Pros and cons of under vs over the muscle?

There
are two choices for breast implant placement: sub-glandular (under the breast
tissue and in front of the chest muscle – the pectoralis muscle) or
sub-muscular (under or partially under the chest muscle). The best location
depends on many factors including: tissue thickness, weight, desired outcome,
and individual anatomy. Each position has advantages and disadvantages:
Subglandular implant benefits:
A shorter
recovery time.
Less
discomfort initially.
No
distortion of the breast when the pectoralis muscle flexes.
Mild
preoperative sagging can be improved, especially if no breast lifting
procedure is performed.
Easier
surgical procedure.
Larger
implants can be placed.
 Subglandular
implant disadvantages:
The implant
may be more visible.
More
visible rippling, especially in patients with a small amount of natural
breast tissue.
Generally,
saline implants do not produce a good result in front of the muscle.
Higher
incidence of capsular contraction.
“Bottoming
out” in some patients.
Some
radiologists have more problems reading a mammogram with an implant in
front of the muscle.
 Submuscular implant benefits:
Usually
results in a better appearance for naturally small breasted women
Less
tendency for seeing ripples of the implant.
A more
natural feel to the breast especially in slender women who don’t have much
of their own breast tissue.
Less
interference with mammograms, although most radiologists take additional
views no matter where the implants are placed.
Lower rate
of capsular contraction.
Less of a
chance of “bottoming out” where the implant bulges at the lower aspect of
the breast and the nipple and areolas tend to appear excessively elevated.

Submuscular implant disadvantages:
Recovery
usually takes a little longer and is more uncomfortable initially.
There may
be an “animation deformity”, which is a temporary distortion of the
breasts when the pectoralis muscle is flexed. Body builders and weight
lifters generally prefer implants in front of the muscle.
It is
harder to achieve cleavage in women who have widely spaced breasts.
The
implants often ride higher on the chest.
Actually,
most patients who have breast augmentations today have breast implants placed
in a combination or “dual plane” position. This approach has the same benefits
and disadvantages of a total “submuscular implant”, but with a lesser tendency
to ride high on the chest wall. The disadvantage as compared to a total
“submuscular implant” is a higher tendency for bottoming out.
The
ideal placement in any particular patient depends on their particular anatomy
and understanding of the pros and cons of each approach and desired outcome..
Keep in mind, that
following the advice from a surgeon on this or any other website who proposes
to tell you what to do based on two dimensional photos without examining you,
physically feeling the tissue, assessing your desired outcome, taking a full
medical history, and discussing the pros and cons of each operative procedure
may not be in your best interest. I would suggest you find a plastic surgeon
certified by the American Board of Plastic Surgery and ideally a member of the
American Society for Aesthetic Plastic Surgery (ASAPS) that you trust and are
comfortable with. You should discuss your concerns with that surgeon in
person.  
Robert Singer, MD 
FACS
La Jolla, California
 

In most patients there's not a big difference aesthetically and implants above or below the muscle. There are certain circumstances, such as a constricted breast, or placement of the implant above the muscles preferential. At other times when there is a paucity of subcutaneous fat is sub muscular placement might be preferred. In your particular case this should be discussed with your surgeon. From the photographs I think you would be well served implants either above or below the muscle. Because there is less pain and no animation issues you might want to consider sub glandular.

Your question is a very good one, and as you have discovered, plastic surgeons are not in agreement over this issue.  While it is true that implants placed directly under the breast tissue have certain advantages, such as more readily shaping the  breast, and avoid problems such as " double bubble", and implant displacement with exercise, I believe these are outweighed by the disadvantages. Much of the blood supply to the breasts is interrupted when implants are placed on top of the muscle, which can lead to complications when other procedures such as lifts are performed. In patients with little breast tissue and body fat, the implants are more readily felt, and wripplng is a much greater problem with both silicone and saline. I placed implants on top of the muscle frequently earlier in my career, however because of these issues, I rarely do after twenty seven years.