To confirm the diagnosis and visualize the joint’s internal structures, imaging techniques are employed. Magnetic Resonance Imaging (MRI) is considered the most informative imaging method for TMJ conditions because it allows for a detailed assessment of the disc’s position and surrounding tissues. An MRI can confirm if the disc is displaced anteriorly and if it remains so even when the mouth is open. Other imaging, such as dental X-rays or CT scans, may be used to rule out other issues or examine bone changes within the joint.
Treatment for closed lock TMJ begins with conservative approaches, aiming to reduce pain and restore jaw function. Initial management may involve resting the jaw, adhering to a soft diet, and using pain relievers and anti-inflammatory medications like NSAIDs to manage discomfort. Physical therapy plays a role in treatment, incorporating jaw exercises and mobilization techniques to improve range of motion and reduce muscle tension. Oral appliances, such as splints or orthotics, are sometimes used to help reposition the jaw or protect the joint structures.
If conservative methods are not sufficient, other interventions may be considered. Injections, such as corticosteroids or hyaluronic acid, can be administered directly into the joint to reduce inflammation and improve lubrication. Minimally invasive procedures like arthrocentesis or arthroscopy may be performed. In rare and severe cases where other treatments have failed and a structural issue persists, open-joint surgery might be considered to repair or replace parts of the joint. However, surgical interventions are generally a last resort due to their increased risks compared to less invasive options.
Managing Closed Lock TMJ and Recovery
Managing closed lock TMJ and promoting recovery involves a combination of self-care practices and adherence to professional guidance. Applying warm compresses to the jaw area for 10-15 minutes can help relax muscles and reduce spasms. Gentle jaw exercises, as recommended by a healthcare professional, can also aid in improving mobility over time. Stress reduction techniques, such as meditation or relaxation exercises, may also be beneficial, as stress can contribute to jaw tension and bruxism.
Dietary modifications are also helpful during recovery. Sticking to soft foods reduces the strain on the jaw joint, allowing it to rest and heal. Examples include mashed potatoes, smoothies, and cooked vegetables.
The prognosis for closed lock TMJ can vary. Some cases may resolve relatively quickly, while others might require more prolonged management. The best chance for unlocking the jaw often occurs within the first few days of the lock. Adherence to the prescribed treatment plan, whether it involves conservative therapies or more advanced procedures, is important for optimizing recovery and improving long-term outcomes.