If you have Saline Breast implants there is no health risk of a leak. However, if you have had a leak of a Saline breast Implant you should notice a smaller breast on the side of the leak. If your breasts have remained the same size, and you do have saline breast implants, then it is unlikely that you have a leak.
If I misread your question and you in fact have Silicone gel implants, then an MRI is necessary to document the leak.
Long term studies have failed to show a correlation between Silicone Gel breast implants and systemic disease.
A serious rupture of a Silicone Gel implant can cause local problems such as granuloma formation if the gel leaves the breast area and migrates into the under arm area.
MRI is the best technique to detect a Silicone Gel implant Rupture.