Oh, no! You've got a cavity. Your teeth are the hardest things in your body, yet tiny germs are able to make holes in them. A hole in your tooth is called a cavity, and once you have one, only a dentist can come to the rescue. The key is to prevent cavities from forming in the first place. Every day, there's a battle going on in your mouth. Acids and bacteria attack your teeth and plaque builds up. Your body has superheroes--your saliva--that try to fight off acids. By brushing and flossing your teeth, you can help your body fight off the germ invaders and prevent cavities. Get a close look at the battle going on in your mouth with comic illustrations and ground-breaking photomicrographs. The photomicrographs magnify the actual cellular processes thousands of times, offering you a front-row seat for all the action.