There are significant differences in weight and volumetric characteristics between silicone and saline breast implants of which most plastic surgeons are unaware. Phase I of this study was a weight measurement focused on recording differences in the weight of saline volumes instilled versus recorded weights of saline implants and expanders. Phase II compared displaced volume differences of tissue expanders with instilled volumes. As a result of this study, surgeons should now be able to precisely calculate the volume created for breast pocket development, allowing for accurate matching of expander and final breast implant.
There are significant differences in weight and volumetric characteristics between silicone and saline breast implant of which most plastic surgeons are unaware.
Plastic surgeons need to be aware of these differences for both in-breast implant exchange from saline to silicone conversions and 2-stage breast reconstruction.
Until now, measuring the volume created by the expander has been solely reliant on using the volume of injected saline into the expander.
The volume occupied by the tissue expander shell and filling port have been largely estimated or disregarded.
In addition, these differences are commonly ignored in saline to silicone gel implant exchanges.
Introduction and background
The aesthetic results and outcomes following breast augmentation and reconstruction with implants and tissue expanders continue to improve and are becoming increasingly accurate. With the advent of 3-dimensional imaging and simulation, very specific volumes of the breast may be calculated, simulated, and compared. Many plastic surgeons continue to be unaware of the differences between saline and silicone devices, and fail to consider the additional weight and displaced volume that the saline shell and expander components add to the weight and volume of the overall device. In addition, saline is more dense than silicone and adds slightly to the volume differences. These differences in volume are becoming more important in achieving optimal outcomes and symmetry. Finally, saline implants are filled in situ, so their weight and displaced volume does not include the implant shell. Silicone implants, however, are constructed, weighed, and volumetrically measured, including the shell weight and total displaced volume, by the manufacturer.
So what weighs more, saline or silicone? Silicone implants will float when placed in a saline bath because silicone is less dense than saline ( Fig. 1 ). Saline implants hover just beneath the surface, because they are isodense with the saline bath ( Fig. 2 ).