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.

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