This question has been asked since the invention of breast augmentations. The fact is, no one knows for sure. Some women have implants that last a lifetime. They never experience problems after breast augmentation surgery, and they never have them replaced. Some women had their surgeries decades ago when technology and tools were not nearly as advanced as it is today and never needed a repair. Others developed leaks, ruptures, and infections that required surgery within a few years after their initial procedure.
The vast majority of patients can expect a lifespan of 10-20 years from their implants. The FDA reports that 20% of patients have their implants replaced within 10 years of their initial surgery. The remaining 80% of patients either do not need replacements, or they have their implants replaced after 10 years.
If you are happy with the size, shape, and comfort of your breast implants, you probably do not have a problem, and you do not need to replace them.
If your breast implants are filled with saline solution, and they begin to leak, you can expect your breasts to deflate and flatten within 48 hours. At that point, you should contact your doctor and decide if you want to remove or replace the implant. If you choose to replace it, this would be a good time to make size adjustments in both breasts if you so desire.
However, if your breast implants are filled with silicone gel, they could develop a leak over time without your knowledge. A silicone implant is filled with a thick gel, and because it is usually contained in the tissue around the implant, your breasts could look and feel normal even if some of the gel has leaked outside the pouch. Silicone gel is not dangerous to the human body. It does not cause disease nor will it flow throughout the body. However, if you are concerned your silicone implant is leaking, you should consult with your doctor.
It is suggested that you schedule an MRI 3-years after your silicone implant surgery to check for problems. After that, you should have an MRI every 2-years.
Over time you may feel some pain in the breasts. They may feel hard to the touch or begin to look misshaped. This requires a trip to your surgeon. You are probably experiencing a buildup of scar tissue, and that may mean removal or replacement of the implants. Only your doctor will be able to tell for sure. Do not assume it is scar tissue, go to the doctor. If it is scar tissue, it can be corrected. If it is another medical problem with your breasts, it may require immediate attention.
No doctor can tell you that you will never need to have your implants removed. He or she can tell you that the numbers are on your side. They can tell you that most of the time you have years and years before it becomes a valid thought. Have your regular medical checkups and do not worry about any breast implant unless you find one. The chances are good that you never will.