Condylar resorption is a condition where the bone in the temporomandibular joints (TMJs) experiences a progressive breakdown and loss. The condyles are rounded ends of the lower jawbone, or mandible, that connect to the skull, forming the TMJ. The condition causes the lower jaw to shrink and pull back, which can occur rapidly over months or develop slowly over years.
Identifying the Condition
Recognizing condylar resorption often begins with observing changes in facial appearance and jaw function. A noticeable symptom is a change in the way the teeth meet, such as an emerging open bite where the front teeth no longer touch, or an overbite. Individuals may also experience a receding chin, which becomes less defined as the jaw retracts.
Jaw pain, headaches, and sounds like clicking, popping, or grinding within the jaw joints are also common indications. Limited jaw movement can make activities such as eating or talking difficult. A specialist, often an oral and maxillofacial surgeon or an orthodontist, typically diagnoses the condition.
The diagnostic process involves a thorough clinical evaluation of symptoms and a physical examination of the jaw and facial structures. Advanced imaging techniques are then employed to visualize the bone structure of the condyles. Cone Beam Computed Tomography (CBCT) scans are considered the primary method for clearly showing bone loss and changes in condylar shape and volume.
Other imaging, such as MRI, may be used to assess soft tissues like the articular disc within the TMJ and to differentiate condylar resorption from other conditions. Sometimes, serial scans taken over time are used to monitor the progression of bone loss and determine if the condition is active.
Associated Risk Factors and Causes
The exact cause of condylar resorption is not fully understood, and in many instances, it is classified as idiopathic, meaning it has no known origin. However, several factors are associated with its development. There is a strong connection to hormonal influences, which explains why the condition is observed more frequently in teenage girls and young women, often in a ratio of 9 females to 1 male.
Estrogen receptors are present in the TMJ, and elevated levels of these receptors have been identified in individuals with condylar resorption, suggesting a link to bone metabolism and joint stability. Systemic autoimmune or inflammatory conditions, such as rheumatoid arthritis, scleroderma, and lupus, are also associated with condylar resorption. These conditions can lead to inflammation in the jaw joints, contributing to bone breakdown.
Other potential contributing factors include trauma to the jaw from injuries or sports activities. Previous orthodontic treatments or jaw surgeries have also been mentioned as potential influences due to increased mechanical stress on the joint.
The Progression of Jaw Changes
As condylar resorption progresses, the consistent loss of bone height in the condyles leads to observable structural and aesthetic changes in the lower face. The lower jaw, or mandible, rotates downwards and backwards due to this loss of support. This rotational effect alters the overall facial profile. The lower face can appear shorter, and the chin may become more prominent or recede further, depending on the specific rotation.
Medical and Surgical Interventions
Treatment for condylar resorption aims to halt the progression of bone loss, restore jaw function, and correct any resulting facial or bite deformities. Initial conservative approaches focus on managing symptoms and stabilizing the joint. This may involve the use of custom oral splints, also known as orthotics, which can help reposition the jaw and reduce stress on the condyles.
Medications, such as anti-inflammatory drugs, are sometimes used to help slow the resorption process and manage pain or inflammation within the joint. For more definitive solutions, surgical interventions are considered, particularly once the condylar resorption has stabilized.
One surgical option is orthognathic surgery, which involves repositioning the jawbones to correct bite discrepancies and facial asymmetry. In cases of severe condylar damage, total temporomandibular joint replacement may be necessary. This procedure involves removing the diseased condyles and replacing them with custom-fitted prosthetic joints. Total joint replacement is often performed in conjunction with orthognathic surgery to achieve a stable bite and improved facial balance.