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.
What is a communicable disease? A communicable disease is one that is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect.