Microbial complexes detected in the second/third molar region in patients with asymptomatic third molars.

PURPOSE: Our goal was to report the detection and levels of pathogenic bacteria in subgingival plaque samples taken from the distal of all second molars in 295 patients with asymptomatic third molars. PATIENTS AND METHODS: Data assessing oral health were collected from each of these healthy patients (ASA Classes I and II). Probing depth (PD), at 6 sites per tooth, including third molars, was obtained to determine periodontal status. Subgingival plaque samples were taken from the distal of all second molars before periodontal probing. The presence and levels of 11 bacterial species were determined using whole chromosomal DNA probes and checkerboard DNA-DNA hybridization. Detected bacterial species were grouped into clusters of periodontal pathogens designated as "red" or "orange" complex microorganisms as described by Socransky et al (J Clin Periodontal 25:134, 1998) who found an association of these specific microorganisms with periodontitis. RESULTS: As a group these relatively young patients were periodontally healthy. "Orange and red" complex microorganisms were detected at levels equal to or greater than 10(5) more often if patients had a PD equal to or greater than 5 mm with periodontal attachment loss at the distal of second molars or around third molars at their entry examination. In patients with no PD equal to or greater than 5 mm in the third molar region, "orange and red" complex microorganisms were detected at levels equal to or greater than 10(5) more frequently than would be anticipated in patients with little clinical evidence of periodontal disease. CONCLUSIONS: The clinical findings of increased periodontal PDs and periodontal attachment loss coupled with colonization of periodontal pathogens support the concept that clinical and microbial changes associated with the initiation of periodontitis may present first in the third molar region in young adults.