Is It Necessary to Replace a Silicone Nose Implant After Several Years?

I don't use silicone nose implants yet I can state conclusively that if the implant looks good and there are no problems (infection, shifting, necessitating) it never needs to be exchanged.

In short: If it ain't broke, don't fix it.  So, if you like the look and there is no signs of infection or implant rejection then I would leave it alone.  Nasal implants are constructed differently than breast implants and don't need to be replaced routinely.  

Your friends are confusing silicone breast implants with silicone nasal implants. The nasal implants are solid while the breast implants contain a gel. Epidemiologic studies from the early 1990s through 2000s showed increases in breast implant rupture rates around 10 years after implantation. This led to a recommendation to change the breast implants routinely after 10 years. The implants have changed since then so it is unclear if this recommendation still holds true. Nasal implants are solid and contain no gel so they cannot rupture. There is no need to routinely change them in the absence of any symptoms.

My response to your question/post does not represent formal medical advice or constitute a doctor patient relationship. You need to consult with i.e. personally see a board certified plastic surgeon in order to receive a formal evaluation and develop a doctor patient relationship.