What is the Maximum Size Implant That Can Be Placed Safely Behind the Muscle for Silicone Memory Gel?

I am a firm believer in Tissue Based Planning principles. There is a growing group of plastic surgeons across the world that believe a 30% reoperation or revision rate 3 years after surgery for: size change, poor position of the implants, stretching of the skin etc is way too high. If a breast implant chosen is based individually and in a customized way to fit each patient's breast, based on a few basic measurements and assessments such as breast width, stretchiness... and an implant is designed to fit in this range, the results are very consistent, full and natural and do not produce stretching or problems and can lower the revision rate to 3-5% at 3-5 years. If any implant size is chosen, eventually it will place tto much pressure on the breast and skin and thinning of the tissues, increased malposition, wrinkling and rippling etc may occur.
You are correct most patients and even some plastic surgeons do not understand that saline weighs slightly more than silicone, not less. In addition a saline implant is filled in surgery and does not include the weight of the shell of the implant...verses a a silicone implant that is prefilled and its' shell is included in the weight...so when I replace a 300cc saline implant filled to 330cc's it actually weighs 350grams/cc's so we need to replace with a 350cc implant just to get back to baseline.
Finally the most common misunderstanding in choosing an implant size is that implants come in 30-40cc increments...patients cannot really tell the difference inside the body, particularly submuscular, between a 300 and a 360cc implant although 360 sounds a lot bigger. We have to add 100-150cc before you really begin to recognize the difference.
Personally I rarely place implants, even in revision patients > 500cc...ususally this outweighs the tissues and further problems can occur. To directly answer your question, a 500cc implant is certainly larger than 350, but if you had prior saline implants your implants probably weighed 370-380cc bringing them closer to 500cc/grams. Most patients can tell between implants 100cc or greater...if your weight has changed this can also affect your breast size.
Hope this helps.

It is very important to communicate your size goals with your surgeon.  In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or “C cup” or "fake looking" means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup  size may also be inaccurate.
I use  intraoperative sizers and place the patient in the upright position to evaluate breast size. Use of these sizers also allow me to select the press implant profile (low, moderate, moderate plus, high-profile) that would most likely achieve the patient's goals. The patient's goal pictures are hanging on the wall, and allow for direct comparison.
I have found that this system is very helpful in improving the chances of achieving the patient's goals as consistently as possible.
The silicone gel implants also sits differently on the chest wall and so it may look "smaller' when compared to a saline implants - the projection will be less.
I hope this helps.

The maximum sized available silicone gel implant available is 800 cc. You can get slightly larger with a saline implant. However, you should not choose a certain size without being evaluated by a plastic surgeon to determine if it is the apprpriate size for you based on your chest and breas dimensions as well as condition of your skin envelope. You say you feel that your 500 cc implants are smaller than your 375 cc saline implants. One possible reason may be that you have different profile implants. You may have had a lower profile implant before and now have a higher profile implant in which has more projection but is narrower.