Laird Harrison

March 22, 2011

March 22, 2011 (San Diego, California) — Oral bisphosphonates do not increase the risk for osteonecrosis of the jaw, according to researchers who presented a study combining retrospective and prospective data here at the International Association of Dental Research 89th General Session and Exhibition.

"We looked at millions of patients in databases and hundreds in controlled trials and did not find any increased risk," Marjorie K. Jeffcoat, DMD, from the University of Pennsylvania in Philadelphia, told Medscape Medical News.

The study did find a 6-fold increased risk for osteonecrosis of the jaw in patients taking intravenous (IV) bisphosphonates.

Many other studies have found strong evidence of a link between IV bisphosphonates and osteonecrosis. The effects of the oral version of the drug have been more controversial, but the American Association of Oral and Maxillofacial Surgeons recommends that some patients consider stopping oral bisphosphonates before oral surgery.

To gather prospective data, Dr. Jeffcoat and colleagues conducted 3 randomized double-blind placebo-controlled clinical trials with a total of 516 patients. The patients took oral bisphosphonates (alendronate or risedronate) for 2 years. Of these patients, 386 had periodontitis and 130 needed dental implants. Patients underwent examinations every 3 months, which included taking a history to look for signs of osteonecrosis of the jaw.

None of these patients developed osteonecrosis of the jaw, regardless of whether they were receiving oral bisphosphonates or placebo.

To gather retrospective data, the researchers examined a database of more than 55 million people covered by 70 American health plans from 2000 to 2006. They divided patients according to bisphosphonate use: IV, oral, or none. All these patients were followed for at least 6 months, and pre- and postindex diagnoses were required.

From this cohort, the researchers identified 423,845 patients who had never received bisphosphonates, 213,364 who received oral bisphosphonates, and 2321 who received IV bisphosphonates.

They calculated an adjusted odds ratio of 1.03 (95% confidence interval [CI], 0.86 to 1.23) for the patients receiving oral bisphosphonates and 6.02 (95% CI, 3.77 to 9.53) for the patients receiving IV bisphosphonates.

On the basis of these results, Dr. Jeffcoat said that patients with osteoporosis and their dentists should not worry about the effects of oral bisphosphonates on dentistry, and added that drugs are an important treatment for osteoporosis. "As a person sitting here with a broken hip, I would take bisphosphonates," said Dr. Jeffcoat, who needed a cane to support her as she walked around the conference. She said the risk for death from an osteoporotic broken hip is about 20%.

Generally, patients taking IV bisphosphonates are using these drugs because they have cancer, and dentists should take their cues from the physicians treating the cancer, she said. "Dentists always have to worry about patients with cancer and what drugs they are on."

However, other bisphosphonate researchers at this meeting said they could not draw such definitive conclusions from the data. "The study findings are interesting, if they can be validated. We've known for some time now that the risk of [osteonecrosis of the jaw] from oral [bisphosphonates] is low, compared with intravenous use, but [saying] that there is no risk, in my opinion, goes against all the current available literature base on this topic," Parish P. Sedghizadeh, DDS, MS, told Medscape Medical News.

He cited a recent case–control study of practice-based networks (J Dent Res. Published online February 11, 2011) that found a higher incidence of osteonecrosis in patients receiving oral bisphosphonates.

One reason the University of Pennsylvania study might not have found osteonecrosis is that the prospective part of the study only tracked patients for 2 years, Dr. Sedghizadeh said. In his experience, osteonecrosis is associated with oral bisphosphonate use of more than 3 years.

"Before [bisphosphonate] drugs were on the market, reports or cases of osteomyelitis or osteonecrosis of the jaw were rare," he said. "Once we started seeing more of these cases clinically, we knew something was going on, and then the link to [bisphosphonate] use was made."

Gayathri Subramanian, BDS, a researcher from the University of Medicine and Dentistry of New Jersey in Newark, told Medscape Medical News that he wondered about the dose of bisphosphonates used in the study, the duration of bisphosphonate use, and whether patients had undergone invasive dental procedures. All these factors could affect the findings, he said.

He estimates that the incidence of bisphosphonate-related osteonecrosis in patients receiving oral bisphosphonates is about 0.04%. "The retrospective study does have statistical power to detect [bisphosphonate-related osteonecrosis], although the above factors need to be taken into consideration," he said.

Dr. Jeffcoat, Dr. Sedghizadeh, and Dr. Subramanian have disclosed no relevant financial relationships.

International Association of Dental Research (IADR) 89th General Session and Exhibition: Abstract 890. Presented March 17, 2011.

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