The objectives of this program are to study the infectious agents resident in human dental plaque which are involved in the etiology of dental caries and periodontal disease, and to seek ways of preventing these infections. The program encompasses a spectrum of studies ranging from those aimed at providing fundamental knowledge of the ecology of odontapathic bacteria to those where the effectiveness of chemotherapeutic agents are being assessed for practical control of dental infections. The types of bacteria present in human carious lesions and those associated with the extremes of periodontal health and disease are being investigated. The odontopathic potential of prominent groups of organisms is being assessed singly and in combination with already recognized odontopathic bacteria in experimental animals. Techniques to facilitate the identification and enumeration of recognized odontopathic bacteria are being developed. Special attention is being devoted to the Gram-positive filamentous rods which are numerically prominent in human dental plaque and which include members with recognized pathogenic potential. Ecological determinants responsible for the establishment of odontopathic bacteria in the oral cavity are being investigated placing particular emphasis upon the mechanisms they use for adhering to teeth and other oral surfaces. The possible chemotherapeutic value of antibiotics and disinfectants for the control of Streptococcus mutans populations on teeth in humans is being studied. Collectively, the information obtained will be used to attempt to devise practical means of either preventing initial infection by odontopathic bacteria or ways of controlling such organisms once infection has incurred. BIBLIOGRAPHIC REFERENCES: Gibbons, R.J. 1977. Adherence of bacteria to host tissues. Microbiology. Am. Soc. Microbiol. Pub., in press. Clark, W.B., and Gibbons, R.J. 1977. Influence on salivary components and extracellular polysaccharide synthesis from sucrose on the attachment of Streptococcus mutans to hydroxyapatite surfaces. Infect. and Immun., in press.