Sorry, no research specifics here, but an anecdote.  My mother has one
saline breast implant.  She breastfed two children. No problems until
they got older (3-4 months) and were gaining slowly and no one thought
to look at the fact that the implant had been, well, implanted due to
unilateral non-developing breast tissue. (She was nursing on both sides
religiously and the babies only got milk from one.  Hence, the slow
weight gain.) For this reason, when this comes up I always make sure to
ask as gently as I can about the reasons for the implants, because there
may be some other aspect that will itself impact on breastfeeding.

Andrea Simmons
LLLL, St. Louis MO