Would there be a significant visible size difference if I went from a 450cc to a 550cc Saline Moderate Plus implants?

Hello and thank you for your question. Honestly, a formal in-person evaluation would be needed to determine the best treatment. There are several reasons for this:
1) Bra sizes vary based on the clothing store (for example, Victoria's Secret tends to upsize everyone by a whole cup size)
2) Most women do not wear the proper exact fitting bra size for their bodies
3) The exact volume (in cc) needed to change cup size is different for different body types (e.g. 32A to 32D requires a different implant size than 38A to 38D)
4) Be careful NOT to fall into the trap most women do- they see a certain implant size (e.g. 285 cc) or perhaps their friend had a certain size, and they want or request this or another size based on that. Everyone's body is different- 285 cc implants on your friend might look VERY different than they would on you. Be very careful not to make this mistake, because the goal is to find the right size and shape for YOU- for your particular body and your breasts.

Because of those multiple factors, and because it is KEY to fully evaluate your breasts in person to make a full set of precise measurements to select the proper implant for you (incorporating factors like amount of breast tissue, implant type, base width, projection, etc), answering your question really would need a formal personalized consultation- to say anything before that would simply be guessing, which would be both unfair and unhelpful to you. Also, just FYI, each surgeon's measurements are slightly different, so numbers, experience, and overall aesthetic from one surgeon aren't necessarily the same as those from another surgeon!

Your breasts are such a KEY area of your body and your femininity- therefore, you should ONLY trust an experienced aesthetic plastic surgeon. As such an expert, I have had extensive training and experience with complex aesthetic surgeries under a multiple world-renowned experts in the field. I’d recommend for you to setup a formal consultation with me (or another plastic surgeon who is extremely comfortable with aesthetic plastic surgery procedures) for a formal consultation to thoroughly discuss your surgical goals, undergo a formal examination, evaluate all your options (surgical and nonsurgical), and decide on the best procedure(s) and type of anesthesia for your specific case. I hope this helps!

Dr. Donald Groves
Aesthetic Plastic Surgeon

This is always a very difficult question to answer because cup sizes vary with the bra manufacturer and plastic surgeons do not agree on the number of cc's equivalent to a cup size.  Some say from 130 - 150cc's; others, 200cc.  Trying on implant “sizers” of 450cc, 550cc, and overfill size during a preop visit while wearing a tight t-shirt, sweater, bathing suit and any other clothes you typically wear will help you and your surgeon choose the optimal implant.Kenneth Hughes, MD, ABPS Board Certified Plastic SurgeonLos Angeles, CA

Thanks for your question. There is no rule that tells how much volume makes a cup size breast difference For a woman with a slight build, it can be as little as 100 cc. For a larger woman, a cup size can equal 250 cc if not more. Your prior augmentation, you used a 420 which was filled to 450 cc. So if you use a 550 cc implant, what would be the final volume? Most people suggest that 150 cc equals one cup size for an average woman's breast, so with an implant volume that can be between 550 to 660 cc, your result could easily be a cup sized bigger. So to directly answer your question, yes you could easily look bigger. The details matter. good luck.