Under the Muscle Placement for 300cc-320cc Breast Implants?

Most plastic surgeons will electively place implants under the muscle, or partially under the muscle, (dual plane approach).  This is dependent on what works in the hands of your plastic surgeon, and what your individual case may be.  It is OK to get a couple of opinions.  The opinions may be different.  That is again OK as that surgeon matches his experience to your individual issue.

In most cases I prefer a dual plane approach( under the muscle superiorly) to camouflage the upper pole.

Hi!
When we need to correct asymmetry of the breasts and some sagging, we usually do breast augmentation by placing the implants over the muscle, because it enables us to shape the breasts more precisely.  So I agree with your surgeon, although I don't know his reasoning.

The ultimate decision to place implants above or below the pectoral muscle may depend on several factors, including the type of implant(saline, traditional gel, form stable gel), the amount and quality of overlying breast tissue, pre existing shape and form of the breast and potentially several others based on your unique anatomy, desires and expectations. For the most part the decision to place below the muscles has little to do with the weight of the implant. Your surgeon should be able to explain the options to you in a way that you can participate in the decision making, and evaluate the trade offs of the various choices. If it wasn't clear go back for a second consult and perhaps get several opinions.