Also known as tooth decay or simply cavities which are caused by bacterial infection that cause decriminalization of the tooth. A hole is formed which penetrates the tooth through the enamel, dentin and cementum. Caries that are left untreated can cause pain and even the eventual loss of a tooth. If you can see caries or small chalky areas known as a surface caries the damage is progressed. In order to save the integrity of the tooth dentist try to spot small cavities with the use of radiography (X-rays). Dentists use a tool called a dental explorer, a sort of hooked pointy mental instrument, to diagnose caries during the examination process. That is what they are doing when they are poking about in our mouth.