Is silicone safe to have in the body?

Silicone implants are safe. Period
Breast Implant Illness  and silicone related medical complications are controversial topics. It is a phenomenon which is supported by a wealth of anecdotal data (patient testimony) but no empiric data (hard scientific research). Patient reports a litany of symptoms which they attribute to their implants but the connection is difficult if not impossible to prove via laboratory study.
Physician scientists may recognize anecdotal data but unless it is supported by Class I empiric data, it is difficult to place a great deal of faith in it. Clinicians make decisions based upon evidence based medicine. 
That being said, it is easier to identify what one knows rather than what one doesn't.
What we do know is that by all available measures today...implants are safe and specifically silicone implants are safe.
Silicone breast implants are among the safest medical devices in use today. These devices are also among the most rigorously studied and tested medical devices currently being used in the U.S. today. It is biologically inert  and in that respect no different than the titanium used for bony fixation. There has been no demonstrated link between silicone and the commonly cited myth of autoimmune disease.As always, discuss your concerns with your board certified plastic surgeon (ABPS).

Far more important than the technique is the skill and experience of your plastic surgeon. Choose your surgeon rather than the technique and let them explain why one technique may be better than another.  See the below link on some suggestions on finding the most qualified Plastic Surgeon for a Breast Revision.  Always insist on a board certified plastic surgeon.