Â© 2013 WebMD, LLC. All rights reserved. The teeth are the hardest substances in the human body. Besides being essential for chewing, the teeth play an important role in speech. Parts of the teeth include: â¢ Enamel: The hardest, white outer part of the tooth. Enamel is mostly made of calcium phosphate, a rock-hard mineral. â¢ Dentin: A layer underlying the enamel.
While they are often used synonymously, the terms infectious disease and communicable disease do not have the same meaning. A communicable disease is an infectious disease that is easily spread from one human to another.
contagious disease (also called a communicable disease) is an infectious disease that is capable of being transmitted from one person or species to another. Apparently they are the same. Not true. Contagious diseases are most often communicable enough to warrant quarantine, whereas communicable diseases (such as the flu) are not.