Breast implants have evolved rapidly over the past 30 years, from a weak shell with liquid silicone to highly cohesive silicone gel implants. More cohesive breast implant units help limit the risk of any silicone leakage and spread. Fourth generation breast implants have been found to be safe, with long-term studies demonstrating safety and durability. Cohesive silicone gel implants have helped cap the small quantities of low molecular weight (LMW) silicone compounds, as well as platinum (in zero oxidation state), which have been found to diffuse (bleed) through an intact implant shell.
The evidence is mixed as to whether there are any clinical consequences associated with gel bleed. Studies on implants implanted for a long duration have suggested that such bleed may be a contributing factor in the development of capsular contracture and lymphadenopathy. However, evidence against gel bleed being a significant contributing factor to capsular contracture and other local complications, is provided by the fact that there are similar or lower complication rates for silicone gel-filled breast implants than for saline-filled breast implants.
Saline-filled breast implants do not contain silicone gel and, therefore, gel bleed is not an issue for those products. Furthermore, toxicology testing has indicated that the silicone material used in the Mentor implants does not cause toxic reactions when large amounts are administered to test animals.
It also should be noted that studies reported in the literature have demonstrated that the low concentration of platinum contained in breast implants is in the zero oxidation (most biocompatible) state. In addition, two separate studies sponsored by Mentor have demonstrated that the low concentration of platinum contained in its breast implants is in the zero oxidation (most biocompatible) state.
Mentor performed a laboratory test to analyze the silicones and platinum—used in the manufacturing process—that may bleed out of intact implants into the body. Over 99 percent of the LMW silicones and platinum stayed in the implant. The overall body of available evidence supports that the extremely low level of gel bleed is of no clinical consequence.
source: Mentorcorp