Recurring oral problems are very often caused by improper oral hygiene, and by being exposed to the same microbes and the same pathogens over and over, time and time again. This is because we eat the way we do, have oral flora that is the way it is, and encounter the same microbes from the air, from the people we kiss, from the foods we eat, as each ecosystem and climate has its own set of microbes and bacterial life that flourish on it. One of the places that microbial life flourishes is the toothbrush.