In 1961 plastic surgeons Thomas Cronin and Frank Gerow developed the first silicone breast prosthesis with the Dow Corning Corporation. The first woman was implanted in 1962. The implant was made of a silicone rubber envelope (or sac), filled with a thick, viscous silicone gel. When originally introduced in the 1960s, medical devices were not regulated in the United States and consequently no safety data were required. After changing the law in 1976 to give the Food and Drug Administration (FDA) the authority to regulate all medical devices, the FDA "grandfathered" many devices that were already on the market, including breast implants. As a result, these devices could continue to be sold although they had not been through the FDA approval process and long-term safety had never been documented. In 1991, the FDA required that safety studies be submitted by companies that sought to keep their implants on the market in the U.S. The FDA reviewed the data suggested by several implant manufacturers, and determined that the data were not sufficient to prove safety. In 1992, the FDA therefore restricted silicone gel-filled breast implants to clinical tests, mainly for women with implants that need to be replaced or for women demanding reconstruction after mastectomy or breast malformation or. The FDA has not lifted those restrictions, regardless of several following applications for approval. In Canada, silicone gel-filled prostheses were forbidden by Health Canada on January 6, 1992 in response to anxiety raised in the scientific literature regarding possible illnesses associated with the implants. In 1999, Health Canada's Medical Devices Bureau began to make silicone implants available to plastic surgeons again under a Special Access Program. According to the program, surgeons must put forward requests to use silicone implants to the Bureau on a case-by-case basis. First Generation The first generation Cronin-Gerow implants were redesigned in the 1970s with thinner gel and thinner shells. These "second generation" implants had a greater tendency to break and leak, or "bleed" silicone through the porous shell, and complications such as capsular contracture were also rather common. In the 1970s was made one more development - polyurethane foam covering on the shell of implant. According to a Congressional report, 200,000 women received this type of implant before it was discontinued in the early 1990s because of health concerns. Such polyurethane coating was supposed to reduce capsular contracture by means of causing a provocative reaction that disheartened formation of fibrous tissue around the capsule. After FDA scientists resolute that the foam broke down to TDA, a known animal carcinogen, the company extracted the product. Plastic surgeons have found that removing polyurethane-coated implants can be harmful and lead to chronic infection, drainage from the breast and skin ulceration. These implants are not FDA approved for sale in the United States, buy still manufactured in Europe and South America.
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