Merck, already in a long fight against thousands of Vioxx lawsuits, will soon face a two-front war, as plaintiffs begin to file suit over a different drug: Fosamax.

Merck, the No. 2 U.S. drugmaker, will soon face a federal court suit from a Naples, Florida woman who blames the osteoporosis treatment for the necrosis that rotted her mouth and exposed bone in her jaw. Linda Secrest, 60, who took Fosamax for six years, filed the lawsuit April 10 in Fort Myers, Florida. She accuses Merck of withholding information about the drug's health risks.

Salvatore Ruggiero was puzzled.

Over a three-year period, the jaws of dozens of patients who had undergone oral surgery at his hospital had failed to heal properly. Part of the jawbone had died and become exposed.

"We never saw this before in the jaw" except in patients who had received radiation therapy to that part of the face, says Ruggiero, chief of oral and maxillofacial surgery at Long Island Jewish Medical Center. "It just never existed."