Osteonecrosis of the jaw

Osteonecrosis of the jaw (ONJ) is a rare condition, the cause of which is not entirely known. It involves the loss or breakdown of a small segment of the jaw bone.

It can be a serious condition and may cause difficult to treat pain. It appears to be related to long-term treatment with drugs used to treat bone disease in myeloma and other cancers, which are known as bisphosphonates, particularly in the intravenous (IV) type. It is not yet known how often ONJ occurs in myeloma, but from available reports, the incidence in patients on intravenous (IV) bisphosphonates can range between 1-15%. In Australia, the incidence is probably less than that.

What is the connection between bisphosphonates and ONJ?

The exact reasons why ONJ is linked to long-term use of some bisphosphonates are not fully understood. We know that bisphosphonates work by binding to calcium and reducing the activity of the cells that cause bone breakdown in myeloma (osteoclasts). It has been suggested that ONJ occurs because bisphosphonates disrupt normal bone remodelling, and affect the healing process after trauma or just every day injury that occurs to the tissues of the mouth. The bones of the jaw seem to be particularly prone to osteonecrosis. In the mouth, the bone is only covered by a small layer of tissue so it can become more easily exposed, particularly at the site of invasive dental procedures, and for this reason, people with otherwise poor dental health appear to be at greater risk.

Risk factors for ONJ

There is a risk of ONJ for people with myeloma on regular, monthly administration of IV bisphosphonates.

The risk of ONJ occurring in myeloma is also closely related with:

  • removal of teeth while undergoing bisphosphonate treatment (this is the most common reported incident occurring before diagnosis of ONJ)
  • long time use of bisphosphonates (>12 months)
  • age (in the elderly)
  • a history of poor dental health
  • smoking
  • diabetes
  • poor fitting oral appliances.

What are the symptoms of ONJ?

Symptoms and signs can include:

  • pain or swelling in the mouth
  • non-healing of a tooth socket after removal of teeth
  • loosening of teeth
  • an area of exposed bone in the mouth
  • poor healing or infection of the gums
  • numbness or the feeling of heaviness in the jaw
  • discharge of pus.

If you experience any of these or any other dental symptoms, it is important to tell both your treating doctor and your dentist immediately. Your treating doctor may refer you to an oral surgeon with experience in osteonecrosis.

Treatment and management of ONJ

To diagnose osteonecrosis of the jaw, doctors may use x-rays or other radiology. Treatments for osteonecrosis of the jaw may include antibiotics, pain relief medication or oral rinses. Minor dental work may be necessary to remove injured tissue and reduce sharp edges of the bone. Surgery is typically avoided because it has not been reliably shown to help. Regular dental check ups are also recommended.

If a person with myeloma is on bisphosphonate therapy and develops ONJ then the treating doctor will assess each individual case of ONJ and decide whether the bisphosphonate therapy needs to be stopped and for how long. The type and frequency of bisphosphonate therapy may also be changed. For instance in cases where there is a risk of the person with myeloma developing bone problems if not on bisphosphonate therapy then the doctor may decide on an interval of three months between bisphosphonate therapy or change the IV drug over to an oral drug.

Prevention of ONJ

The following points are important in preventing or reducing the risk of ONJ occurring:

  • If possible, you should have a routine dental examination and X-ray and any necessary invasive dental work carried out, before starting on treatment with bisphosphonates
  • Once on bisphosphonates, you should maintain good mouth hygiene and have regular dental check-ups
  • Invasive dental procedures (that is removal of a tooth or surgery) should be avoided if possible when on bisphosphonates. If invasive treatment is absolutely necessary this should be done in collaboration with an experienced oral and maxillofacial surgeon. Some doctors may recommend you stop bisphosphonate treatment before dental treatment and re-start once healing is complete. Other routine dental treatments such as cleaning and scaling, fillings etc. are usually okay.

Putting ONJ into perspective

The proven effectiveness of bisphosphonates in treating and preventing bone disease has to be balanced against the relatively small risk of ONJ occurring. Your doctor should discuss this with you.

Self care tips

Below are some things you can do to help reduce the risk of ONJ occurring:

  • Maintain good mouth care—brush your teeth regularly and use any mouthwashes prescribed
  • Make sure dentures fit properly and don’t rub
  • Visit your dentist regularly for check-ups
  • Make sure your dentist knows you are on a bisphosphonate treatment
  • Tell your doctor/nurse about any dental work you may need
  • Look out for any symptoms in your mouth such as pain, numbness or sore areas
  • If you are on IV or oral bisphopshonates you should report any such symptoms to your doctor/nurse

References
Adapted from the Myeloma UK Fact sheet—Osteonecrosis of the Jaw (ONJ)

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