When food we eat sticks to our teeth it makes a place for germs to work. The food turns bad, and the germs multiply and make holes in our teeth, which we call cavities. The surface of our teeth is made of enamel and is the hardest substance in our body. Beneath it is a layer of dentin. Inside that is the dental pulp, which contains blood vessels and nerves. When teeth start to decay and the material they are made of wears away, it affects that dental pulp and results in toothache. Cavities are cause when particles of food left in the mouth after eating begin to decay. This produces acid which eats tooth enamel. We should always brush our teeth right after eating. But if we should happen to get a cavity anyway, then we should go to the dentist right away. If we don't our teeth will become worse and worse and may have to be pulled if they're too bad.