Dental caries (caries is Latin for rottenness), also known as tooth decay, cavities, or caries, is a breakdown of teeth due to activities of bacteria. The cavities may be a number of different colors from yellow to black.Symptoms may include pain and difficulty with eating.he cause of caries is bacterial break down of the hard tissues of the teeth (enamel, dentin and cementum). This occurs due to acid made from food debris or sugar on the tooth surface.