This project of the Clinical Research Center for Periodontal Disease at Virginia Commonwealth University is conducted in collaboration with the Anaerobe Laboratory, Virginia Polytechnic Institute and State University. The goal of this project is to define and describe the bacteria associated with defined periodontal states. The present focus is the bacteriology of moderate periodontitis in adults and juvenile periodontitis. Depending on rate of progress, other periodontal states will also be studied. Samples are obtained clinically, dispersed and inoculated under anaerobic conditions at VCU, then transferred to the VPI & SU laboratory for definitive taxonomic study. Cultural methods are used to produce representative isolates from the floras which are characterized morphologically, biochemically, electrophoretically and serologically to the species or subspecies level. To date, approximately 220 distinct bacterial species or groups have been found, many of which are previously undescribed. Description of the most common of these will be published. Twelve species of treponemes have been isolated. Statistical analyses with respect to distinct clinical-bacteriological or bacteriological periodontal entities will proceed when sufficient samples have been analyzed.