Nano silver could treat nasty mouth infections

Silver nanoparticles that kill yeasts that cause mouth infections will be trialled in mouthwash and dentures as a potential preventative measure against these infections.

Science Daily, 8 March 2012

TechNyou

As mentioned in the story, this is early stage research and the safety implications will be tested before the product reaches the market. I am unsure if those safety implication extend to the fate of the nanoparticles once your mouthwash is spat down the sink and enters the waterways. There is considerable research happening worldwide to determine this and although in many cases it appears the silver nanoparticle stick together and lose their potenency this will likely be environment-dependant. So there is much still to learn.  See previous TechNyou articles on this