Guarding Your Smile During Cancer Treatment: A Guide to Understanding MRONJ

Introduction: What is MRONJ and Why Does it Matter?

For patients managing advanced cancer, bone health is a top priority. Doctors often prescribe medications to strengthen bones and prevent complications like fractures. While these treatments are highly effective, they can occasionally lead to a condition called Medication-Related Osteonecrosis of the Jaw (MRONJ).

MRONJ occurs when the jawbone does not heal properly after a minor injury or dental procedure, leading to bone exposure. To be formally diagnosed, three specific criteria must be met:

1. Medication History: Current or previous treatment with a bone-modifying agent (BMA) or certain angiogenic inhibitors (drugs that restrict blood vessel growth).
2. Persistent Symptoms: Exposed bone—or an opening (fistula) that leads to the bone—appearing inside the mouth or on the skin of the face (extraoral) that has not healed for at least eight weeks.
3. No Radiation History: No history of radiation therapy to the jaw and no signs of cancer spreading directly to the jawbones.

Fast Facts

• Incidence: MRONJ affects approximately 1% to 9% of patients with advanced cancer receiving bone-modifying agents.
• Risk and Time: The risk is not constant; for some medications, the likelihood of developing MRONJ increases the longer you are on the treatment.
• Common Sites: It occurs in both the upper and lower jaw, though it is more frequently seen in the lower jaw (mandible).

The Culprits: Medications and Risk Factors

MRONJ is primarily associated with medications used to manage bone metastases and multiple myeloma. While Bone-Modifying Agents (BMAs) are the most common cause, other drugs like angiogenic inhibitors (e.g., bevacizumab or thalidomide) can also increase risk, especially when used in combination with BMAs.

Common Medications and Reported Frequency

Medication	Common Indication	Frequency of MRONJ
Pamidronate	Bone metastases; Multiple myeloma	3.2% – 5.0%
Zoledronic acid	Bone metastases; Multiple myeloma	1.0% – 8.0%
Denosumab	Bone metastases	0.7% – 6.9%*

*Note: The 6.9% figure is associated with long-term therapy. The risk for Denosumab increases over time, starting at roughly 1.1% in the first year and rising to 4.6% per year after the second year of treatment.

Modifiable Risk Factors

While you cannot change your medication needs, you can reduce your risk by managing these factors:

• Tobacco Use: Smoking significantly hinders the mouth’s ability to heal.
• Uncontrolled Diabetes: High blood sugar levels can complicate oral health and recovery.
• Ill-fitting Dentures: Devices that rub or cause trauma to the gums can lead to bone exposure.
• Timing of Dental Care: While "Invasive Dental Procedures" (like extractions) are triggers, the risk is "modifiable" by ensuring necessary surgeries are performed before you start medication.

Prevention: The Power of the "Dental First" Strategy

The "Dental First" strategy is the most effective way to protect your jaw. In a nonurgent setting—where your cancer treatment does not need to start immediately to manage a crisis like acute hypercalcemia—prevention is the gold standard.

Comprehensive Assessment Before your first dose of a BMA, you should have a full dental exam, including X-rays. This identifies potential problems, such as infections or failing teeth, that could cause trouble later.

Coordination of Care Your oncologist and dentist must work together. Any medically necessary surgeries should be completed, and your gums should be fully healed, before starting BMA therapy. Once treatment begins, regular dental check-ups (typically every six months) are vital.

Elective Procedures While on an oncologic dose of a BMA, elective surgeries involving the bone—such as dental implants or non-essential extractions—should generally be avoided.

Your Daily Defense: The MASCC/ISOO Oral Care Plan

Meticulous hygiene is your best shield. This checklist, based on international guidelines, should be your daily routine:

Brushing

• Use a small, ultra-soft-headed toothbrush. Ultrasonic toothbrushes are also acceptable.
• Use prescription-strength fluoride toothpaste. Spit out the foam but do not rinse with water afterward to allow the fluoride to protect your teeth.
• Brush within 30 minutes after eating and before bed. Include the tongue by brushing it gently from back to front.
• Soften the brush in hot water before use and air-dry it afterward.

Flossing

• Floss at least once daily. Waxed floss is often gentler on the gums.

Rinsing

• Rinse several times a day with a Bland Rinse.
• Recipe: Mix 1 teaspoon of baking soda and 1 teaspoon of salt (use non-iodized salt if available) in 4 cups of water.
• Avoid mouthwashes with alcohol, as they can dry out and irritate the mouth.

Lip Care

• Moisturize with products containing beeswax, cocoa butter, or lanolin. Avoid petroleum-based products.

Denture Care

• Remove dentures before brushing and clean them after every meal.
• Leave dentures out for at least 8 hours a day (e.g., while sleeping) and soak them in a rinsing solution.

Staging and Management: Understanding the Path to Healing

If MRONJ develops, specialists use a staging system to determine the best treatment.

• Stage 0 (At Risk): You may have symptoms like dull bone pain or "numbness," but there is no exposed bone yet.
• Stage 1: Bone is exposed but the area is painless and shows no signs of infection.
• Stage 2: Exposed bone is accompanied by pain, redness, or swelling, indicating an active infection.
• Stage 3: This is the most severe stage, involving extensive bone exposure that may cause jaw fractures or affect your ability to eat or speak.

When to Call Your Doctor

Contact your care team immediately if you notice:

• Unexplained pain in the jaw or teeth.
• Swelling or redness in the gums that doesn't go away.
• A feeling of numbness or "heaviness" in the jaw.
• Any area where you can feel or see bone.

Management Philosophy

The first approach is almost always Conservative Measures. This includes antimicrobial rinses and antibiotics to control infection. A specialist may gently remove small, sharp "spicules" of bone if they are irritating your tongue or cheeks.

Aggressive Surgical Intervention is considered "refractory" care. If the condition does not improve with conservative steps and begins to severely impact your quality of life or function, a surgeon may remove sections of necrotic bone. Surgery is generally not recommended for bone exposure that is not causing symptoms.

The "Drug Holiday" Question: There is currently insufficient evidence to prove that stopping your cancer medication (a "drug holiday") helps MRONJ heal. This is a complex medical decision made case-by-case by your oncologist and dental team.

The Multidisciplinary Team: Who is on Your Side?

You are supported by a diverse group of experts:

• Medical Oncologists: They manage your cancer therapy and coordinate the timing of your bone medications.
• Community Dentists: They provide the initial screenings and your regular, long-term preventive care.
• Dental Specialists: This group includes Oral Surgeons, Periodontists, Oral Medicine Specialists, and Oral Pathologists who have advanced training in diagnosing and treating bone disorders.

Questions to Ask Your Doctor

• Is an Oral Medicine Specialist available to review my case?
• Are there any "angiogenic inhibitors" in my treatment plan that I should tell my dentist about?
• Should I delay my first BMA dose until my dental work is fully healed?
• If I need an emergency extraction, how will we coordinate my medication schedule?

Conclusion: Key Takeaways for the Path Ahead

Protecting your smile is a vital part of your cancer journey. By staying proactive, you can significantly reduce the impact of MRONJ on your life.

The Bottom Line:

1. See a dentist first: Complete all necessary dental work before starting bone-modifying agents.
2. Maintain a routine: Use the bland rinse and a soft toothbrush daily.
3. Monitor your health: Keep diabetes controlled and seek support to quit tobacco.
4. Communicate: Ensure your oncologist and dental specialists are in constant contact.
5. Act fast: Report any new jaw pain, swelling, or numbness immediately.

For more resources and patient-focused information, visit www.cancer.net. This guide is based on the clinical practice guidelines developed by ASCO, MASCC, and ISOO.