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Osteonecrosis of
the jaw (ONJ) is a condition in which part of the jaw bone is no longer
alive and cannot regenerate itself due to a lack of blood supply.
Most
commonly in the past, patients developed ONJ after bone trauma, such as a tooth
extraction.
Rather than healing, the bone begins to die. In some cases, the
bone becomes exposed, which can lead to serious infection and fracture.
In
extreme cases, surgery is required to remove the dead bone.
The most common
signs and symptoms of ONJ include pain, soft-tissue and jaw swelling,
loosening of teeth, drainage, exposed bone, and infection.
Numbness,
heaviness and other
sensations in the jaw may also occur in some
individuals.
In order to diagnose ONJ, doctors may perform panoramic and
tomographic imaging. They may also take microbial cultures and tissue biopsies
in order to rule out other kinds of infections. Early detection of ONJ is
imperative to preserving the jawbone.
Between 2001 and
2003,
two oral surgeons, Salvatore Ruggiero and Robert Marx, specialists in
problems of the jaw, began researching ONJ after seeing an unusual increase in
the number of patients with deteriorating jawbones.
After carefully studying
the medical records and histories of their patients, the two surgeons discovered
that only one common thread existed-- the patients had been treated with Aredia
or Zometa.
Aredia and Zometa
are intravenous bisphosphonates. Bisphosphonates are a class of
bone-strengthening drugs used to prevent bone loss associated with multiple
myeloma, bone metastases in patients with advanced cancers, and osteoporosis.
Most of the patients seen by Dr. Ruggiero and Dr. Marx were cancer
victims.
Bisphosphonates
prevent metastatic cancer cells from dissolving bone. However, new cells will
not grow unless older old ones are killed off.
Bisphosphonates bond to bone
surfaces and prevent osteoclasts (cells that breakdown bone) from doing their
job. Because jawbones have rapid cell turnover, bisphosphonates can affect their
ability to regrow.
The result is that the jawbone does not heal properly
after any significant trauma, i.e., dental work, and patients become prone to
infections and ONJ.
By September 2003,
both Dr. Ruggiero and Dr. Marx had published articles regarding the link between
ONJ and bisphosphonates. In September 2004, Novartis and the FDA revised the
labels of Aredia and Zometa to include a precautionary statement about the
potential risk of developing ONJ. Novartis also sent letters to physicians
warning them of this potential side effect.
For
additional information about ONJ, click
here
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