The Food and Drug Administration approved the implants for women 22 and older, or those undergoing breast reconstruction surgery, but warned that patients probably would need at least one additional operation because the implants don't last a lifetime.
The decision clears implants made by two California manufacturers, Inamed Corp. — now part of Allergan Inc. — and Mentor Corp.
"There is reasonable assurance that Allergan and Mentor silicone-gel breast implants are safe and effective, and there is adequate information to enable women to make informed decisions," said Dr. Daniel Schultz, FDA's medical device chief.
Mentor called the decision a "historic moment." Allergan said it created new options for women.
Are silicone implants different now than they were in the early '90s? CBS News medical correspondent Dr. Jon LaPook reports that the manufacturing process is thought to be improved. But due to possible unnoticeable leakage, doctors are recommending periodic MRIs for patients.
However, Dr. Sidney Wolfe, a longtime opponent, called the implants "the most defective medical device FDA has ever approved."
The twin approvals came with conditions, including a requirement that the companies complete 10-year studies on women who have already received the implants to study leaks, as well as begin new decade-long studies of the safety of the devices in 40,000 women.
Shultz called the implants "one of the most extensively studied medical devices. We now have a good understanding of what complications can occur and at what rates."
The FDA warned that the implants are not without risk and that women may not immediately know if their implants break and silicone begins oozing into their breasts. That means women will need regular MRI exams for the rest of their lives to catch those so-called "silent ruptures."
Patients will have to be given special brochures that explain these risks.
The FDA decision opens the implants to much wider use by women seeking to reconstruct or augment their breasts. Since 1992, the silicone implants had been available only as part of research studies.
Silicone-gel breast implants first went on the market in 1962, before the FDA required proof that all medical devices be safe and effective. Thirty years later, they were banned amid concerns about their safety.
At the time, there were worries about a possible connection to a variety of diseases, including cancer and lupus. Alarming cases of ruptures added to the concern.
Since then, most studies have failed to find a link between silicone breast implants and disease.
The rupture issue persists: The implants do not last a lifetime, and eventually they must be removed or replaced, according to the FDA. A 2000 Institute of Medicine report found rupture rates as high as 77 percent.