Breast augmentation -425cc "filled to" 550cc. I'm confused on what it means to "fill" the breasts to a different size?

When you refer to saline implants, the implants come empty and can be overfilled to a larger size. So a 450 saline implant can be overfilled to 500 cc's.  In fact this is commonly done and the manufacturer even says it's okay.  If you are using silicone, 450 cc's is 450 cc's and the size cannot be altered.  Hope this clears things up.

Those patients had saline implants placed.  With a saline implant the surgeon "fills" the implant the day of surgery out of an IV bag as compared to silicone implants which come prefilled from the factory.  We typically will overfill saline implants a little to help prevent rippling which can sometimes happen easier in this type of implant than with a silicone filled on.  Does that help?

A silicone implant comes from the manufacturer filled to its volume and the plastic surgeon does not add or remove silicone. Saline implants can be filled to different volumes depending on what size it is. I hope this helps.Dr Edwards

Thank you for your question.  Silicone gel implants cannot be filled.  They come in 1 particular size for each size range.  Saline implants on the other hand can be filled with saline.  Usually saline implants are filled with 50 cc or more to overfill the implant in an attempt to avoid visible rippling of the saline implant.

Silicone implants come from the manufacturer pre-filled and sealed and cannot be altered. Saline implants, on the other hand, come with a size rating but are empty and filled after they are inserted. The final volume will be determined by the surgeon in order to get the best look for the patient. 

Silicone gel implants come in specific sizes pre-filled. Saline implants will evaporate if left exposed to the atmosphere, so they are provided and inserted empty and filled with a tube and one way valve after they are inserted. Saline implants have an optimum range of fill volumes for a given size of implants, and are typically over-filled within that desirable range to minimized wrinkling and reduce deflation risk (which seems to be higher with under-inflated saline implants). Thus a 450cc saline implant maybe be "properly" over-filled to 500cc, and this would be used when a 500cc size implant is chosen by surgeon and patient.