Fosamax. Actonel. Boniva. These drugs have been advertised on TV so much they’ve become household words.

Collectively, they’re known as bisphosphonates, and they can work wonders for people who have osteoporosis, often stopping or even reversing the loss of bone density.

But there’s growing concern about a potential side effect of these medications. Osteonecrosis of the jaw (ONJ) is a serious condition in which the cells of the jawbone die, causing infection, loss of teeth, a gaping wound on the inside of the mouth, and sometimes sudden fracture of the jaw.

"It can get very bad," said Dr. Fred Simonton, an oral-maxillofacial surgeon in Gainesville. "If the bone is dead, you have to remove it or it creates an environment for more infection."

The disease can cause disfigurement and interfere with speaking and eating. Sometimes patients have to undergo multiple reconstructive surgeries to correct the problem.

"The risk (of this drug side effect) may be small, but the consequences are devastating," said Dr. Mark Stevens, chairman of the department of oral and maxillofacial surgery at the Medical College of Georgia.

And the risk may be higher than previously thought.

Originally, ONJ was believed to occur in less than 1 percent of patients taking oral bisphosphonates. The complication was seen mainly in cancer patients, who take high doses of the drugs intravenously.

But a study published last week in the Journal of the American Dental Association found that about 4 percent of dental patients taking Fosamax had ONJ.

That still seems like a relatively small number. But if, say, 10 million Americans take
Fosamax, that could mean as many as 400,000 may develop ONJ.

An estimated 55 million prescriptions for bisphosphonates are written in the United States each year. The drugs are routinely prescribed for women who have gone through menopause, when hormonal changes can cause them to lose bone density.

But a woman may live for 30 years beyond menopause. Should she stay on osteoporosis medication the rest of her life?

"Nobody really knows what is the right amount of time to stay on these drugs. We don’t know the long-term effects," said Dr. Brent Frickinger, a Gainesville rheumatologist. "But I think most patients will stay on it indefinitely. If they go off it, their bone density is likely to decline again."

Frickinger strongly recommends the medication for older patients who have already had a fracture. "The benefits outweigh the risks," he said, noting that many elderly people suffer permanent disability or even death following a hip fracture.

If the patient can’t take bisphosphonates, there are several other treatments for osteoporosis.

"We can try alternatives such as Forteo or Evista, but those medications have their potential risks as well," Frickinger said.

Lifestyle changes such as getting enough weight-bearing exercise and consuming enough calcium and vitamin D are important, he said, but those measures cannot reverse a severe case of osteoporosis.

But when Frickinger prescribes a bisphosphonate, he makes sure the patient understands the risk of ONJ.

"I usually ask the patient if they have any recent or upcoming dental procedures such as tooth extractions, and if so, I might delay starting the bisphosphonate," he said.

That’s the odd aspect of ONJ. The disease almost never starts spontaneously, even if the patient is on an osteoporosis drug. But if she undergoes a dental procedure, that seems to cause changes in the cells of the jawbone.

"You don’t want to disturb the bone," said Dr. Michael Vetter, a Gainesville dentist. "You don’t want to take teeth out, or put in an implant. The standard of care is to try to keep the teeth in the mouth as much as you can."

To treat a condition that might require a simple extraction for an ordinary patient, Vetter may try to perform a root canal if the patient is taking bisphosphonates. So it’s important to know which patients are taking the drugs.

"We now have a sign up front by the reception desk, saying, ‘Please let us know if you’re on these medications,’" said Vetter.

Stevens believes that before patients start taking a bisphosphonate, they should have a dental exam and be screened for periodontal disease. If there’s bacteria lurking in the gums, it may increase the risk of jaw infection.

That’s one reason the necrosis occurs in the jaw instead of in some other bone in the body. Stevens said the jawbone is vulnerable because only a thin layer of tissue separates it from the inside of the mouth.

He said the jaw also has a high rate of cell turnover, and bisphosphonates can interfere with the bone’s ability to heal if it is damaged.

Fosamax was approved by the U.S. Food and Drug Administration in 1995. Ten years later, the FDA asked the manufacturer, Merck & Co., to add an advisory label about the risk of ONJ. Now, some people are wondering whether stronger warnings are needed on Fosamax and other biphosphonates.

Stevens said the incidence of ONJ may have been underestimated because doctors are the ones who usually report adverse side effects of drugs. But when patients have a problem with their teeth, they go to her dentist.

"Physicians weren’t aware of this complication because they weren’t seeing it in their offices. It was showing up in dental offices," said Stevens.

Merck officials have criticized the recent study, saying its methodology was flawed and the number of subjects was too small for the results to be accurate.

Stevens would like to see more research done on the long-term effects of bisphosphonates.

"Most of the patients we see with (ONJ) have been on an osteoporosis drug for at least three years," he said. "Will this become a more significant problem as people are taking these drugs longer? We need to look at whether there is a maximum level where the drug isn’t really doing any good anymore."

Stevens said he’s not advising patients to stop taking bisphosphonates if they need the medication to treat their osteoporosis.

"But it should be an educated choice," he said. "There are questions that are still to be answered."

Simonton said it’s unfortunate that a drug that treats osteoporosis, a painful and disabling condition, may cause another condition that is equally painful and debilitating.

"All medicine is a two-edged sword," he said. "Part of it is going to do what you want, and part of it is going to do something you don’t want. It’s a terrible conundrum."