Osteonecrosis of the jaw with cancer treatment

Osteonecrosis of the jaw (ONJ) happens when part of the jawbone does not get enough blood and the bone dies. It most often affects the lower jaw (the mandible). ONJ is not common, but it can be serious. Knowing the signs and how to lower risk can help you protect your mouth health during cancer care.

What is osteonecrosis of the jaw?

ONJ means part of the jawbone loses blood supply and breaks down. You might see bone showing through the gums, or have pain and swelling. ONJ can be linked to cancer treatments, certain medicines, or dental injury or infection.

There are two common types related to cancer care:

Osteoradionecrosis – ONJ after radiation to the head or neck. Radiation can damage small blood vessels in the jaw.
Medication-related osteonecrosis of the jaw (MRONJ) – ONJ linked to medicines that affect bone turnover, such as bisphosphonates or denosumab.

What causes osteonecrosis of the jaw?

ONJ can be related to:

Radiation therapy to the head or neck (osteoradionecrosis).
Medicines that slow bone turnover, especially high doses used in cancer care: bisphosphonates and denosumab (MRONJ). Much lower doses are used for osteoporosis and carry a lower risk.
Dental injury, surgery, or infection – ONJ often starts after a tooth extraction, poorly fitting dentures, or untreated gum disease.

Other factors may raise risk, including poor oral hygiene, smoking or vaping, diabetes, steroid use, and some anti-angiogenic cancer medicines. The risk is higher with higher doses and longer time on bone-strengthening medicines.

How common is it?

ONJ is uncommon. Most people on these treatments never develop it. The chance is higher with cancer-dose bone medicines than with doses used for osteoporosis, and higher after radiation to the jaw area. Your oncology and dental teams can explain your personal risk.

What are the symptoms?

Areas of bone you can see or feel through the gums
Jaw or gum pain, swelling, or redness
Sores or ulcers on the gums that do not heal
Trouble opening your mouth fully (trismus)
Loose teeth or changes in your bite
Drainage, bad taste, or signs of infection around the bone

Sometimes only a small spot is affected. In other cases, it can spread to nearby tissue and skin.

How is ONJ diagnosed?

Your doctor or dentist will examine your mouth, teeth, and gums and ask about your treatments and dental history. They might order imaging tests to look at the jawbone:

X-rays to check bone changes
CT scans for detailed 3D pictures
MRI to show bone and soft tissue

These pictures help your team understand how much bone is involved and plan care.

How is ONJ treated?

Treatment focuses on controlling infection, easing symptoms, and removing dead bone when needed. Your plan depends on the size of the area and your overall health. Common approaches include:

Gentle mouth care and close follow-up with your dentist or oral surgeon
Antibiotic pills and/or an antibacterial mouth rinse, as prescribed
Removing dead bone (debridement) or smoothing sharp bone edges
Surgery to remove larger areas of affected bone, tissue, or skin if needed
Hyperbaric oxygen therapy for some people with osteoradionecrosis

If a medicine may be contributing, your team might discuss pausing or stopping it. This decision has risks and benefits. Do not stop any cancer or bone medicine without talking with your oncology team.

What can you do on your own?

Take good care of your mouth and teeth – Brush twice a day with a soft toothbrush and fluoride toothpaste. Floss daily or use interdental cleaners. If you wear dentures, make sure they fit well and remove them at night.
Keep your mouth moist – Sip water often. Ask about saliva substitutes if you have dry mouth from treatment.
Avoid smoking or vaping – These slow healing and raise infection risk. Ask your team for help quitting.
Manage blood sugar if you have diabetes.
Tell your dentist about all cancer treatments and medicines, especially bisphosphonates, denosumab, steroids, and targeted therapies.

How can ONJ be prevented?

The best prevention is a healthy mouth before and during treatment. Steps that often help include:

Get a dental checkup before starting head and neck radiation or high-dose bone medicines. Treat cavities, gum disease, and any infected teeth first.
Discuss dental extractions or implants with your team. If possible, complete needed surgeries before therapy starts and allow time to heal.
Limit invasive dental work during treatment if you can. If a procedure is necessary, your oncology and dental teams can plan it safely and may use antibiotics or rinses.
Keep regular cleanings and follow home care instructions.

Ask to see a dentist or oral medicine specialist experienced in caring for people with cancer.

Who is on your care team?

ONJ care is a team effort. Your team may include your medical oncologist, radiation oncologist, dentist or prosthodontist, oral and maxillofacial surgeon, and dental hygienist. They work together to reduce risk, watch for early signs, and treat problems quickly.

Questions to ask your team

What is my risk of osteonecrosis of the jaw with my treatment?
Should I have a dental exam before I start or continue therapy?
Are there dental procedures I should avoid or time carefully?
What symptoms should I watch for at home?
If I develop ONJ, what treatments might help me?

Key takeaways

ONJ is uncommon but can be serious. The lower jaw is affected most often.
Radiation to the head and neck and high-dose bone medicines (bisphosphonates or denosumab) raise risk.
Good dental care, quitting smoking, and planning dental work with your team lower your chances of ONJ.
Report symptoms early. Early care can prevent bigger problems.

References and helpful websites

Last reviewed: 2025-12-04