What is osteonecrosis of the jaw?

Medication-Related Osteonecrosis of the Jaw: A Simple Explanation

Medication-related osteonecrosis of the jaw (MRONJ) is a serious condition where bone tissue in the jaw dies and becomes exposed, failing to heal for 8 weeks or longer, caused by certain medications that affect bone metabolism. 1

What Is Osteonecrosis of the Jaw?

Osteonecrosis of the jaw is characterized by:

• Dead (necrotic) bone in the jaw area (maxilla or mandible) that becomes exposed
• Bone that can be probed through an intraoral or extraoral fistula
• Failure to heal for 8 weeks or longer
• Occurs in patients who have taken specific medications but have no history of radiation therapy to the jaw area 1

The condition can cause significant pain, infection, and decreased quality of life. It affects the mandible (lower jaw) more commonly than the maxilla (upper jaw) in a 2:1 ratio. 2

Medications That Cause MRONJ

MRONJ is primarily associated with:

1. Bone-modifying agents (BMAs):

   • Bisphosphonates (like alendronate, zoledronic acid)
   • Denosumab

2. Angiogenic inhibitors (medications that block the formation of new blood vessels) 1

The risk is significantly higher with:

• Intravenous forms of these medications (used for cancer treatment)
• Long-term use
• Higher doses 1, 3, 4

Risk Factors

Several factors increase the risk of developing MRONJ:

• Dental procedures: About 60% of cases occur after dental surgical procedures, particularly tooth extractions 2
• Poor oral health
• Ill-fitting dentures
• Uncontrolled diabetes mellitus
• Tobacco use
• Cancer diagnosis (especially multiple myeloma and metastatic cancer)
• Concurrent chemotherapy or corticosteroid use 1, 4

Diagnosis

MRONJ is diagnosed when all three of these criteria are present:

1. Current or previous treatment with a bone-modifying agent or angiogenic inhibitor
2. Exposed bone or bone that can be probed through a fistula in the jaw area that has persisted for more than 8 weeks
3. No history of radiation therapy to the jaws 1

Staging System

MRONJ is classified into stages to guide treatment:

• At Risk: No apparent bone necrosis but patient has taken relevant medications
• Increased Risk: No visible bone necrosis but nonspecific symptoms and radiographic changes
• Stage 1: Exposed/probeable bone without symptoms or infection
• Stage 2: Exposed/probeable bone with pain and infection
• Stage 3: Advanced condition with complications like pathologic fracture, extraoral fistula, or extensive bone involvement 1

Prevention

Prevention is crucial and includes:

• Dental assessment before starting BMAs: Complete dental exam including X-rays
• Addressing dental issues: Treating existing dental problems before starting medication
• Regular dental follow-up: Every 6 months after starting BMAs
• Avoiding elective dental surgery: Non-essential dental procedures should be avoided during treatment with BMAs 1

Treatment

Treatment depends on the stage but generally includes:

• Conservative approaches first: Antibacterial mouth rinses, pain control, and antibiotics for infection
• Limited surgical intervention: Removal of loose bone fragments without exposing healthy bone
• Regular follow-up: Every 8 weeks with communication between dental specialist and oncologist
• Patient education: About maintaining good oral hygiene and recognizing symptoms 1

For advanced cases, more extensive surgical debridement may be necessary, though this is approached cautiously. 1, 5

Important Considerations

• The risk of MRONJ with oral bisphosphonates (used for osteoporosis) is much lower (estimated at less than 1%) than with intravenous forms used for cancer treatment (1-9%) 1, 6
• Discontinuing bisphosphonates may not immediately improve healing due to their long half-life in bone tissue 1
• Specialized care from professionals experienced with MRONJ is essential for optimal outcomes 7

Finding Specialized Care

Patients can locate specialists through:

• American Dental Education Association dental schools directory
• American Academy of Oral Medicine
• American Association of Oral and Maxillofacial Surgeons 7

MRONJ requires a coordinated approach between oncologists, dentists, and oral surgeons to ensure the best possible outcomes for patients affected by this challenging condition.