Why is the age minimum different for augmentation for saline-filled and silicone gel-filled breast implants?

FDA approved saline-filled breast implants for augmentation in women ages 18 and older. FDA approved silicone gel-filled implants for women ages 22 and older. The age restrictions are different because the risks are different for the two products.  For example, silicone gel-filled implants will require frequent MRI monitoring to detect silent rupture (a rupture that can go undetected by you or your doctor).  There is no risk of silent rupture for saline-filled implants. In addition, the health consequences of a ruptured saline-filled breast implant are different from those of a ruptured silicone gel-filled breast implant.