In a word: microbiome. You may have heard about “good” bacteria and “bad” bacteria for your gut. Well, it turns out that there are also good and bad bacteria for your mouth. Different parts of the body like your skin, gut, nose and mouth harbour distinct bacterial species. This community is referred to as the microbiome and it's important to maintain these communities in a healthy state. Many products that blindly eliminate all bacteria can open the door for disease causing species.