Training batcteria to protect ourselves

Sounds like a crazy thing but actually our body is full of bacteria that is beneficial for our life.
Can you imagine to have a genetically modified bacteria that would protect our teeth instead of destroy them?
Thinking like that is the art of Jessica Snyder. She is the author of "Good germs, bad germs" and there you can find more about the interactions and interdependence our bodies and lives have with the "micro world".