The company was trying to market a newer implant filled with thicker silicone that officials said was less liquid than in previous models and therefore less likely to leak.
But a majority of experts said it was troubled that the company had no information on the implants' durability beyond four years, raising questions about how many could break after extended use.
Company officials had estimated that 14% of the implants would rupture within 10 years of surgery. FDA scientists had attacked that assertion, saying that it was based on an assumption that the devices would fail at a constant rate each year.
"It is difficult to predict the probability of rupture by year 10 with available data," Pablo Bonangelino, PhD, an FDA statistician told the panel.
"I feel a pressing urgency on us to approve this device at this time and I don't know why. I don't feel secure about the safety," said Amy E. Newburger, MD, a panel member and dermatologist from Scarsdale, N.Y.
Other experts -- primarily the panel's several plastic surgeons -- said they were confident that relatively few of the implants would fail after three years.
Inamed officials had promised to continue an ongoing study of silicone implants, and to launch a program educating surgeons on the proper handling and follow-up for the products.
Company data also showed that women experienced no symptoms in 86% of cases of rupture, leading several experts to question how physicians would be able to screen patients for leaking implants.
The company's application was strongly backed by plastic surgeons, who performed more than 300,000 breast implant procedures in 2004. "They feel more like breast tissue in their consistency. They ripple less and therefore feel more natural. Patients deserve to have a choice," one surgeon told the panel.
The application was equally opposed by dozens of women's groups and individual patients, who said that companies including Inamed have never shown t that silicone was safe to reside in the body for years.
Venessa Rose Presuto told panelists that she developed heart problems, skin sores, and hair loss after receiving silicone implants as part of an Inamed clinical trial several years ago. Leaking silicone led doctors to remove her breast tissue, she said.