In ads on TV, it all looks so simple. People use mouthwash, it instantly neutralises all the nasty bacteria hiding in their mouths, and – just like that – their dental hygiene is assured. But what's really going on when you rinse a cap-load of antibacterial chemicals around your mouth? What does that to your body, and to other kinds of microorganisms that may actually be beneficial to health? As a study showed last year, the downstream effects can be surprising, and far-reaching too, affecting much more than just your dental wellbeing. In an experiment led by scientists from the...