Which kind of implants have the least sagging over time? Saline, silicone or cohesive (gummy bear)?

All things equal, a textured implant adherent under muscle will sag less,  If the implant attaches to the under-surface of the pectoral muscle, it will be held up by the muscle and thus not sag over time.  That said, textured implants introduce several potential problems that make smooth round implants a more attractive option for most patients.

Sagging is not caused by the actual type of implants - it’s caused by other factors including:implant placement inside the body
skin quality
implant size
breast shape before surgery

Therefore, you should consider these factors instead rather than whether they’re saline or silicone.

 Thank you for the question. There are many factors involved when it comes to if/when a patient will experience breast "sagging".  Factors such as genetics, pregnancies, weight gain/loss…may come into play.  The type of breast implant utilized during breast augmentation surgery however will NOT necessarily play a role. My best suggestion to patients seeking breast augmentation surgery: select your plastic surgeon carefully. Communicate your goals carefully as well. Working together you will come up with a good plan to achieve your desired outcome. Best wishes.