This is a great question. Butt augmentation in general has become very popular in the past couple of years and has become one of the fastest growing aesthetic procedures in the U.S. There are two ways to do a butt augmentation, the first is with your own fat (a Brazilian Butt Lift) and the second is with butt implants. They both can have great results and many patients have a combination of the two procedures performed.
To your question specifically about butt implants and if breast implants should be used for the butt augmentation, I personally do not do this in my practice. There are specific butt implants made for butt augmentation. The implants tend to be little firmer as they need to be able to take the abuse that our butt takes on a daily basis.
I hope this answers your question. Please consult with your board certified plastic surgeon that commonly performs this procedure.