Osteonecrosis of the Jaw (ONJ)

Osteonecrosis of the jaw (ONJ) is a rare but serious condition that causes bone cells in your jawbone to die. It may make parts of your jawbone poke through an opening in your gums. Because blood can’t reach the exposed area, more of the bone dies.

“Osteonecrosis” (pronounced “oss-tee-oh-neh-kroh-sis”) is the medical term for bone death. “Osteo” means bone, and “necrosis” means death. When it happens, it’s usually as a rare side effect of taking cancer-fighting medicines that affect your bones. In this context, it’s also called medication-related osteonecrosis of the jaw (MRONJ). Issues usually show up after major dental work, like having a tooth pulled.

The bone in your jaw can also die because of damage from radiation therapy to treat head and neck cancers. This is called osteoradionecrosis. It’s similar to, but not quite the same as, ONJ.

Symptoms of jaw osteonecrosis

If you recently had a dental procedure and develop ONJ, you may have pain on the side of your mouth where the dental work took place. But some people don’t have symptoms at first.

The most obvious sign is an area of exposed jawbone that doesn’t heal. Usually, it’s the lower jawbone. But it can impact your upper jaw, too. Other signs include:

• Jaw pain
• Loose teeth
• Mouth sores
• Swollen gums
• Signs of an infection, like warmth, redness or a pus-like discharge in your gums and mouth

ONJ causes

This condition mostly happens in people taking high doses of cancer medicines that impact the bone repair process. These are called antiresorptive medicines. They can reduce cancer symptoms, like bone pain, and even slow tumor growth in your bones. But these meds also increase your risk of medication-related osteonecrosis of the jaw (MRONJ).

ONJ tends to occur after dental procedures, like having a tooth pulled or getting a dental implant or bone graft that leaves some of your jawbone exposed. In osteonecrosis of the jaw, your gum tissue doesn’t heal afterward, and your jawbone is left exposed. The exposed bone doesn’t receive blood flow. As a result, the bone cells die.

Rarely, people develop this condition for no apparent reason.

Risk factors

The risk increases if you’re taking bisphosphonates or denosumab to manage cancer that’s spread to your bones. These IV medicines slow bone loss and increase bone strength in people with cancer that’s in their bones. 

You may also take lower doses of these medicines in pill form for osteoporosis. But studies show that these low-dose forms don’t pose the same risks of ONJ as the kind you get for cancer treatment.

Other risk factors include:

• Chemotherapy
• Diabetes
• Facial fracture or trauma
• Gum disease, including periodontitis
• Long-term use of corticosteroids
• Taking angiogenic inhibitors (cancer medicine that prevents new blood vessels from forming) while also taking bisphosphonates
• Wearing dentures, especially if they don’t fit well

How doctors diagnose this condition

Your dentist or oral surgeon may diagnose ONJ based on your symptoms. They may also do imaging procedures, like a dental X-ray. An exposed jawbone that persists for more than eight weeks indicates ONJ.

It’s important to see your dentist as soon as you think there’s a problem, especially if you’re at high risk for ONJ. Early diagnosis and treatment may save your jaw and teeth.

What are the stages of osteonecrosis of the jaw?

There are four stages, ranging from 0 (least severe) to 3 (most severe). Your healthcare provider will determine the disease stage at the time of diagnosis.

Stages of ONJ include:

• Stage 0: You receive IV bisphosphonate treatments and have jaw pain. But you don’t have exposed bone or other symptoms.
• Stage 1: Your jawbone is exposed, but you don’t have pain or other symptoms.
• Stage 2: Your jawbone is exposed and you have symptoms, including pain, swollen gums and signs of infection.
• Stage 3: You have all the symptoms of stage 2 ONJ, as well as osteonecrosis in your sinuses and other parts of your face. The disease extends beyond your tooth socket.

How is it treated?

Oral and maxillofacial surgeons treat ONJ. These dental professionals specialize in managing complex dental conditions that affect your teeth and jaws.

No matter the stage, they’ll review your risk factors and help you change any that are in your control. They’ll also recommend treatments that can ease symptoms, including:

• Antibiotics
• Antiseptic mouth rinses
• Pain relievers

Other treatments depend on the stage of the disease.

Treatment for stage 0

Your provider will watch you closely for changes. They’ll educate you about changes you may need to make to protect your teeth and jawbone.

Treatment for stage 1

Your provider will scrape or scrub away the exposed dead bone cells. This treatment — called debridement — prevents more bone loss and helps your gums heal over your bone.

Treatment for stage 2 and stage 3

You’ll need surgery to remove the section of dead jawbone and any tooth that touches that section of your jaw. Your surgeon will also remove a small amount of healthy tissue to ensure there aren’t any lingering diseased bone cells.

If you have stage 3 ONJ, you may need surgery to remove dead bone that extends into your nasal passages.

When should I see my healthcare provider?

You’ll see your dental care provider during regular follow-up visits, usually around every two to six months. It’s important to follow the schedule they recommend.

What can I expect if I have this condition?

Early detection and treatment can keep ONJ from getting worse and help preserve your jawbone. Most people with early-stage ONJ get better without surgery. Once the condition worsens, you’re at risk of losing sections of your jawbone, as well as some of your teeth.

​Can this be prevented?

Having a complete dental assessment before starting antiresorptive medicines for cancer can greatly reduce your risk of ONJ. In some cases, you may be able to delay starting antiresorptive medicine until you get all dental issues addressed.

If you’re already taking them, it’s very important that your dentist or oral surgeon knows. They may be able to treat your dental issue with less invasive procedures. For example, if you need to have a tooth removed, your dentist may do a root canal instead of pulling the tooth. They may prescribe antibiotics beforehand to reduce the risk of infection.

In the meantime, make caring for your teeth a priority. Good dental hygiene is important for everyone. But it’s essential if you’re at risk of ONJ.

What’s the difference between osteonecrosis of the jaw and osteomyelitis?

Both ONJ and osteomyelitis cause painful bone loss. But osteomyelitis is a bone infection. Bacteria or fungi cause it. When the infection affects your jawbone, you may have symptoms similar to ONJ. But osteomyelitis often causes a fever. ONJ doesn’t. Healthcare providers use blood tests to check for signs of infection and diagnose osteomyelitis.