Osteonecrosis of the jaw (ONJ) is a serious but uncommon condition where jaw bone loses its blood supply, leading to bone death and exposure in the mouth. It is particularly relevant to tooth extraction procedures, as it can occur when the extraction site fails to heal properly, leaving the bone exposed. While rare, ONJ can significantly affect a person’s quality of life, often causing discomfort and requiring careful management.
Understanding Osteonecrosis of the Jaw
ONJ involves the death of a section of bone in the upper (maxilla) or lower (mandible) jaw that becomes exposed in the mouth and does not heal. This occurs when the affected bone does not receive sufficient blood flow, leading to bone cell death. While it can manifest spontaneously, ONJ is often observed following dental procedures like tooth extraction, where gum tissue fails to cover the exposed bone, preventing proper healing.
Symptoms of ONJ can vary, with some individuals experiencing no symptoms initially. As the condition progresses, a person might notice pain, swelling of soft tissues and gums, or a feeling of numbness or “heavy jaw.” Other signs include pus or drainage, visible exposed bone, loose teeth, and difficulty chewing. For a diagnosis of ONJ, these symptoms typically persist for at least eight weeks.
Factors Increasing Risk
Several factors can increase an individual’s susceptibility to developing ONJ, especially after a tooth extraction.
Medications
Certain medications are a primary concern. Bisphosphonates, such as alendronate (Fosamax) or zoledronic acid (Zometa), prescribed for osteoporosis and bone fractures (especially in cancer patients), inhibit osteoclasts, slowing bone turnover. This suppression impairs the jawbone’s ability to repair itself after trauma, such as a tooth extraction, leading to ONJ.
Denosumab (e.g., Prolia, Xgeva) is another anti-resorptive medication that increases ONJ risk. Like bisphosphonates, it reduces bone resorption and can hinder the jaw’s healing capacity after dental procedures. The risk with these medications increases with higher doses and longer durations of use. Patients receiving intravenous forms for cancer treatment are at a higher risk than those taking lower oral doses for osteoporosis.
Health Conditions
Underlying health conditions also play a role. Patients with cancer, particularly those with multiple myeloma or metastatic bone disease, face an elevated risk. Diabetes mellitus is another contributing factor, as it can impair bone quality through mechanisms like microvascular ischemia, reduced bone remodeling, and increased inflammation, making the jawbone more vulnerable.
Other Factors
Prior radiation therapy to the head and neck area is a significant risk factor, leading to osteoradionecrosis. Radiation damages bone blood vessels, reducing its ability to heal from infection, trauma, or surgery. The risk increases with radiation doses greater than 60 grays (Gy). Damage or trauma to the jaw after radiation therapy, even years later, can also elevate the risk. Other factors include smoking, which speeds up bone loss, poor oral hygiene, and the use of systemic corticosteroids.
Diagnosis and Management
Diagnosing ONJ primarily relies on a thorough clinical examination. A healthcare provider will visually inspect the mouth for exposed bone that has persisted for at least eight weeks, noting any associated pain, swelling, or signs of infection. Imaging studies then support this assessment to determine the extent of bone involvement.
Imaging Studies
X-rays: Conventional X-rays, like panoramic radiographs, can show changes in bone structure and density. However, they may miss early-stage ONJ, as significant bone destruction is needed for visible changes.
CT Scans: Computed tomography (CT) and cone-beam CT (CBCT) offer higher resolution images to reveal lesions and bone changes.
MRI: Magnetic Resonance Imaging (MRI) is a valuable tool for detecting early bone marrow changes and inflammation, providing superior soft tissue contrast.
The management of ONJ focuses on controlling pain, preventing infection, and limiting bone death progression.
Conservative Management
Conservative management is often the initial approach. This involves oral antimicrobial rinses, systemic antibiotics to combat infection, and pain medication. Gentle debridement, the scraping away of exposed dead bone, can also be performed to promote healing.
Surgical Management
Surgical management becomes necessary in more advanced cases, such as for extensive disease, uncontrolled pain, or persistent infection. Procedures can range from removing mobile segments of dead bone (sequestrectomy) to more extensive resections. Jaw reconstruction using bone grafts may be considered after affected bone removal.
Preventive Measures and Patient Outlook
Minimizing the risk of ONJ, especially around tooth extractions, involves several proactive measures. Patients should inform their dentist about all medications they are taking, particularly bisphosphonates and denosumab, and their complete medical history. Dentists may consider less invasive procedures, such as a root canal, if a tooth can be saved.
For patients on oral bisphosphonates for over four years or with additional risk factors, a temporary discontinuation of medication (drug holiday) for about two months before a dental procedure may be considered. However, for individuals on intravenous bisphosphonates or denosumab, drug holidays are generally not recommended due to potential risks and limited evidence of benefit. Comprehensive preventive dental care, including treating active oral infections and maintaining excellent oral hygiene, is more effective.
During and after a tooth extraction, meticulous surgical technique that minimizes bone trauma is important. Adherence to post-operative instructions, including proper oral hygiene and dietary modifications, is necessary for optimal healing. Regular dental check-ups are also advised to monitor oral health.
While ONJ is a serious condition, it is manageable. Early detection and appropriate treatment can help stabilize the condition and prevent worsening, preserving the jawbone and teeth. Many individuals with early stages of ONJ experience improvement with conservative treatments. Patients may need ongoing care to manage symptoms and maintain oral health, but with proper intervention, the condition can often be controlled.