The Food and Drug Administration has overruled an advisory committee by granting conditional approval to Inamed ( IMDC) to sell silicone gel breast implants for cosmetic surgery.

If the agency ultimately approves the Inamed product, the Santa Barbara, Calif.-based company will join Mentor ( MNT), its next-door neighbor and rival, in selling these implants.

Mentor received conditional FDA approval in late July, but neither the company nor the FDA described the conditions or the timetable for meeting the conditions.

U.S. sales of silicone gel implants have been restricted since 1992 to a few uses, such as for women undergoing breast reconstruction after mastectomies and women whose silicone gel implants had ruptured. The restrictions reflect tougher FDA requirements that manufacturers provide long-term safety data to support applications for their devices.

The FDA's announcement on Wednesday sent Inamed's stock rising $5.96, or 8.4%, to $77.02, a new 52-week high. In the first two hours of trading, more than 3.44 million shares were traded, or nine times the average daily trade for the last three months. Mentor's stock fell $2.38, or 4.5%, to $50.18 in heavy trading.

The FDA offered no details about the conditions or timetable for approving Inamed's implant. "The conditions outlined in this letter are generally in line with our expectations and the discussions that took place at previous FDA advisory panel meetings, and we look forward to working with the agency ... in addressing them," said Nick Teti, Inamed's chief executive officer.

The FDA noted that an advisory committee voted 5-4 in April against Inamed's silicone gel implant application. "Since then, Inamed has providedFDA with additional information to address the primary safety concerns discussed by the panel," the agency said Wednesday. The FDA said Inamed will no longer make a certain implant that had raised safety concerns among panel members.

This is the same panel of medical experts that recommended approval of Mentor's silicone gel implant by a 7-2 vote.

The panel suggested a number of conditions, such as restricting the sale of implants to board-certified plastic surgeons who complete special training and to patients who sign documents showing they understand that the implants could rupture. The panel also said Mentor should prepare a patient registry to examine the implants' long-term health effects and to conduct a clinical study that would assess the implant's rupture rate over 10 years.

After the advisory committee backed Mentor's product and opposed Inamed's implant, angry Inamed executives began discussing their application with the FDA, asking the agency to override the panel's recommendation.

Analysts say cosmetic surgery will represent the lion's share of silicone gel implant sales in the U.S. Both companies sell silicone gel implants in foreign markets, and both sell saline, or salt water-filled, implants for cosmetic and other uses in the U.S. The implant companies and plastic surgeons say women prefer the silicone gel implants because they have a more natural look and feel than the saline implants.