With the present generation of cohesive silicone gel implants, rupture or leakage is (virtually) impossible. Though substantial forces are generated with mammogram machines, both Allergan Natrelle and Mentor MemoryGel implants are much more durable than the amount of pressure generated by these machines. Here are the exceptions or limitations:
Older silicone gel implants CAN leak or rupture, and implant damage can occur with mammography, particularly if the patient has capsular contracture. Every mammogram technician with any experience performs mammograms on augmented breasts, and are trained in the Ecklund (displacement) technique. "Accidentally" compressing the entire breast AND implant can in some cases cause rupture of the scar capsule around a woman's implants, similar to the closed capsulotomies we plastic surgeons performed years ago for treatment of capsular contracture (no longer recommended precisely because of potential damage to older implants that COULD rupture or leak). If the breasts are soft (no capsular contracture), this is less likely of an issue, but perversely, more likely to inadvertently occur because the breasts look and feel so "natural."
I have had a patient who thought her implant was ruptured by an improperly-performed mammogram, and in fact her chest and breast turned black and blue, further frightening her. I re-operated on her 13-year post-op (previously completely soft) breast and found a perfectly intact and undamaged implant and a ruptured capsule with a small collection of blood in the pocket.
Saline implants, particularly ones with textured surfaces, can leak or rupture, and pressure from mammogram machines can be the inciting cause.
Any implant that ruptures or leaks is replaced without charge by the manufacturer, but surgery and anesthesia costs are the responsibility of the patient (or her warranty, if purchased).
Regardless of the cause for re-operation, the patient is always responsible for surgical costs, and the mammographer has usually been released from responsibility by the patient's acknowledgement that she HAS implants, and understands and accepts the risk of possible implant damage by mammography.
So, to be best prepared, purchase the extended warranty that is offered by the implant manufacturers, though rupture with the latest generation of silicone gel implants is virtually impossible. Re-operation for capsule rupture that "seems" as if the implant was damaged (like my patient) is the more likely scenario, though coverage for this may be questioned.
Second, avoid saline implants that can leak or deflate.
Third, always let the mammographer know you have implants and ensure you are having a true displacement mammogram technique that keeps the implant away from the mammogram pressure plates.
Finally, understand that your plastic surgeon is NOT responsible for replacement of your implants if anyone else (including you) somehow manages to damage them! It is more likely that your cosmetic result will be affected, and you and your surgeon should have already discussed revisional surgery and who pays for what!
Bottom line: this is a truly unlikely issue to be concerned about. Worry more about smoking, driving without a seatbelt, or taking unnecessary risks. Be well and enjoy your new look!