Types Of Implants
There are three types of breast implant used for mammoplasty, breast reconstruction, and breast augmentation procedures
1. Saline implant filled with sterile saline solution (saline implants).
2. Silicone implant filled with viscous silicone gel (silicone implants).
3. Alternative-composition implant with miscellaneous fillers (e.g. soy oil, polypropylene string, etc.) that are no longer manufactured (PIP implants).
More About Saline Implants
Surgical Technology Used In Saline Implants
The saline breast implant is filled with saline solution (biological-concentration salt water 0.90% w/v of NaCl, ca. 300 mOsm/L.). The early models were a relatively delicate technology that were prone to failure, usually shell breakage, leakage of the saline filler, and deflation of the prosthesis.
Contemporary models of saline breast implant are made with stronger, room-temperature vulcanized (RTV) shells made of a silicone elastomer.
The study In vitro Deflation of Pre-filled Saline Breast Implants (2006) reported that the rates of deflation (filler leakage) of the pre-filled saline breast implant made it a second choice for corrective breast surgery, after the silicone gel type of breast implant.
Nonetheless, in the 1990s, in U.S. medicine, the saline breast implant was the usual breast prosthesis applied for breast augmentation, given the unavailability of silicone implants, because of the import restrictions of the U.S. Food and Drug Administration.
Surgical Technique For Breast Surgery With Saline Implants
The saline breast implant was developed to facilitate a more conservative surgical technique, of smaller and fewer cuts to the breast, for emplacing an empty breast-implant device through a smaller surgical incision.
In surgical practice, after having emplaced the empty breast implants into the implant pockets, the plastic surgeon then fills each breast prosthesis with saline solution. Because the required insertion incisions are small, the resultant incision-scars will be smaller than the surgical scar usual to the long incision required for inserting pre-filled, silicone-gel implants.
Although the saline breast implant can yield good-to-excellent results of breast size, contour, and feel, when compared to silicone-implant results, the saline implant is more likely to cause cosmetic problems such as rippling, wrinkling, and being noticeable to the eye and to the touch.
This is especially true for women with very little breast tissue, and for post-mastectomy reconstruction patients; thus, silicone-gel implants are the superior prosthetic device for breast augmentation and for breast reconstruction.
In the case of the woman with much breast tissue, for whom submuscular emplacement is the recommended surgical technique, saline breast implants can afford an aesthetic “look” of breast size, contour, and feel, much like that afforded by the silicone implant.
More About Silicone Gel Implants
As a medical device technology, there are five (5) generations of silicone breast implant, each defined by common model-manufacturing techniques.
First Generation Silicone Implants
The Cronin–Gerow Implant, prosthesis model 1963, was a tear-drop-shaped sac (silicone rubber envelope) filled with viscous silicone-gel.
To reduce the rotation of the emplaced breast-implant upon the chest wall, it was affixed to the implant pocket with a fastener-patch of Dacron material (Polyethylene terephthalate) attached to the rear of the breast implant shell.
Second Generation Silicone Implants
In the 1970s, the first technological development, a thinner device-shell and a thinner, low-cohesion silicone-gel filler, improved the functionality and verisimilitude (size, look, and feel) of the silicone breast implant.
Yet, in clinical practice, the second-generation proved fragile, and suffered greater incidences of shell rupture, and of “silicone gel bleed” (filler leakage through an intact shell).
The consequent, increased incidence-rates of medical complications (e.g. capsular contracture) precipitated U.S. government faulty-product class action-lawsuits against the Dow Corning Corporation, and other manufacturers of prosthetic breast prostheses.
The second technological development was a polyurethane foam coating for the implant shell. It reduced the incidence of capsular contracture by causing an inflammatory reaction that impeded the formation of a capsule of fibrous collagen tissue around the breast implant.
Nevertheless, the medical use of polyurethane-coated breast implants was briefly discontinued because of the potential health risk posed by 2,4-toluenediamine (TDA), a carcinogenic by-product of the chemical breakdown of the implant’s polyurethane foam coating.
After reviewing the medical data, the U.S. Food and Drug Administration concluded that TDA-induced breast cancer was an infinitesimal health-risk to women with breast implants, and did not justify legally requiring physicians to explain the matter to their patients.
In the event, polyurethane-coated breast implants remain in plastic surgical practice in Europe and in South America; in the U.S., no breast implant manufacturer has sought the FDA’s approval for American medical sale.
The third technological development was the double lumen breast-implant, a double-cavity device composed of a silicone-implant within a saline-implant.
The two-fold, technical goal was:
(i) the cosmetic benefits of silicone-gel (the inner lumen) enclosed in saline solution (the outer lumen);
(ii) a breast-implant device the volume of which is post-operatively adjustable.
Nevertheless, the more complex design of the double-lumen breast-implant suffered a device failure rate greater than that of single-lumen breast implants.
The contemporary versions of Second generation devices, presented in 1984, are the “Becker Expandable” models of breast implant device, used primarily for breast reconstruction.
Third And Fourth Generations Of Silicone Implants
In the 1980s, the models of the third and of the fourth generations of breast-implant devices were sequential advances in manufacturing technology, e.g. elastomer-coated shells that decreased gel-bleed (filler leakage), and a thicker filler (increased-cohesion) gel.
Sociologically, the manufacturers then designed and fabricated varieties of anatomic models (natural breast) and shaped models (round, tapered) that realistically corresponded with the breast and body types presented by women patients.
The tapered models of breast implant have a uniformly textured surface, to reduce rotation. The round models of breast implant are available in smooth-surface and textured-surface types.
Fifth generation Silicone Implants
Since the mid-1990s, the Fifth generation of silicone breast implant is made of a semi-solid gel that mostly eliminates filler leakage (silicone gel bleed) and silicone migration from the breast to elsewhere in the body.
The studies Experience with Anatomical Soft Cohesive Silicone Gel Prosthesis in Cosmetic and Reconstructive Breast Implant Surgery (2004) and Cohesive Silicone Gel Breast Implants in Aesthetic and Reconstructive Breast Surgery (2005) reported low incidence rates of capsular contracture and of device-shell rupture, improved medical safety and technical efficacy greater than earlier generations of breast implant device.