Would 300cc Breast Implant Result in Natural Look?

Communication with your surgeon is critical in achieving the results you wish. I find that this is best done with the use of pictures as opposed to trying to predetermine specific implant size or profile.

The more breast surgery I do the more I realize that there is no correlation between the size or model (profile) of implant used and resulting cup size.  This may have to do with several factors including: the amount of breast volume the patient starts with, the shape of the patient's chest wall (concave or convex), the type and model of breast implant selected (saline/silicone  and low/moderate/high profile), bra  manufacturer variance  in cup sizes, the  degree  of filling of the cup  with breast tissue,  and the subjective differences in patients perceptions of cup size. 
Much of the final “look” achieved after breast augmentation surgery  depends on several factors:

1. The initial shape, size (volume of breast tissue), symmetry of the patient's breasts. In general, the better the  preoperative breast appearance the more likely the breast augmentation “look” will be optimal.

2. The experience/skill level of the surgeon is important in determining the final outcome. For example, the accurate and gentle dissection of the breast implant pockets are critical in producing  long-term  well-placed breast implants. I personally think that these 2 factors are more important than any others, including type (saline or silicone)  or model (low/moderate/high profile)  of implant.

3. The type of implant used may  determine the final outcome, especially if the patient does not have significant covering breast or adipose tissue. For example, some surgeons feel that silicone implants have a more natural look and feel than saline implants because silicone gel has a texture that is similar to breast tissue. Each patient differs in the amount of breast tissue that they have.  If a patient has enough breast tissue to cover the implant, the final result will be similar when comparing saline implants versus silicone gel implants.  If a patient has very low body fat and/or very little breast tissue, the silicone gel implants may provide a more "natural" result.
On the other hand, saline implants have some advantages over silicone implants. Silicone implant ruptures are harder to detect. When saline implants rupture, they deflate and the results are seen almost immediately. When silicone implants rupture, the breast often looks and feels the same because the silicone gel may leak into surrounding areas of the breast without a visible difference.  Patients may need an MRI to diagnose a silicone gel rupture.   Saline implants are also less expensive than the silicone gel implants.
Other differences involve how the breast implants are filled. Saline implants are filled after they’re implanted, so saline implants require a smaller incision than prefilled silicone breast implants.
On May 10, 2000, the FDA granted approval of saline-filled breast implants manufactured by Mentor Corporation and McGhan Medical. To date, all other manufacturers’ saline-filled breast implants are considered investigational.
As of 2006, the FDA has approved the use of silicone gel implants manufactured by the Mentor Corporation and Allergan (formerly McGhan) for breast augmentation surgery for patients over the age of 22.

4. The size and model of breast implant used may  make a  significant difference in the final outcome. Therefore, 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" or "top heavy" 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 breast 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.
By the way, the most common regret after this operation, is “I wish I was bigger”.

I hope this helps.

The best way to keep the look of implants natural is to keep the implants on the smaller side as compared to the volume and chest dimensions.  Choosing the right implant for you requires an exam.

Choosing the size of the breast implant is one of the hardest decisions for patients to make. To help our patients in Naples, Florida, we have obtained the Portrait 3D breast simulation system. This allows patients to simulate and visualize the appearance of implants on their own body before surgery in any direction. You can compare before and after 3D images with different sizes, styles and placement of the implant. This simulation is not completely accurate, but it helps the dialogue with the patient. Additionally, we use silicone implant sizers in a sports bra to show the patient what they may look like in clothes with implants. Using these 2 techniques we usually get the final implant within 25 cc of what the patient liked preoperatively. As for what proflie of implant to choose, this is depenendent on your breast base diameter and other breast characteristics as well as your desired volume or appearance afterwards. You state your breast base width is 11 cm. The 300 cc High Profile implant has a base diameter of 11.1 cm so it will just fit in the area. You don't want to go much beyond that, because you will then violate the natural borders of your breast and make it look unnatural. Just keep in mind that the high profile implant has more projection, thus at times can look less natural. Without seeing you in person, no one can make a real recommendation of what size implant with which you would best be suited.

It is always one of the most difficult things for women and surgeons to come to a decision about the right size implants and mutiple factors come into play, but judging from whta you describe, 399 cc implants should be fine.  Whether they look natural, etc. depends on your body and your surgeon.

It is actually very very difficult to say without examining you and taking more measurements. The measurements we are looking for are more complex than rib cage width, and take into account breast base width, thickness of tissues in the medial and lateral edges of the breast, thickness of tissues on the upper pole of the breast. In addition, we factor in the height of the nipples and the quality of the skin envelope. Finally, we try to understand what sort of "look" a patient is going for. After all that information is gathered, we look up tables and decide what range of implants might work for that particular patient. In my practice, I spend a fair amount of time having my patients try the implants out and then determine the final size range before surgery.
Furthermore, I typically have 2 to 3 consultations to decide the size of implants, incision location, and above/below the muscle. These are all decisions that take a long time to sort out. It is NOT possible to say exactly how it will look on you without ever seeing you. I can however tell you that putting in 300cc high profile implants on a thin narrow chested woman will provide a more "fake" look, and can still be very attractive. Good luck.