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Types of Implants

The silicone gel implant was first used in 1962 and since that time breast augmentation has become one of the most popular Plastic surgery procedures. Silicone was chosen as a filler (material inside the implant) because it is inert with body tissue (nonreactive, does not cause a tissue reaction). Saline (salt water) breast implants were introduced in 1965. The primary impetus for the development of saline breast implants was a smaller incision that is required for placement in the breast pocket, although there are other advantages as well. Early generation saline implants had a relatively high deflation rate in part to due to valve system (opening through which saline is added) failure and shell failure (outer covering of the implant) which accounts for their relative lack of popularity for many years. Redesign of the valve system and improvements of the breast implant shell (the outer covering of the breast implant) has lowered the deflation (leakage of saline) rate of saline breast implants. Early generation silicone breast implants had problems including gel bleed (leakage of silicone), implant shell rupture, and problematic capsule (scar) formation. The result in some patients was a breast implant related silicone granuloma, which is a benign process that results from free silicone gel leaking into the breast tissue. The breast implant related silicone granuloma is not thought to cause any connective tissues diseases (collagen vascular diseases). This has been studied extensively by many independent researchers and the conclusion was that silicone implants do not cause these types of diseases. Silicone granulomas could cause problems with the diagnosis and treatment of breast cancer.

Selecting an Implant Type

Capsular Contracture

Any smooth foreign material in the body (with a few exceptions) is covered with a “capsule”, which is a normal healing response to a foreign material. The “capsule” can be thought of as a specialized type of scar (cicatrix). This is true for many smooth inert foreign materials in the body including pacemakers, artificial (hip, elbow) joints, drug delivery devices, and of course, breast implants. In the circumstance of breast implants, the shell (and the filler in the case of silicone breast implants) of the implant is a foreign material, and is made of polymerized silicone, which is also inert (does not cause a breast tissue reaction). All breast implants are covered with this specific type of scar tissue to some degree and the capsule usually remains non-problematic (is not symptomatic). Capsular contracture describes the biologic process of excessive scar tissue shrinkage around the breast implant that can cause breast firmness and sometimes causes discomfort. Contracture in this context means a tight capsule. In some cases, the capsules can become calcified which can cause pain and can also make breast imaging (mammograms, magnetic resonance imaging, ultrasound) more difficult. The excessive scar tissue can also cause changes in breast appearance as well. The capsules surrounding a smooth breast implant is different from the capsule of a textured implant which could account for differences in problematic contracture rates between the two (less frequent with textured shells). Textured breast implant shells have been reported to have a higher incidence of wrinkling than smooth shells. The severity of breast implant capsules are based on the severity of the contracture, and assessment of severity is somewhat subjective. One classification called the Baker Breast Capsular Contracture Scale is below in a table. The etiology (cause) of problematic excessive scar is not clearly defined, but there is some evidence to support an inflammatory process (sub-clinical infection) based on a “bacterial biofilm”. Sub-clinical infection means that a small infection occurs around the breast implant or in the breast tissue but the process is not severe enough for the patient to have significant symptoms or notice it. As with many biologic processes, the etiology may be multifactorial, meaning there are many simultaneous causes, including a diathesis (tendency) to form problematic scars, (subclinical) peri-prosthetic bleeding, and non-compliance with postoperative instructions. In the case of breast capsular contracture, the specialized scar is problematic and may require further surgical treatment. In some patients the scar tissue is released and/or removed (capsulotomy, capsulectomy) to resolve the problem. The breast implants do not usually need to be removed for a period of time when capsular contracture is treated surgically. The problematic capsules are generally thought to be less frequently observed with saline breast implants when compared to silicone breast implants. This general belief may change as more data is obtained on the new fifth generation cohesive gel implants, which are relatively new compared to saline breast implants. Capsule contracture has been one of the main problems with silicone breast implants and much research and many different efforts have been made to prevent or reduce this problem, including steroids placed inside the implants, antibiotics placed inside the implant, antibiotic irrigation of the breast pocket, texturing of the implant shell, specialized coverings of the implants (polyurethane), different types of implant fillers, breast massage, special handling of the breast implants, and placement of the implants in different pockets (sub-glandular, sub-muscular, partially sub-muscular, sub-fascial, and combinations thereof).

Silicone Liquid Migration

One problem with older generation silicone implants is migration of the free liquid silicone material out of the breast pocket into the breast gland tissue. Free silicone can also migrate to other areas of the body other than the breast gland proper. This could obviously cause serious problems if the free silicone migrated to a critical anatomic area, for example, the armpit area where large nerves exist. In this case the free silicone could cause nerve compression or irritation. In addition, the migration of free silicone (silicone outside the breast implant shell) into the breast gland (tissue) proper could cause problems interpreting mammograms and other breast imaging studies (magnetic resonance imaging, ultrasound) that are used to detect breast cancer. Silicone that has migrated into the breast tissue could also cause problems in the treatment of breast cancer, including biopsies and cancer extirpation (surgical removal). The current fifth generation of breast implants are filled with cohesive silicone gel and are claimed to be superior to the previous four generations of silicone breast implant products. Many years of research on many patients will be necessary to prove the long term safety of fifth generation silicone breast implants. Those studies are currently underway.

Baker Breast Capsule Classification

Grade 1 Soft breast in which the implant and capsule are not noticeable
Grade 2 Minimally palpable implant and capsule
Grade 3 Firm breast and capsule in which the implant can be palpated and distortion might be seen
Grade 4 Firm, painful, and tender breast with significant visible breast distortion

Implants for Breast Assymmetry

Silicone breast implants are pre-filled at the time of manufacture so the exact size is determined at the time they are manufactured, and are therefore not adjustable at the time of surgery. Silicone breast implants cannot be adjusted at the time of surgery, whereas saline implants can be adjusted at the time of surgery to facilitate improvement in breast symmetry. For patients with significant asymmetry (breast do not match), a silicone implant may not be the best choice for that reason. In addition, silicone breast implants are manufactured at specific volume intervals, so if an implant is desired that is not at that exact interval volume, then the silicone breast implants would not be the best choice. Because silicone implants are pre-filled at the time of manufacture (before they are placed in the breast pocket), a much longer breast augmentation incision is required. Conversely, saline breast implants are filled after they are placed in the breast pocket and therefore require a much smaller incision. This factor alone is the reason that patients choose saline breast implants over silicone breast implants.

Breast Implant Deflation/Rupture

Rupture or deflation of saline breast implants does occur in some patients and is not thought to cause any systemic problems. Because the implants are filled with saline (salt water), the salt and water are absorbed and eliminated as would happen when one drinks a glass of water. Rupture of silicone breast implants can also occur. Rupture of silicone implants could potentially cause local problems and regional problems as well. Like saline (salt water) breast implants, fifth generation breast implants are not thought to cause any systemic problems. Many studies have been done to study the association of breast implants with collagen vascular (connective tissue) diseases (rheumatoid arthritis, systemic lupus erythematosus, scleroderma, dematomyocitis, polymyocitis) and no association has been found to date with many studies having been performed. Rupture of saline implants is not thought to cause local problems because the saline is absorbed and eliminated. Rupture of saline breast implants can easily be detected by physical exam because the breast will be smaller. Silicone implant ruptures typically cannot be detected by breast exam alone. As a result, the Food and Drug Administration has recommended that patients with silicone breast implants undergo MRI (magnetic resonance imaging) of the breasts every two years as long as the implants are present in the breasts. MRI studies are very expensive and because the implants are placed for cosmetic reasons, it is likely that insurance companies will not pay for the study. This means that the MRI of the breasts to detect rupture will likely cost much more than the original surgery over a lifetime. If a patient does have a problem with the fifth generation silicone implants and has not gotten MRI studies as recommended by the Food and Drug Administration there could be legal repercussions. There is a risk of silicone migrating to other parts of the body after rupture although it is thought to be less likely with fifth generation cohesive gel implants. The Food and Drug Administration does not currently recommend routine MRI for patients with saline breast implants.

Breast Implant Wrinkling

While some surgeons feel that implant wrinkling is more likely with saline implants, other surgeons feel that implant wrinkling is more likely with silicone implants using modern techniques. The comparison of wrinkling rates between saline breast implants and silicone breast implants is extremely difficult and suspect due to variables such as individual surgeon technique, variations in saline breast implant fill volumes (filling the implant to maximum volume, less than maximum volume, over filling volume), time after surgery of the physical exam, variation in patient response to the implants (degree of capsule formation), variation in patient anatomy, and surgeon bias. As a result, the conclusions published related to breast implant wrinkling may not be accurate.

Breast Implant Replacement

Surgical revision may be required with either type of implant, and revision is easier with saline breast implants when compared to silicone implants. Silicone implants are a relatively new product so long term studies to test safety and effectiveness are not fully known at this time.

Silicone Vs. Saline Implants

Silicone implants are much more expensive than saline breast implants and this can also be a factor when choosing an implant type. The selection of implant type is left up to the patient after the informed consent process, and the decision to choose one implant type over the other should be based on these factors and not “marketing” by the Plastic surgeon, the manufacturer, or any (financially) conflicted party. The choice of implant filler type is about what the patient wants, not about what the Plastic surgeon wants.

The primary reason for choosing a silicone implant over a saline implant is the purported more natural “feel”. Silicone implants may feel more supple than saline implants especially when the saline implants are filled to the maximum published range or higher. Some surgeons believe that silicone implants are more desirable than saline implants because they are softer and more “natural feeling”. The softness (suppleness) of natural breast tissue is in part dependent on the amount of glandular tissue present in the breast. In general, glandular tissue is more firm than fatty tissue. As a result, the more glandular tissue that is present the more firm the breast will “feel”. As aging progresses, the breast gland atrophies (and shrinks) and the breast will become softer. As a result, the breast tissue of a very young person may “feel” more firm (more glandular tissue) than the breast tissue of an older person (more fatty tissue). Equating that to the natural “feel” of the breast implants, a more firm breast implant (saline) may be a better match in softness to a younger patient’s breast and a more supple breast implant (silicone) may better match an older patient’s breast. The preference of breast implant type based on suppleness and many other factors is entirely based on opinion and preference, and every patient is entitled to their own opinion and choice.

Breast implants also have different types of shells. A polyurethane coating was used many years ago and this product is no longer available. The shells are either smooth or textured (rough). The theoretical advantage of smooth shell implants includes low bacterial adhesion and thinner “feel”. The theoretical advantage of textured implants is a lower rate of problematic breast “capsules”.

Summary comparison of Saline versus Silicone (fifth generation) breast implants

Saline breast implants Silicone breast implants
Smaller incision site Larger incision site
Adjustable size Cannot adjust size
More firm fully filled Less firm
Implant wrinkling ? Implant wrinkling ?
Less expensive More expensive
MRI not recommended MRI recommended
Product research longer Product research shorter