"Tooth decay, also known as dental cavities, or dental caries, is a disease that is five times more common than asthma and seven times more common than hay fever." -- Michael C. Alfano, Dean of the New York University College of Dentistry. As warned by the World Health Organization, tooth decay is one of the world's most prevalent health problems in industrialized and especially in developing countries. An estimate of 90% people in the United States has at least one cavity. Children and senior.