While not common, there is a small risk of losing sensation in your nipple after breast augmentation with breast implants. The risk increases with larger implants and a subglandular placement of the implant.
I like to place the implants in a dual-plane pocket under the pectoralis muscle and I wouldn't advise using implants that are too large for your body's proportions.
The other option for breast augmentation is using your own fat to augment your breasts. This is basically liposuction of an area of your choice and injection of that fat into your breasts. There is no risk of losing sensation in your breasts with fat grafting as your nerves are not cut.