What are the pros and cons of placing silicone implants over or under the muscle?

If you have little fat and less breast tissue, then sub muscular may be better for you because it gives you a more natural appearance. The muscles serve to hide more of the implant, so it won't be so visible or palpable. Mammograms are also easier to perform. Subglandular may be an option if you are a bodybuilder and need to show off your muscles. The cons of sub muscular placement include a bit more discomfort and a bit longer of a recovery period. 

It's a great question. I strongly prefer under the muscle implants because the muscle provides another layer of camouflage for your implants. The muscle contours the top of the implant to give it a more natural slope and hide rippling of the implant. Implants under the muscle have a decreased risk of scar tissue forming around the implant (capsular contracture).  Also, breast cancer screening with mammography gives better images of breast tissue when implants are placed under the muscle. Although an implant on top of the muscle can be a good choice for some women, for very thin women there is not enough camouflage for the implant to look natural. When considering breast augmentation make sure you find a board certified plastic surgeon who will take the time to answer all of your questions and explain all of your options, so that you can decide if breast augmentation is right for you.

Well as you mention your surgeon will pick what is best for you depending on your body, the idea would be to choose which ever way you would have a more natural look and ultimately would be best for you, your Plastic Surgeon will examine you and offer you his recommendation, and explain to you why he thinks one placement or another would be beneficial for you. There is never one option that works for all women. Everyone is different and requires an individual assessment and plan.

When breast enlargement with implants first became popular, the implants were placed just behind the breast on top of the pectoral muscle.  With time, it became obvious that there was a high occurrence of hardening of the implants due to tightening of a scar tissue layer (called a capsule) that always forms around breast implants upon healing.  Despite numerous theories and lots of research, we still don't know the exact cause of this contracture (tightening) of the scar capsule, why it occurs or doesn't in some individuals, or how to completely prevent the problem.  We do know that capsule formation is a normal part of your body's healing around a foreign object.  Over the years, surgeons discovered that placement of the implants behind the pectoral muscle offers significant protection against this scar tissue tightening, so this has become the norm for most surgeons.  Also, for many patients implants placed behind the muscle look more natural because your own breast and fatty tissue camouflage the border of the implants.  So a more natural appearance and softer breasts are considered advantages of submuscular placement.  However, this is a more extensive surgery than placement just behind the breast, with more pain in the first few days post op, and some people may notice a strange "jiggling" or "rippling" of the breast when the pectoral muscle is flexed strongly.  Although this does not occur often, it can be upsetting to some patients, especially body builders.  That is why for some patients who are fitness buffs or body builders, surgeons will discuss the option of placing the implants over the muscles, as long as the patient accepts the increased risk of scar capsule tightening.

It is impossible to give an accurate assessment of what you would be a candidate for without examining you or at least seeing the photos. Generally speaking if you have very little breast tissue or some-but perky-- you might be a good candidate for placement under the muscle. Sometimes if a patient is a candidate for a lift--and the nipples do not point down)- but wants only increase in volume -- then the implants ( preferably -silicone) can be placed over the muscle.Breast implants were universally silicone and were placed over the muscle since the beginning in the 1960s. Under the muscle became popular in the 90s when only saline was used and wrinkling was prominent.Seek an experienced Board Certified Plastic Surgeon for in person consultation.