Lawyers for Fosamax users who believe their jaws were damaged by the osteoporosis drug on Friday asked a federal judge to order Merck & Co. to provide a dental monitoring program for the drug's users.

The lawyers made the suggestion to U.S. District Judge John F. Keenan as they argued for the case to be certified as a class-action, in order to pursue claims by users who believe the drug caused osteonecrosis of the jaw, a condition in which portions of the jaw bone die, sometimes leaving the bone exposed.

Timothy M. O'Brien, a lawyer for plaintiffs, said hundreds of thousands of patients would benefit from a dental monitoring program that would include regular dental screenings, X-rays and lab tests, all aimed at preventing the need for dental surgery.

Paul Strain, a Merck attorney, called Fosamax a "life altering and life saving drug" that helps to prevent the kind of bone fractures that can hasten the deaths of people as they age. He said the drug was a pioneer 11 years ago.

Strain also said there was no proven link between degeneration of the jaw bone in some patients and Fosamax.

Damage to the jaw bone can result in many ways, including from using steroids, from diseases or weaknesses in the body and from poor dental hygiene.

O'Brien said as many as one in every 296 patients who use Fosamax develop the severe damage to the jaw, though Merck disputed the figure. O'Brien said jaws were more susceptible to damage because they are used so frequently and are under greater stress than most bones.

Keenan did not immediately rule after hearing arguments.

Vance Andrus, another lawyer for the plaintiffs, argued a class-action certification would allow for a trial where a jury could decide whether Fosamax is toxic and hazardous and whether Merck was negligent and should have warned users of dangers.