While comprising only two to three millimeters of the tooth, enamel is the hardest substance on the human body. That's why dentists utilize diamonds on their drill bits. Police CSI will often use dental records as a way to identify a body. A body can be burned or badly decomposed, but teeth can survive thousands of years. Tooth enamel is 97 percent inorganic.
Your teeth are really a miracle of nature. Take care of them with daily brushing and flossing!