NEW YORK (CNN/Money) - Breast implant maker Inamed Corp. said Wednesday it received an approvable letter from the Food and Drug Administration, clearing a regulatory hurdle on its path to selling silicone implants in the United States.

California-based Inamed said the letter states certain conditions the company must fulfill for its silicone implants to get approved for the market. An approvable letter is generally seen as a predecessor to product approval by the FDA. Mentor, Inamed's main rival, received an approvable letter from the FDA on July 28.

"We're talking about a near-doubling of the breast implant market," said Jose Haresco, analyst for Merriman, Curhan & Ford Co., reacting to the news. Haresco said that if the FDA approves silicone implants for Inamed and its market rival Mentor Corp., the current U.S. market of about $350 million could expand to nearly $700 million over two to three years.

Inamed's (up $5.87 to $76.93, Research) stock jumped about 8 percent following the news, while Mentor's (down $2.06 to $50.50, Research) stock dropped about 2 percent.

The FDA took silicone implants off the market in 1991 for esthetic use because of health concerns over ruptures and leaks. The U.S. market is currently dominated by saline-filled implants, though silicone remains the implant of choice in Europe and South America. In the U.S., only women seeking reconstructive surgery are permitted to use silicone implants.

Inamed is nearly two months ahead of Mentor in the regulatory process for silicone, but market share in the U.S. is split evenly between the breast implant makers and analysts see them as neck-to-neck in a high stakes race.

"I would be surprised if the market share changed drastically going forward," said Haresco. "They're still very competitive."

Haresco said the letter for Inamed came as no surprise, but he declined to estimate how long it might take the regulatory agency to make a decision regarding silicone. Haresco said that both of the companies received approvable letters for silicone implants in 2002 but were subsequently turned down by the FDA.

The regulatory process has been clouded by controversy, he said, with some critics saying the product "has primarily an esthetic value" and carries health risks.

Inamed and Mentor both sell silicone implants overseas, and are seeking FDA approval for the third and fourth generation implants, which are considered safer than earlier models.

The companies received approvable letters for the third-generation implants, which are made of cohesive gel that the companies say maintains its form and doesn't leak. The companies have also submitted applications for fourth-generation implants, also known as "Gummy Bear" implants because they're made of gel pieces clustered together like rubbery candies.

The companies could also face competition from MediCor Ltd., a Las Vegas-based implant maker that sells silicone overseas. MediCor, founded by implant inventor Donald McGhan, recently acquired two British implant companies and plans to submit applications for saline implants to the FDA.

To read more about MediCor and the grandfather of the breast implant, click here.

Haresco does not own stock in the companies mentioned here.