Capsular contracture has been greatly debated. Most of the evidence points to a low-grade bacterial infection. This low-grade infection typically does not cause problems elsewhere. Infections and other parts of your body have been capsular contracture. The best way to minimize or prevent capsule contracture is at the initial surgery by maintaining strict sterile technique and having only the surgeon touch the implant prior to placement.
Theoretically a bacterial infection or transient bacterial blood infection could possibly cause a seeding of an implant just like any foreign body. Some plastic surgeons recommend the prophylactic used of antibiotics prior to a dental cleansing.
When an implant is placed during the course of a breast augmentation the body actually forms a lining around the implant creating a barrier between the foreign object and the rest of the body. Normally this barrier is thin and soft and does not create any change in the appearance of the breast. This lining is called the capsule. If this capsule thickens, becomes harder and shrinks in size the breast will feel firmer and possibly change shape. This shrinkage of the capsule is called a capsular contracture. 92% of capsular contractures will occur within the first 12 months following surgery. Although the exact cause for a capsular contracture is not well understood there are a few things that seem to be related to this phenomena. Implants placed under the muscle have a lower incidence of capsular contracture than implants placed above the muscle. If bleeding occurs in the pocket after a breast augmentation, and is not removed the accumulated blood will gradually be broken down. As the blood is broken down inflammation occurs in the pocket which can then lead to the formation of a capsular contracture. Any type of infection in the pocket can cause inflammation leading to a capsular contracture. The infection can be very minor and not causing any other symptoms. Therefore it is unlikely that any bacteria associated with a capsule contracture will lead to an infection elsewhere in the body. Antibiotics will not effectively treat a capsular contracture.
The first answer is that no one knows for surgeon what causes capsular contraction.
Bacterial contamination is one possible contributing factor to the development of capsular contraction. However the bacteria found within the capsule are unlikely to cause infections elsewhere in the body.
Because breast implants are a foreign body there is always a chance that a severe infection elsewhere in the body the releases bacteria into the bloodstream could result in bacteria seating the implant and possibly causing a capsular contraction.