Each style and size of butt implants has varying dimensions, and hence, different volumes. Again, the selection of the proper style and size buttock implant depends on the desired need, and "look" your surgeon feels is appropriate to achieve the best, most natural appearance.
Gluteal Implants, commonly referred to by consumers as buttock or butt implants, are primarily used for augmentation surgery (enlargement of the buttock region) and occasionally for reconstruction or treatment of asymmetry. The contents of this page will explain to you the general issues and concepts of implants and their use in buttock augmentation.
Gluteal (buttock) implants, are frequently placed beneath the fascia, or what is termed subfascially—beneath the fibrous lining that encases the buttock muscles. The fascia is commonly looked upon as an encasement for the muscle structure, offering lubrication and protection for the muscle fibers as they expand and contract. The implants may also be placed in the intra-muscular plane (within the muscle such as the gluteus maximus). The intra-muscular plane of insertion is commonly used when the patient is thin and has little body fat. Both implantation sites are well tolerated by the body.
Generally, buttock implants are available in 4 styles. The most common design is Style 3, a round, non-directional implant. These implants can be used in both accepted planes of insertion and provides uniform increased projection including upper pole fullness. Non-directional implants virtually eliminate the issue of implant rotation (movement or shifting). Directional implants such as Style 1 and 2, refers to the general shape of the implant, requiring a specific orientation and placement, as they are not dimensionally the same in all directions. Style1 and Style 2 provide an exceptional result when used in the sub-fascial plane to achieve a pre-cast desired symmetry, based on the artistic and aesthetic abilities of your surgeon in achieving the "look" they feel is best for your body style. Style 4, is a custom buttock implant with mirrored (left and right) sides. Your surgeon, before placement, can manually craft all soft-solid implants.
Over the past 4 years, gluteal implants have undergone significant improvements. Previously, implants used in other body areas were used as gluteal implants. Some implants were far too hard and were palpable (could be felt through the skin by others). Also, for example, breast implants were frequently used with unfortunate results. Breast implants, being gel or liquid filled, often ruptured and deflated at alarming rates. Most current implants are made out of "implant grade", soft-solid silicones and the hardness more closely matches the tissue they replace or augment. This provides a more stable implant and offers the natural feel one desires. Soft-solid implants, unlike breast implants, do not rupture and deflate.
Each Style and size of butt implant has varying dimensions, and hence, different volumes. Again, the selection of the proper style and size buttock implant depends on the desired need, and "look" your surgeon feels is appropriate to achieve the best, most natural appearance.
Custom buttock implants, unique to the individual, are also available and some surgeons, with vast experience in the implant procedure, use these buttock implants modifying them as necessary with surgical instruments such as a scalpel or scissors.
Sources:
http://www.buttockimplants.com/buttock-implants.html
http://www.bodyimplants.com/body-contouring-implants.html