(NaturalNews) Widely used osteoporosis drugs can significantly increase the risk of bone death in the jaw, according to a study conducted by researchers from the University of Southern California (USC) School of Dentistry and published in the Journal of the American Dental Association.

Researchers found an increased prevalence of osteonecrosis of the jaw (ONJ) among the 208 patients in the School of Dentistry's medical records database who were taking the osteoporosis drug alendronate (marketed as Fosamax).

ONJ occurs when reduced blood flow to the bones in the jaw leads to the death of bone tissue, producing symptoms including infection, loose teeth, exposed bone, soft-tissue swelling and pain. Up until the publication of the current results, researchers had believed that the ONJ risk from oral osteoporosis drugs was "negligible."

Fosamax is the 21st most common drug prescribed in the United States, and the most widely prescribed oral drug in the bisphosphonate family.

Bisphosphonates protect against fractures and the loss of bone mass in osteoporosis patients by interfering with the process by which the body removes calcium and other minerals from bones. Well-known side effects of the drugs include an elevated risk of thigh-bone fractures, inflammatory eye disease and irregular heartbeat. Prior research has shown that patients taking high intravenous doses of bisphosphonates also have an elevated risk of ONJ.

According to the current study, however, ONJ risk is increased even in those who take lower doses of oral bisphosphonates for as little as one year. The researchers found that ONJ tends to occur after a routine tooth extraction, perhaps because bisphosphonates have lowered the bones' resistance to bacterial infection.

Researcher and dentist Parish Sedghizadeh was inspired to conduct the study when he noticed unusually high ONJ rates among patients at his dental clinic in recent years -- as many as four per week. The USC School of Dentistry has now adopted a policy of screening patients for bisphosphonate use before performing dental procedures.

Sources for this story include: www.washingtonpost.com.