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P ER S PE C T IV E

Osteonecrosis of the Jaw — Do Bisphosphonates Pose a Risk?

Osteonecrosis of the Jaw — Do Bisphosphonates Pose a Risk?
John P. Bilezikian, M.D.

N

itrogen-containing bisphosphonates are used widely for the management of metastatic cancer in bone (intravenous zoledronic acid or pamidronate), for the prevention and treatment of osteoporosis (oral alendronate,risedronate, and ibandronate and intravenous ibandronate), for the treatment of Paget’s disease of bone (intravenous pamidronate and oral alendronate and risedronate), and for the short-term management of acute hypercalcemia (intravenous zoledronic acid and pamidronate). The nitrogen moiety attached to the side chain of the middle carbon of the phosphorus–carbon–phosphorus bisphosphonate backbone rendersthese drugs much more potent as inhibitors of bone resorption than the bisphosphonates that do not contain nitrogen (etidronate and clodronate). Bisphosphonates reduce the survival and function of osteoclasts, the bone-resorbing cells. These antiresorptive actions largely account for the drugs’ efA R1 O OH P OH R2 C O P OH OH

ficacy in conditions in which the rate of bone resorption exceeds therate of bone formation. Until recently, the only adverse events of substantial consequence

Predisposing factors appear to be dental disease, dental surgery, oral trauma, periodontitis, and poor dental hygiene.
associated with the nitrogen-containing bisphosphonates were upper gastrointestinal intolerance (with oral administration) and a short-lived acute-phase reaction characterized by fever,myalgias, and an influenza-like syndrome (with intravenous administration).
B NH2 CH2 CH2 O OH P OH CH2 C OH O P OH ONa · 3H2O

Structures of a Generic Bisphosphonate (Panel A) and a Nitrogen-Containing Bisphosphonate (Panel B).

Now another potential complication of these agents — osteonecrosis of the jaw — has surfaced. Osteonecrosis of the jaw is characterized clinically by an area ofexposed bone in the mandible, maxilla, or palate that typically heals poorly or does not heal over a period of 6 to 8 weeks. The diagnosis is primarily a clinical one, but imaging studies such as computed tomography can be helpful (see images). This condition in connection with bisphosphonate use was first reported in 2003, or 5 to 10 years after these drugs were approved in the United States fortheir current indications; it was rarely seen before then. Most of the reported cases (95%) have been associated with zoledronic acid or pamidronate given intravenously to control metastatic bone disease.1,2 When these drugs have been administered intravenously in patients with cancer, the reported incidence of osteonecrosis of the jaw has ranged from 1.3% in a preliminary retrospective survey3 to 4to 7% in another report.1 Myeloma and breast cancer are by far the most common cancers associated with intravenous bisphosphonate use and osteonecrosis of the jaw.1 Predisposing factors for the development of osteonecrosis of the jaw appear to be dental disease, dental surgery (e.g., tooth extraction), oral trauma, periodontitis, and poor dental hygiene. Treatment with chemotherapy or

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nengl j med 355;22

www.nejm.org

november 30, 2006

Downloaded from www.nejm.org by TONI HOMBERG on August 26, 2008 . Copyright © 2006 Massachusetts Medical Society. All rights reserved.

PE R S PE C TI V E

Osteonecrosis of the Jaw — Do Bisphosphonates Pose a Risk?

A

B

Computed Tomographic Scans Showing Osteonecrosis of the Right Maxilla (Panel A, arrow) and ResultantOpacification of the Sinus (Panel B, arrow).

corticosteroids is also common among affected patients. The lesion is painful in many, but not all, patients, and infection is often present. Approximately two thirds of cases involve the mandible and the rest involve the maxilla. In one unusual case, osteonecrosis of the external auditory canal developed in a patient with myeloma who had received...
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