A different method of putting in an artificial implant involves the use of a saline tissue expander to stretch out the chest wall skin and muscle before placing the implant.
First, an empty sack is inserted behind your chest muscle and then the incision is sewn shut. Over time (two to six months), your health care provider will inject increasing amounts of saline into the bag through a valve under the skin. This stretches your skin and muscle.
When your new breast area reaches your desired size, the sack is removed and replaced with a permanent artificial implant (silicone or saline filled). The saline expander is not left in permanently because it does not look as natural as a permanent implant.
An advantage to the expander is that you can get a more natural breast appearance or use a larger permanent implant, since you can stretch your skin out to your desired size. A disadvantage is that some women find the muscle and skin stretching uncomfortable. You will also need to visit your health care provider more frequently to have the saline injected.