On Tuesday, experts rejected Inamed's application in part because the company relied on projections and did not directly study its implants' reliability for longer than three years.
Mentor also did not directly study long-term use, but instead offered laboratory stress testing that the company said was proof that the implants could withstand up to 60 years of wear and tear in the body.
"These are two different devices," said panelist Stephen Li, who supported Mentor's application after opposing Inamed's bid the day before. "They [Mentor] had an extremely low rupture rate."
Still, several panelists said they were uneasy with how the patients and physicians would use the implants because of the extreme difficulty in detecting ruptures in the two companies' studies. More than 85% of ruptures in Inamed's study occurred with no symptoms, while all of the ruptures in Mentor's trial had no outward signs and required imaging of the breast (an MRI scan) to detect them.
That fact led several experts to worry that thousands of women could go for years with broken implants in their bodies while there are still some questions about the health effects of leaked silicone.
Thousands of women have blamed ruptured implants for diseases including autoimmune disorders and cancer, though a 1999 Institute of Medicine study found no hard link between the products and systemic disease. Still, that same year, former implant maker Dow Corning agreed to pay $3.2 billion to settle health claims in a major class-action lawsuit.
The problem of "silent" implant rupture led experts to predicate their approval on a recommendation that women undergo an MRI scan five years after receiving their implants and that the devices be removed if breaks are found.
The panel also recommended that all patients be required to receive education and sign an informed consent form before surgery. The panel also recommended that only physicians who undergo a certification course be allowed to use them in surgery.
"The access needs to be limited. Don't just assume physicians have had this training," said Michael J. Miller, MD, a panel member and plastic surgeon from the University of Texas.