A capsule of scar tissue forms around the implant after surgery. This is a natural reaction of the body to protect itself from the introduction of a foreign object. The formation of this scar capsule is called capsular contracture. In extreme cases, this scar capsule will result in a hardening of the breasts, which may be painful and requires additional surgery.
Textured breast implants were created to reduce the chance of capsular contracture. The textured surface of these implants allows the scar tissue to adhere to the implant, hopefully decreasing the amount of scar tissue that grows. In addition, the implant sticking to the scar capsule prevents it from moving around inside the breast. It is still debatable whether or not textured implants actually reduce the instances of capsular contracture; but evidence does indicate that textured implants have a greater tendency to rupture.
Smooth breast implants move around freely inside of the capsule. This freedom can create a more natural movement in the overall breast; however, depending on the placement of the implant, it can sometimes create an undesirable side effect known as rippling (see the Risks section). There are many variables that affect rippling, and the surgeon will guide the patient toward the implant texture for her anatomy.