Ultimate Strength Properties of Control and Explanted Silastic 0 and Silastic I Silicone Gel-filled Breast Implant Shells

Background: The effect of in vivo implantation on breast implants is important to both physicians and patients, but little information about the in vivo aging process of silicone gel-filled breast implants has appeared in the literature. The effects of the in vivo aging process could affect the durability of breast implants. Objective: The purpose of this study was to investigate changes in the mechanical and chemical properties of breast implant shells as a function of implantation time. Methods: The ultimate mechanical properties of the shells from single-lumen silicone gelfilled Silastic 0 and Silastic I explants with in vivo duration times ranging from 6 to 28 years were measured and compared with the corresponding properties of unimplanted control single-lumen silicone gel-filled implants. Ultimate tensile strength, elongation-tofailure, and tear resistance were measured for both explant and control shells through use of identical testing protocols. In addition, the tensile strength and elongation-to-failure of shells extracted with hexane to remove non–cross-linked silicones were measured for both explants and control implants. The ultimate strength data were plotted as a function of implantation time, along with data from other research institutions. Results: Statistical analysis of the data indicated that the ultimate mechanical properties of tensile strength, elongation-to-failure, and tear resistance are not functions of implantation time for up to 28 years of implantation. Conclusions: The results of this study show that there is no significant degradation of the mechanical properties of the elastomeric shell as a function of time.