Breast Implants are Silicone bags filled with gel or salt water. A plastic surgeon slices open the skin, usually under the breast, and inserts the implant. This procedure is sometimes used to replace breasts after cancer surgery, but most implants are done for women who want larger bosoms.
How much pain often depends on the skill of the surgeon. Of course, any type of surgery will cause some temporary soreness to the area. However, there have been a number of botched surgeries, where women have gotten infections and long-lasting nerve damage and discomfort. Also, some women who get extreme enlargements complain of muscle stress from the weight of the implants.
AOL Health