There have been three generations of silicone-gel breast implants. First generation implants (thick wall – thick gel with Dacron patches) were made from 1963 to 1972. Second generation implants (thin wall-thin gel) were made from 1972 until the mid 1980s. The introduction of third generation implants (stronger wall, low-bleed) was geographically dependent. In Canada, Dow Corning Silastic II implants were introduced in 1986, and Surgitek SCL implants were introduced in 1988. In the present study, a total of 352 silicone-gel breast implants were removed from 239 patients between 1981 and 1995. Their failure properties were dependent upon their generation (year of manufacture) and, for second generation implants, their duration in situ. Of the 352 implants, 20 were first generation, and all were fully intact. Twenty-eight were third generation implants, and 27 were fully intact. Failure properties of the 302 second generation implants were dependent upon their duration of implantation. A survival curve indicated that these implants began to fail (by leaking or rupturing) after four years in situ. By six years, 40% had failed. After 12 years, 95% had failed. Of the 171 second generation implants removed between 1991 and 1995, 77% had failed. The failure properties were similar for the three main manufacturers: Dow Corning, Heyer-Schulte and Surgitek. The failure rate for second generation implants is much higher than was previously believed. This is particularly significant in view of the current difficulty in diagnosing implant failure.
In-Situ Environmental TEM Study of Solid-Gas Interfacial Process in Energy Materials
