 Silicone gel-filled breast implants were introduced in the early sixties and were in wide-scale distribution by the time the Medical Device Amendments to the Food Drug and Cosmetic Act was passed in 1976. In 1983, gel-filled breast implants were designated as Class III devices requiring premarket approval. In May 1990, the Food and Drug Administration FDA published a proposed request 515b for Premarket Approval Applications PMA and in April 1991 published the final request. This final publication put manufacturers of gel-filled breast implants on notice that for continued marketing of gel-filled breast implants, a PMA was due to FDA in 90 days from the final publication date. 