| Second-generation implants also included various "double lumen" designs. These implants were basically a silicone implant inside a saline implant. The binary lumen was an attempt to provide the cosmetic benefits of gel in the inside lumen, while the outside lumen contained saline and its volume could be attuned after placement. The failure rate of these implants is higher than for single lumen implants. The modern versions of these devices ("Becker Implants") are used primarily for breast reconstruction. Third Generation - Silicone Gel-Filled Breast Implants Third-generation implants, developed in the late 1980s and early 1990s, used thicker shells that were coated to decrease gel bleed, and thicker, more cohesive gel filler. These implants are sold under restricted conditions in the U.S. and Canada, and more widely used in other countries. Two companies, Inamed and Mentor, applied for FDA approval for these implants in 1991 and 2003, and were turned down, and have resubmitted applications currently being considered by the FDA. These implants break as they age, and the rate of rupture has not yet been determined. Statistics presented to the FDA is limited to 3 and 4 year data. The enlarged solidity of the gel filler is believed to reduce outflow of the gel compared to earlier devices, but no long-standing studies have been performed to compare leakage rates. According to the FDA study was indicated that most women with these implants will have at least one ruptured implant within 11 years. One study supported by Dow Corning estimates that "at least 15%" of these implants rupture within the first 10 years, which translates to 27.75% of breast augmentation patients. Fourth Generation - Cohesive Gel Implants Evaluation of "gummy bear" or high-cohesive, form-stable implants is in first round stages in the United States. Though these implants are used more widely in other countries, there are no published long-term safety studies. It is considered that the high degree of gel cohesion in these implants is likely to abolish or significantly reduce silicone migration.
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