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We ask the experts to settle common questions we've all wondered about.

QUESTION

A recent study found that certain drugs used to prevent osteoporosis have been linked to dead bone in some people. How great is the risk and should patients be considering other treatment options?

ANSWER

Osteonecrosis of the jaw, a disease in which a patient's jawbone rots and dies, has been associated with the use of bisphosphonates, a popular class of medication for the treatment of osteoporosis.

In most cases, osteonecrosis of the jaw occurs in cancer patients who receive high-dose intravenous bisphosphonates to control high calcium levels or to treat cancer that has spread to the bones. Often, these patients have had chemotherapy or radiation therapy, which increase the likelihood of osteonecrosis.

Poor dental hygiene, invasive dental procedures, use of steroid medications and diabetes are other factors that increase the risk of developing the disease.

Rarely, osteonecrosis of the jaw has been reported in patients with osteoporosis who were taking oral bisphosphonates such as alendronate (brand name Fosamax) or risedronate (Actonel). The dose used in osteoporosis patients tends to be much lower than the amount used in cancer patients.

In a recent study published in the New England Journal of Medicine, the use of the intravenous bisphosphonate zoledronic acid (Aclasta) for women with osteoporosis was no more likely than placebo to be associated with osteonecrosis of the jaw. The risk in both groups was about 1 case per 10,000 patients per year.

Another recent study in The Journal of Rheumatology examined patients who were hospitalized with heart disease, some of whom developed osteonecrosis and others who did not.

Patients with osteonecrosis were more likely to have taken an oral bisphosphonate such as etidronate (Didrocal), alendronate (Fosamax) and risedronate (Actonel) than patients without osteonecrosis. However, this finding may have been related to higher rates of steroid use and cancer in the group with osteonecrosis.

In others words, there may be other issues that put these patients at higher risk. In addition, it is unclear what type of osteonecrosis these patients had; osteonecrosis of the jaw and aseptic osteonecrosis of the hip have very different causes.

Over all, bisphosphonates have been around for many years and are very effective in reducing fracture risk in elderly osteoporotic individuals. There are other classes of medications, such as selective estrogen receptor modulators, that can be used for the treatment of osteoporosis in postmenopausal women.

Most osteoporosis experts feel that the risk of osteonecrosis of the jaw is low among osteoporosis patients on bisphosphonate therapy. If you are taking a bisphosphonate, you should inform your doctor if you are going to have an invasive dental procedure (such as implants or tooth extraction), or if you have a non-healing wound with exposed bone in your mouth.

If you are considering taking a bisphosphonate or another medication to reduce your fracture risk, you should discuss the decision with your doctor and weigh your risk against the pros and cons of these medications.

Dr. Angela M. Cheung is director of the osteoporosis program at the University Health Network and Mount Sinai Hospital in Toronto.