All breast implants available to women today have a silicone shell that is filled with either saline or a silicone gel, and come in a variety of volumes, projections, shapes (round or shaped) and shell surfaces (smooth or textured).

• The Filler of a Breast Implant
• The Shell of a Breast Implant
• The Surface of a Breast Implant

While both types of breast implants have a silicone shell, there are two key differences between silicone gel-filled and saline-filled breast implants: the type of material that fills the inside of the breast implant and how they are implanted during surgery.

For instance, saline-filled breast implants are filled with saline, or a salt water solution that is compatible with the human body. During breast implant surgery, the empty shell is placed inside the woman's body and then filled with saline to achieve the woman's desired, individual result. In contrast, the shells of silicone gel-filled breast implants are filled with silicone gel before being implanted inside a woman's body and the gel fill cannot be adjusted.

Women should discuss with their surgeons the implant filler material that is best for them. There are differences in the cohesiveness (firmness of the implant filler) between silicone and saline filler material. The decision of which breast implant filler is best for each woman also depends on the woman's body type and her personal goals for surgery.

Saline is a liquid filler, and thus generally less firm than silicone gel. Silicone gel is a viscous, cohesive gel material, which results in a breast implant that is soft to the touch, but can still maintain its general shape in the body.

Silicones can be engineered into a variety of forms and varying degrees of firmness, including oils, gels and elastomers. Both gel and elastomer forms of silicone are used in silicone gel-filled breast implants. The firmness of the silicone gel filler in a breast implant depends upon how the gel is "cross-linked." Cross-linking is a term used to describe how tightly the molecules within the silicone gel hold together.

The filler of saline-filled breast implants consists of sterile salt water that meets the standards of the United States Pharmacopeia (USP)1, the official organization that establishes guidelines to ensure consumers receive high-quality and safe medicines, dietary supplements and healthcare products manufactured and sold in the United States.

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The outer covering or shell of all breast implants is made of a silicone elastomer that is designed to be as durable as possible.

Today's silicone gel-filled breast implants have a thicker outer shell, a silicone patch and a silicone barrier material covering the entire surface. The silicone patch covers the opening where the silicone gel is inserted into the shell.

The thicker outer shell enables current silicone gel-filled breast implants to withstand more than 25 times the force of a normal mammogram without failure.

It is important to note that breast implants are not lifetime devices and breast implant surgery is likely not a onetime surgery. A woman may need additional unplanned surgeries on the breast(s) because of complications or unacceptable cosmetic outcomes. These additional surgeries can include implant removal with or without replacement, or they can include other surgical procedures.

Read an expert’s opinion on the strength and durability of silicone gel-filled breast implants

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In the United States, women can choose between two different types of breast implant shell surfaces: a smooth surface and a textured surface. The surgeon generally recommends the type of surface based on his or her technique and the shape of the breast implant chosen to best fit the needs of each patient.

Breast implants with a textured surface have been used worldwide for many years. According to the United States Food and Drug Administration's (FDA) Breast Implant Consumer Handbook, textured surface breast implants were designed to reduce the chance of a capsular contracture (a complication that occurs when the tissue that forms around the implant tightens or "squeezes" the implant2). Some studies with small numbers of women suggest that a textured surface breast implant reduces the chance of severe capsular contracture.3 However, other studies of a large number of women with saline-filled breast implants show no difference in the likelihood of developing capsular contracture with textured surface breast implants, when compared to smooth surfaced breast implants.4

Read the FDA's Breast Implant Consumer Handbook

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1 www.fda.gov/cdrh/breastimplants/handbook2004/devicedescription.html#1
2 www.fda.gov/cdrh/breastimplants/handbook2004/localcomplications.html
3 www.fda.gov/cdrh/breastimplants/handbook2004/surgery.html#2
4 www.fda.gov/cdrh/breastimplants/handbook2004/surgery.html#2