There is an extremely small, theoretical risk of permanently losing your sense of smell, although I have not personally encountered such a case before. Indeed, understanding the anatomy and physiology of the sense of smell, it would more likely than not, improve it.
That said, you may experience temporary congestion that can last up to 2 weeks following rhinoplasty. This will impair your ability to detect smells.
May I also suggest that if preserving your sense of smell is a serious consideration, avoid using implants or any foreign material. Infection and rejection due to implant usage can impair your sense of smell.
