OUR KNOWLEDGE about dental caries has expanded rapidly in recent years. We now recognize several factors that were either ill-defined, unsuspected, or even ridiculed a generation ago. Dental caries unquestionably is of bacterial origin, since caries-susceptible rats maintained under germfree circumstances never develop carious lesions.1 The assault begins on the enamel surface in areas that are difficult to keep free of accumulations of food debris and bacteria. Bacterial metabolism and growth lead to destruction of tooth enamel and dentin.
Relatively little is known about the identity of the causative microorganisms. When cultures of enterococci were inoculated into otherwise gnotobiotic (germ-free) rats, typical carious lesions resulted.2 Numerous microorganisms with similar metabolic characteristics probably can cause similar destruction.
The oral flora is complex, and various influences modify or control its composition. Bacterial circumstances can vary from symbiosis, where 2 or more microorganisms reinforce each other to cause a strong