Is it true that Sientra's sizing runs differently then Mentor and Natrelle? If so, does it run bigger or smaller?

Thank you for your question.  Implant sizing is typically different with each implant manufacturer.  Here at Stillwater Plastic Surgery we take several different measurements of the patient during their consultation.  After discussing the patients desired outcome we consider those measurements and determine the best implant for that individual.  It would be my suggestion to have a consultation with a Board Certified Plastic Surgeon and discuss these questions.  Best of luck.

In my opinion, the Sientra implant runs on the larger size. I believe this to be related to the unique shape to base relationship. The 385 might make you a large D...if your tissues can accommodate it. Talk closely with your PS to be sure they understand your size goals. Grant your PS latitude to make the best, and safest, choice at  surgery with your goals in mind. Good luck and be well.

Thank you for the question. I have utilized all three of the FDA approved breast implants and have found the principles associated with breast implant selection to be the same, regardless of the breast implant manufacturer.  I do not think that there is any way to generalize whether Sientra breast implants will "run bigger or smaller". Ultimately, careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical. 
Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery ( regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. For example, I have found that the use of words such as “natural” or "C or small D cup” etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on him who makes the bra; therefore, discussing desired cup size may also be inaccurate. Again, the use of computer imaging has been very helpful during the communication process, in our practice.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery, after the use of temporary intraoperative sizers.
I hope this (and the attached link, dedicated to breast augmentation surgery concerns) helps. Best wishes for an outcome that you will be very pleased with.

Congratulations on your decision to go ahead with a breast
augmentation and for choosing a surgeon who uses Sientra as these are an
excellent breast implant which clearly has less capsule contracture (based on
all the studies).

Sizing for all of the textured breast implants first starts
with the dimensions of your chest.
Specifically we generally need the base diameter of your breast and
chest to give an idea of what breast implant size range is right for you. After that we use the profile that you like
as well as a sizing process to determine the size or profile that will work for
you in your diameter range. This may
seem more complicated than just trying on implants to get a size you like but
the results are far superior.

There is a conversion with Sientra implants that some surgeons
use but I have not found it very useful.
You are always best to go with the method of sizing that your surgeon
recommends.

I have added a video on Sientra breast implants for you.

I hope that helps.

Best regards.