As much as I'd love a long-term solution to dental cavities, I'm leery of any treatment using silver nanoparticles, which can cross the blood brain barrier and accumulate in the brain, where they've been shown (in mice and in human models) to contribute to neurodegenerative diseases.
I'm not a biologist or chemist, so I don't know enough to judge if the method listed here is completely safe, but even a cursory google shows cause to be concerned: https://www.tandfonline.com/doi/full/10.1080/17435390.2018.1...