Osteonecrosis of the Jaw (ONJ)


Osteonecrosis of the jaw (ONJ), also known as "dead jaw syndrome," Avascular Necrosis and Aseptic Necrosis, is a rare but serious condition involving severe loss or destruction of the jawbone. ONJ disrupts the blood supply to the jawbone. This causes tiny breaks that can lead to total bone collapse and significant damage, including tooth loss.

Symptoms of ONJ

Symptoms of ONJ include:

  • Pain, swelling or infection of the gums or jaw
  • Gums that do not heal
  • Loose teeth
  • Numbness or heaviness in the jaw
  • Drainage of jaw abscesses (pus)
  • Exposed bone showing through missing gum tissue

If you have ONJ, you may not show symptoms for weeks or months. ONJ may only become evident when the bone is exposed in the jaw.

Causes of and Risk Factors for ONJ

The causes of ONJ are still poorly understood. ONJ sometimes appears to develop when the jaw does not heal after minor trauma, such as a tooth extraction in which bone is left exposed. However, there are several risk factors that may increase your likelihood of developing ONJ. These include:

  • Radiation therapy (head or neck)
  • Chemotherapy
  • Treatment with steroids, such as cortisone
  • Anemia (low blood count) and other blood-related disorders
  • Infection
  • Poor oral health and nutrition
  • Gum disease or dental surgery, such as tooth extractions
  • Alcohol abuse and cigarette smoking
  • Poor blood circulation or clotting problems
  • Cancer (multiple myeloma or metastatic disease to bone)
  • Osteoporosis (a thinning of the bones), Paget's disease (a chronic condition characterized by abnormal, enlarged and brittle bone that is more prone to breakage) or other indications for bisphosphonate treatment

Causes of ONJ: The Bisphosphonate Connection

A growing body of evidence is raising concerns about the alarming correlation between the increasing popularity and use of bisphosphonates – a class of drugs that inhibit osteoclasts (cells that break down bone) and disturb the differentiation of osteoblasts (bone forming cells) – and the greater incidence of reported ONJ cases. Currently, scientific information does not understand all the links between bisphosphonates usage and ONJ. However, researchers speculate that while bisphosphonates support the buildup of bone in areas weakened by disease, some individuals may experience ONJ if bone should become exposed as a result of oral surgical procedures.

Intravenous (administered by veins) bisphosphonates are primarily used to reduce bone pain and hypercalcemia (abnormally high calcium levels in the blood) associated with metastatic breast cancer, prostate cancer and multiple myeloma. Cancer patients generally take one of two bisphosphonates intravenously: Zometa (zolendronic acid) or Aredia (pamidronate). These drugs prevent bone pain and fragile bones.

Oral (swallowed) bisphosphonates are used to prevent bone loss and are prescribed for people with osteoporosis, osteopenia (a precursor to osteoporosis) or Paget's disease. Osteoporosis and osteopenia patients usually take bisphosphonates as pills, in much lower doses than cancer patients. Those drugs – Fosamax (alendronate), Actonel (risedronate) and Boniva (ibandronate) – reduce the risk of fractures of the spine or hip.

Most cases of ONJ have involved people who received intravenous bisphosphonates to treat cancer that had spread (metastasized) to the bone. More rarely, ONJ has occurred in people taking oral bisphosphonates.

Most cases of bisphosphonate-related osteonecrosis of the jaw (BRONJ) have been diagnosed after dental procedures such as tooth extraction. However some reports indicate the spontaneous development of BRONJ without a prior traumatic dental procedure.

Time Considerations for ONJ

Bisphosphonates can persist in bone for months, even years, after the drug is used. According to some experts, adverse effects from oral bisphosphonates will not show up until three years after treatment starts, and after that time, the chance of developing ONJ remains very low. The incidence of developing complications while taking intravenous bisphosphonates is higher.

Dental implants have been known to fail in people taking oral bisphosphonates. However, studies of patients taking oral bisphosphonates and receiving dental implants indicate a very low risk of either implant loss or BRONJ following implant placement, especially if the person has been taking the bisphosphonate for less than three years.

Diagnosis of ONJ

To diagnose ONJ, doctors use X-rays or test for infection by taking microbial cultures. In addition, there is a new screening tool available that helps people who have been taking an oral bisphosphonate for more than three years to determine their risk of developing ONJ. This laboratory test, called the CTX (C-Telopeptide), measures the rate of bone turnover. Results of 150 to 600 pg/mL (picogram/milliliter) indicate minimal-to-no risk of developing ONJ; results of less than 100 pg/mL indicate a high risk. The CTX test can be ordered by a dentist or physician and is performed by an outside laboratory, such as Quest Diagnostics or others.

Treatment Options for ONJ

Unfortunately, ONJ is irreversible, meaning there is no cure at this time. Currently, treatments to control the condition and alleviate and/or stop certain ONJ symptoms include antibiotics, chlorhexidine mouth rinses and removable mouth appliances. Minor dental work may be necessary to remove injured tissue and reduce sharp edges of damaged bone. However, surgery is usually avoided because it may worsen the condition.

Stopping the use of bisphosphonates is not considered effective, since no one knows precisely how long the ONJ risk remains. However, some physicians and dentists still suggest stopping the drugs for a few months before and after an invasive dental procedure; others recommend six months to a year.

Prevention Methods

Practicing good oral hygiene and getting regular dental care may be the best ways to lower your risk of ONJ. Inform your dental professional if you are taking oral bisphosphonates, get routine dental cleanings and choose root canal therapy over extractions.

Have any necessary dental work completed before taking bisphosphonates. This is especially important if you are planning on undergoing gum surgery, receiving implants or having tooth extractions.

Experts also recommend that people consume 1,000 to 1,200 milligrams of calcium a day, add vitamin D to their diet, exercise and weight train, quit smoking, and reduce caffeine and alcohol intake.

Recommendations for Cancer Patients with ONJ

Recommendations for the prevention, diagnosis and treatment of ONJ in cancer patients on intravenous bisphosphonates include the following:

  • Schedule a dental exam and cleaning before cancer treatment begins and periodically while undergoing treatment.
  • Update your medical history with your dentist to include the cancer diagnosis and treatments.
  • Have your dentist check and adjust dentures as needed to avoid soft-tissue injury.
  • Provide your dentist and oncologist with each other's contact information for consultation.
  • Tell your dentist and physician about any gum bleeding, mouth pain or infections, or unusual feeling in the teeth or gums.
  • Maintain excellent oral hygiene to reduce your chances of infection. If dental infections do occur, get them managed promptly and non-surgically when possible.

When dental work – especially tooth extraction – is required after starting bisphosphonate therapy, patients, physicians and general dentists should consult with appropriate dental specialists, including periodontists, who focus on the treatment of the tissues surrounding and supporting the teeth, such as the gingiva (gums), bone and periodontal ligament, and oral and maxillofacial surgeons, who specialize in the diagnosis and surgical and adjunctive treatment of diseases, injuries and defects affecting the functional and esthetic aspects of the face, mouth, teeth and jaws.

For people who develop ONJ while on bisphosphonate therapy, dental surgery may worsen the condition. Clinical judgment by the treating physician(s) and dentist(s) should guide the management plan of each patient based on individual benefit/risks.

Points to Consider

As with any medication, if you are taking oral and/or intravenous bisphosphonates, consult with everyone on your medical and dental treatment team to fully understand the potential risks and benefits.

For instance, if you take an oral bisphosphonate for osteoporosis, don't stop taking the medication without first consulting your medical and dental team. The risk of developing ONJ due to bisphosphonate use is very low in people without cancer or dental problems. Currently, there are fewer than 200 reported cases of ONJ among the more than 20 million patients taking oral bisphosphonates, according to manufacturer data.

Keep in mind, though, that reports of the link between bisphosphonate drugs and ONJ only started being reported in 2003. Currently there is no long-term clinical trial data evaluating the dental management of patients on bisphosphonate therapy. The current recommendations for prevention and treatment of ONJ are based on expert opinion and likely will be updated and improved as new information becomes available.

For now, everyone – you, your dentist, treating physicians and dental specialists – needs to work in collaboration to ensure the latest, most accurate, safest and most effective treatment plan for your individual medical and dental needs.


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