Wed Apr 13, 2005 12:50 AM ET

GAITHERSBURG, Md. (Reuters) - Mentor Corp. will try to sway a U.S. advisory panel in favor of silicone breast implants on Wednesday, a day after they narrowly rejected a rival's bid to end a 13-year ban on the devices.

The advisory panel to the U.S. Food and Drug Administration ruled 5-4 on Tuesday that Inamed Corp. did not provide compelling evidence that its silicone gel implants were safe.

The FDA banned silicone breast implants for most women in 1992 amid concerns that leaking silicone could cause disabling diseases. The agency will consider the panel's input when deciding whether to lift the sales restrictions.

Studies have failed to find a connection between silicone implants and rheumatoid arthritis, lupus and other chronic diseases that many women tie to the devices.

The implants can cause pain and other local complications, and they can break and require new operations to replace them.

Many women and plastic surgeons say silicone implants look and feel more natural than saline breast implants, the only option for most women in the United States.

Implant makers also say today's silicone implants are more durable than older versions, and the gel is stickier and less likely to migrate.

But a majority of the advisory panel said they wanted more information from Inamed about implant ruptures.

"We don't really know why this device is failing and when it fails," said Stephen Li, a panel member and president of Medical Device Testing and Innovations.

While the FDA and the advisory panel are supposed to review each company's application on its own merits, industry analysts said the vote on Inamed was a likely signal of what Mentor would face.

"It's hard not to believe that the decision today will have an impact" on Mentor's application, said Ira Loss, who follows the FDA for Washington Analysis Corp.

In the United States, only breast cancer survivors and others needing reconstruction or implant replacements can now receive silicone implants, through clinical trials.

Inamed, which is being bought by Medicis Pharmaceutical Corp., said it will keep collecting data on its breast implants. The FDA rejected an earlier application from the company for silicone implants in January 2004.