One manufacturer couldn't persuade U.S. federal health advisers that it's time to lift a 13-year near-ban on silicone-gel breast implants (search). Now another gets to try.

Advisers to the Food and Drug Administration (search) cited lingering questions about how long the controversial implants really last before breaking and leaking inside women's bodies as they narrowly rejected Inamed Corp.'s bid Tuesday to bring the products back to the U.S. market.

On Wednesday, rival Mentor Corp. (search) gets its chance to persuade the same advisory panel that today's silicone implants are better than versions sold years ago.

But FDA analyses say Mentor has studied the breakage question for an even shorter period than its competitor did, casting doubt on silicone implants' future.

The FDA isn't bound by its advisers' recommendations, but typically follows them.

Without long-term data on implants' safety and durability, "How we can get an informed consent from our patients?" said New York dermatologist Dr. Amy Newburger as she joined fellow FDA advisers in voting 5-4 that Inamed's implants aren't ready for widespread sale.

"It makes me very uneasy," she said. "I don't feel secure about the safety."

Silicone-gel breast implants began selling in 1962, before the FDA required proof that all medical devices are safe and effective. In 1992, complaints that the implants broke and caused illnesses prompted the FDA to ban gel implants except for patients with breast cancer or a few other conditions who enrolled in strict research studies.

Thirteen years later, silicone implants largely have been exonerated of causing serious or chronic illnesses such as cancer or lupus. But they can cause side effects, including infection and painful, rocklike scar tissue. Also, they can break, requiring additional surgery to remove or replace them — and those ruptures can result in silicone oozing into the breast and, sometimes, farther into the body.

Just last year, the FDA rejected requests by Santa Barbara, Calif.-based Inamed and Mentor to lift the near-ban until those durability questions were better answered.

The companies argue that they've done just that, contending that thicker shells and stickier silicone make newer versions of the implants safer than the originals — and just as durable as salt water-filled implants sold without restriction today.

About 14 percent of the silicone implants will break within 10 years, Inamed officials told the FDA panel Tuesday, an estimate derived from a study of 940 patients tracked for three to four years.

But FDA scientists sharply criticized that estimate, saying in contrast that as many as three-quarters of implants may break within a decade, because they'll likely become more fragile as they age, a factor Inamed discounted.

A study by rival Mentor suggests less than 5 percent of its silicone implants broke within three years, but FDA analyses released last week questioned that data's value in settling the issue.