Probiotics are the good bacteria colonies in yogurt products with active yogurt cultures. One side benefit to eating this type of yogurt is that some components of these cultures may help kill the bad bacteria inside your mouth, which can result in fewer problems with tooth decay, gum disease and bad breath. There are potentially more than 600 types of bacteria inside your mouth, although some are beneficial because they kill or discourage even worse types of bacteria that can produce plaque (the gloppy white stuff that hardens into tartar). Some current research suggests that the probiotics in active culture yogurt products and probiotic gums may deliver good bacteria reinforcements to the front lines -- your teeth, tongue and gums -- and do it under the guise of eating a tasty (sugarless) snack.
We should note here that not all yogurt products contain active bacteria cultures, and of those, not all have demonstrated oral health advantages (some are full of sugar that can wreak havoc on your teeth). The research on this topic is ongoing, so stay tuned.