Every tooth in a man's head is more valuable than a diamond(Miguel de Cervantes) Dental caries is a microbial disease of the calcified tissues of the teeth, characterized by demineralization of inorganic portion and destruction of the organic substances of tooth. It is a complex, dynamic and continuous biological process. The dynamic balance between demineralization and remineralization determines the end result. Future microbiological studies of caries should focus on a better understanding of the physiolocal mechanisms that serve to maintain the dynamic stability in dental biofilms, thus preventing its occurrence.