Ultimate strength properties of explanted and control Silastic II silicone gel-filled breast implant shells

Background: Amid the controversy surrounding the use and durability of silicone gel-filled breast implants, it is important for patients and physicians to understand the factors influencing the long-term durability of these devices. Objective: The purpose of this study was to examine the effects of long-term in vivo implantation on the durability of Silastic II silicone gel-filled breast implants. Methods: The ultimate mechanical properties of shells from Silastic II silicone gel-filled explants with in vivo duration times ranging from 0.3 to 13.2 years were measured and compared with the corresponding properties of unimplanted control implants. The ulti-mate strength data obtained from the present study were combined with data from other institutions to estimate long-term effects. Results: The data show that there is an initial decrease in the shells' ultimate strength properties after implantation but no further significant degradation of the elastomeric shell during long-term in vivo implantation. Moreover, extraction of diluents from the explant shells restores their strength properties nearly to the values measured for unim-planted controls. Conclusions: Implant failure for this type of device is not due to mechanical property degradation during long-term implantation.