From a health point, it's always safest to buy new nipples.. that would be my choice.. but there's the option to boil the hell out of them.. I'm sure that would kill anything that's still there??
How nice they gave you some TT bottles!!
I would reuse the bottles(sterilizing them as well) and go buy new nipples. We have registered for and gotten a few of the TT bottles, but we have a few left over from DS as well that we can use if need be. And I will do the same sterilize the bottles and then just buy new nipples.
Yay for free stuff. These TT bottles aren't cheap, so i'm really hoping they work.