MRONJ: What Cancer Patients on Bisphosphonates and Denosumab Need to Know

What MRONJ Is and Why the Name Changed

Medication-related osteonecrosis of the jaw is a condition where a portion of exposed jawbone fails to heal after injury or spontaneously, in patients on certain medications. It was originally described as bisphosphonate-related osteonecrosis (BRONJ) in the early 2000s, when bisphosphonates were the primary implicated drug class. The name changed to MRONJ once other agents, particularly denosumab and some anti-angiogenic cancer drugs, were shown to carry similar risk.

The clinical picture is exposed bone in the jaw, most often the mandible, that persists for at least 8 weeks in a patient with a relevant medication history and no head or neck radiation. It can range from a small area of exposed bone with minimal symptoms to a large necrotic lesion with pain, infection, and functional impairment.

Who Is Actually at Risk

The MRONJ risk profile depends on the drug, dose, duration, and reason for treatment.

• Cancer patients on IV bisphosphonates (zoledronic acid, brand name Zometa) for bone metastases or multiple myeloma face the highest baseline risk, roughly 1 to 15 percent depending on duration.
• Cancer patients on denosumab (Xgeva) for bone metastases face similar or slightly higher risk than IV bisphosphonates.
• Osteoporosis patients on oral bisphosphonates (Fosamax, Boniva, Actonel) or lower-dose denosumab (Prolia) face much lower risk, typically well under 1 percent.
• Patients on anti-angiogenic agents (bevacizumab, sunitinib, and others) can be at elevated risk, particularly in combination with bone-modifying drugs.

Duration also matters. Risk increases with longer time on therapy. Patients who have been on high-dose therapy for several years are in a different risk category from someone starting a first infusion.

How the Risk Adds Up

MRONJ risk is not a single number. It compounds from several factors:

• Drug class and dose (as above).
• Duration on the medication.
• Recent or planned invasive dental procedures, especially extractions.
• Presence of active dental infection or advanced gum disease.
• Denture-related trauma or poorly fitting appliances.
• Systemic factors including diabetes, smoking, corticosteroid use, and chemotherapy.

The interaction between drug exposure and dental trauma is where most MRONJ cases actually occur. This is why timing dental care around bone-modifying therapy matters so much.

The Dental Decisions That Matter Most

Some dental care is straightforward and safe for patients on bone-modifying drugs. Some requires careful planning. A dental oncology consultation helps sort which is which.

• Preventive care is safe and important. Cleanings, exams, X-rays, and fluoride treatments carry no meaningful MRONJ risk and are strongly recommended. Patients on bone-modifying drugs should see the dentist more often, not less.
• Fillings, crowns, and root canals are generally safe. These do not disturb bone significantly. Root canal followed by a crown is often preferred over extraction for a failing tooth in this population.
• Extractions require planning. When unavoidable, extractions should be planned and coordinated with the oncology team. Timing, technique, and postoperative care all affect risk.
• Implants require case-by-case evaluation. Implants are not automatically off the table for patients on bone-modifying drugs, but the risk-benefit conversation is more complex.
• Poorly fitting dentures should be addressed. Chronic trauma from an ill-fitting appliance is a documented MRONJ trigger and is easily addressed.

Before Starting Bone-Modifying Therapy

If you are about to start IV bisphosphonates or denosumab for cancer, the most valuable dental step is a comprehensive evaluation before the first dose. The goal is to identify and address any dental problems that might otherwise need invasive treatment later.

This visit typically includes a thorough exam, imaging, treatment of any active decay or gum disease, and extraction of any teeth with a poor long-term prognosis. Small problems dealt with now avoid larger surgical decisions later.

If your oncology team is starting therapy urgently and there is not time for a full dental workup, an abbreviated assessment focused on urgent findings is still worth doing.

If You Are Already Diagnosed With MRONJ

MRONJ management has changed substantially in the last decade. The old approach was largely conservative and often left patients with chronic exposed bone for years. Current management is more active and, for many patients, curative.

Treatment options depend on stage and extent but can include antimicrobial mouth rinses, targeted antibiotics for infection, careful debridement of necrotic bone, and in more advanced cases, surgical resection with reconstruction. Adjunctive therapies like teriparatide and hyperbaric oxygen have specific roles in selected cases.

A referral to a dental oncologist or oral and maxillofacial surgeon experienced with MRONJ is the right step if you have been diagnosed. General dentistry is not the right setting for this care.

Coordinating With Your Oncology Team

MRONJ prevention and management work best when the dental and oncology teams are actively coordinating. That coordination includes sharing which drug you are on and for how long, whether therapy can be temporarily paused around invasive procedures if clinically appropriate (this is a decision your oncologist makes, not your dentist), and how any dental findings should be handled in the context of your overall treatment plan.

Ask your oncology team whether they have a dental oncology referral relationship. Many do. If they do not, ask us to communicate directly.